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calibrate nike+ipod sport kit

If you’ve read my early accounts of running with the Nike+iPod Sport Kit, you’ll know I was extremely pleased with the accuracy of the sensor right out of the box, especially because I was using it with a pair of Saucony Hurricane shoes and not the special Nikes. Since then, I’ve heard from several people who have tried the Sport Kit but aren’t quite as happy with its accuracy, with some reporting it being off by up to 10%. Thankfully, Apple anticipated this problem and has provided a simple fix: Calibration. With proper calibration, the Sport Kit can be just as accurate with your “hacked” shoes as it is with the special Nike+ shoes.

Personally, I think a 10% variation isn’t too bad for a $30 accessory right out of the box, but it can obviously have a huge impact on your workouts, especially if you run long distances. I wouldn’t be too thrilled if the iPod voice was congratulating me for finishing my first marathon if I still had 2.6 miles to run! Since most of the feedback I get is from people who are using their own shoes with some version of my “shoe hack,” I did a little reading on the web and found that even people who are using the Nike+ shoes are experiencing less-than-perfect accuracy out of the box. My (non-scientific) conclusion is that the accuracy of the default calibration has less to do with shoes, and more to do with an individual runner’s stride, running style, foot size, etc. In other words, don’t try to solve an accuracy problem by running out to buy the Nike+ shoes, you may get the same results. Try calibrating first.

Calibrating the Sport Kit is easily done with just a little bit of planning:

1) Find a running track or route where the exact distance has been measured.
This is probably the trickiest step of the process. My usual running route is roughly three miles, which I’ve measured by my car’s odometer to confirm. But because there are several curves and turns, and I typically don’t run down the center of the street, my measurement could be a tenth of a mile off or more. This has never really mattered to me since I just run for fitness, but for calibrating my sensor, it probably wouldn’t do. The best bet for finding an accurately measured distance would be to go to your nearest high-school or college athletic field running track. The standard distance around the inside lane is 400 meters, which is the default distance on the iPod for calibration. If there’s no track accessible to you, check with a local running club to see if they have map of pre-measured routes in your area. If you need to measure a route via your car or bicycle odometer, try to find one that’s a straight line from start to finish. Curves and turns will increase the variation between your car’s path and your running path. Lastly, the Nike+iPod User Guide notes that the accuracy of the kit may vary depending on running surface or incline. So if you generally run on a grassy, hilly route, you should calibrate your sensor under similar conditions… not on a hard, level track.

2) On your iPod, select Nike+iPod > Settings > Sensor > Calibrate.
I found this to be the second trickiest part of the process, only because I expected the Calibrate option to be listed directly on the Settings menu, not one menu deeper. Having switched to Apple computers nearly four ago, I’ve become spoiled in my expectation that everything will work completely intuitively. When an option doesn’t appear on the menu that I expect, it causes me temporary dizziness and disorientation (ok, not really, but it is surprising).

3) When you select Calibrate, this screen appears:

Calibration improves the accuracy of workouts.

By running or walking a known distance at a natural pace you can help Nike+iPod adapt to your workout style and provide the most accurate data.

The next menu offers two choices: Walk and Run.

Choose Walk to calibrate your walking pace.

Choose Run to calibrate your running pace.

Press the center button to continue.

Don’t be shy… press the center button.

4) Select Walk or Run.
The User Guide that comes with the Sport Kit recommends that you calibrate for both, running first, then walking. If you do a combination of running and walking, this is definitely a good idea. If you’re just a runner, it probably doesn’t hurt to calibrate for walking pace as well, but if you’re a walker, there’s probably no need to kill yourself trying to run 400 meters just to calibrate for your running pace.

5) Choose a distance.
The first menu selection is the default distance of 400 meters. This is the standard distance of the inside lane of a running track. The second selection is Custom. Here you can input the number of miles or kilometers of your course starting from .25 miles (.40 km) up to 1.25 miles (2.01 km). I had read somewhere that if you’re a long-distance runner, you should select a longer course for calibration, but I’m guessing that the iPod gets all the info it needs in the first 400 meters.

6) Select your playlist.
After selecting your music, the voice will tell you to press the center button to begin your workout.

7) Press the center button and start running.
Don’t think about the fact that your calibrating your Nike+iPod Kit, just run naturally and comfortably. When you’ve finished the distance, the voice will tell you to press the center button to end your workout. Do it.

8) Press the menu button to finish calibration.
Once you’ve stopped running, press the menu button. At this point, you’ll be told whether the calibration was successful. You can now save the calibration setting, or choose not to and try again.

9) Check the result.
After you’ve saved your calibration settings, try running double the distance and check to see if you get an accurate result. If you’ve just calibrated to 400 meters, try an 800 meter workout. It shouldn’t be off by more than a couple hundredths of a mile (or km).

Lastly, I’d suggest that whether you’re using a “shoe hack” or not, go back and check your calibration every few weeks, especially if you’re training for specific distance or speed goals. The Nike+iPod user Guide mentions that results can vary based on temperature. If you calibrated your kit when it was 90 degrees outside and now it’s 60, it may be a good idea to do it again.

The Nike+iPod Sport Kit will never be perfectly accurate under every condition, but by following these simple calibration tips you’re likely to have the most accurate results possible… whether you’re using the Nike+ shoes or not.

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36 Responses to “Want Better Accuracy From Your Nike + iPod Sport Kit? Calibrate”

  1. Tony Gee says:

    After reading your story on how the sensor works, it dawned on me that the micro piezo sensor is allowed to “flop around” it considers that a step and counts it as such. This might be the reason why inclines will throw the calibration off, as you tend to shorten your stride on uphills and actually lengthen it slightly on downhills. this compensation should negate itself if you run an out an back, but on a point to point or loop this may throw off the accuracy even more. My first hack had me create a little “bag” that the sensor was placed in and I attached it to my shoe laces. The bag was flopping around, so it would register anywhere from 1 1/2 to 2 “steps” per my actual footfall. This threw off my accuracy by about a 1/2 mile on one of my 4 mile courses. Once I attached it underneath the laces (still using safety pins to hold it in place) the accuracy was down to about 1/10th of a mile (which is kind of accaeptable). I do intend on going to the local track and actually calibrating it. I will probably calibrate it to a mile though, to compensate for stride length based on just normal running form. The temp factor is interesting as the piezo is metal and therefore would either expand or contract based upon outside temp. But I must agree that the fact that this little $30 sensor is within 1/10th of a mile accurate is still a bargain. Most of my courses are measured using one of the mapping services that utilize the gMap (I use http://www.runstoppable.com) so I use that for accuracy (and even that is can be off by the same %)so I use the kit as another tool to help me in training and get my pace on the fly or when I decide to deviate on trails or where the maps can not calculate the distance. For me its a great tool.

  2. There are a few points to your piece I’d like to comment on. I have calibrated my iPod Sport Kit over a dozen times to check different methods and results. It will never be as accurate as GPS, but it is very, very good.
    1. You say, “I’m guessing that the iPod gets all the info it needs in the first 400 meters.” True, but the further you run the better the average stride the Sport Kit will get to use for future runs. If I use longer strides than normal for 400m (a short run for me) then on a longer run, if I eventually shorten my stride, the Kit will think I’m still moving 10 feet per step (calibrated value) when I’m only moving 8 feet per step (actual value). The stride is of course exaggerated to make my point. Our first attempt at calibrating was worse than the factory calibration. Therefore, a longer calibration will get more of my average stride than a short calibration. A NOTE: if you never run over 1.25 miles, calibrate using a shorter distance. Otherwise, you may get tired and your stride may get chopped toward the end or the distance, which will skew your calibration. The Sport Kit is nothing more than a pedometer, better than most, better technology, but still a pedometer.

    2. The temperature they speak of in the manual has no effect on the device. It’s talking about temperature effect on a persons stride. From the manual “Even after calibrating, the accuracy of the distance measurements may vary depending on gait, running surface, incline, or temperature.” An incline will shorten your stride. A long decline can increase your stride. Running on the beach will shorten your stride. Point is, a hot day can shorten your stride. The only time you really need to recalibrate is when your stride changes – for example, if you’re training to physically lengthen your stride. **Another recommendation, if you run exclusively on trails – calibrate on a trail. Your pavement or track stride is much longer than your trail or sand stride.

    3. It is important that when using a “shoe hack” the sensor stays stable and oriented along its long axis. As the device slides sideways or at an angle the results will vary wildly. The more consistent the orientation of the sensor, the better the results of the Sport Kit.

    4.We calibrate with the iPod set at 1.25 miles on a 1.26-mile route mapped out with a GPS receiver. This ensures that we (almost always*) run at least the desired/set distance. We have, after calibrating, ran with a GPS at least a dozen times. The Sport Kit is now rarely off more than .01 miles per mile. Because we ran slightly (very slightly) further than the set calibration distance, the error is always on the short side. Now, if we dial in a 5-mile run, we may run an extra 1/20 of a mile total. This is much better than before calibration where the Sport Kit may say we reached 5 miles and physically we have not even reached the 4.5-mile marker. With our results, on a marathon (26 miles) we should be off no more than a 1/4-mile. And because we calibrated the Sport Kit to be a few steps short of the actual distance, we will not hear that we are finished before we hit the finish line. *strides change based on conditions.

    Finally, we would always run about half a mile before we calibrated. This wears us down slightly and stretches our muscles thereby giving us a more accurate average stride. Again, if you usually run 3-5 miles and calibrate your Sport Kit with a 400-meter run after just getting out of your car, your stride is probably different than the average stride of your longer run.

  3. Podophile says:

    Thanks Tony & Palmer… Good stuff!

  4. Tony Gee says:

    Palmer great comment. I suspected that going longer would be better for calibration. Nice tip on on “warming up ” then calibrating will do.

  5. Sally says:

    How often have you guys had to calibrate? I still do not trust mine. (got it for fun) I compare it against the garmin. Do you think calibrating before an important event is good or should I just leave it alone?

  6. salle says:

    Help! I just walked 1/2 mile to calibrate my sensor and it registered .07!!
    What’s wrong and what can I do? I have the sensor in the tongue of my shoe.
    Thanks for any help! Can’t wait to use this as I do half marathons and this
    is great for training (if I can get it to work)

  7. Jason says:

    I have had pretty poor results with calibration. Out of the box, the kit underestimates by
    about 20%…not abysmal for $30, but not necessarily desireable either. Thus far, my calibration
    attempts have made the results worse. I’m fairly certain it has to do with average stride length
    changing throughout longer workouts. My long runs are 8-10 miles right now, the longest calibration
    run available on the sensor is 1.25 mi. It would be nice if you could calibrate with a 5K or 10K run.
    Being off 20% of a 10K isn’t so bad, but 20% of a marathon is way too inaccurate to be useful.

  8. redbirdie says:

    Just a comment on step 7 (… When you’ve finished the distance, the voice will tell you to press the center button to end your workout. Do it…) You should be relying on the actual distance marker on the ground, and press the MENU button when you reach that, regardless whether the voice tells you you’ve ran your distance. Then accept the calibration, as in step 8. After all, you’re telling the iPod what the correct distance is, not the other way around. I reached my half mile calibration marker when the Nano still said .48 mi under the default calibration, so hopefully the calibration will be more accurate now.

  9. Tate says:

    But what happens when you repeatedly get a calibration error? I go to the track, run the 400 meters (one lap, right?), and the iPod pretty much consistently thinks I’ve gone 800!! It prompts me to try again…

    Would it be more accurate to try on a straightaway?

  10. Gabriel says:

    I just tried to calibrate mine because it’s way off. I have measured a distance of 1.7 km and jogged it today at my normal pace, the iPod told me 440 meters. What should I do? I was really dissappointed with the calibration because I thought it would allow me to tell the iPod that “this distance I just ran is 1.7 km and use this from now on”. Instead it told me the distance I just ran didn’t match the selected one. Well of course not. If it did, I wouldn’t have had to calibrate it, not would I. Anyone have any ideas. I’m not using the iPod shoes just the iPod strapthingy to attach it to my shoe.

  11. Miguel says:

    Gabriel,

    I also had a similar problem with calibration. Ensure that the white part of the sensor is facing down just like it would if you had placed it in the Nike shoe.

    So far that has worked for me although I tend to still get a 10% variance which after reading this blog may be due to my training on the treadmill.

    Cheers.

  12. [...] First, you should calibrate your sensor to match your gait. It has both a walking and running calibration. All I did was get on a treadmill and walk/run .25 miles to calibrate mine. Easy peasy. Mine was actually spot-on right from the start, but I’ll check it again in a few weeks and see if it stays consistent. (So yes, you can use it to track your walking – FAQ.) [...]

  13. Gabriel says:

    Thank you Miguel. Yes I’m an idiot and I had the sensor upside down. Works perfectly now.

  14. jack says:

    Nice site actually. Gone to my favourites. Thanks for creation.

  15. joesuburbs says:

    obviously, having a cheapo sensor in your shoe that inaccurately measures your stride is not the correct method for determining distance/time/etc. A device that might be more expensive, but one that measures distance/time/etc. on the basis of GPS would be far more accurate.

    Oddly, though, inaccuracies notwithstanding, the popularity of the Nike+ website is amazing.

    People have inaccurately logged multiple millions of miles.

  16. Podophile says:

    joesuburbs – After 6+ months of use, my Nike+iPod kit is still consistently accurate within one percent or so of my actual distance. That’s pretty amazing for a “cheapo sensor.” I’m really not sure how a GPS system would improve my running experience.

  17. Amanda Pescud says:

    This website was more than extremely useful
    I had several questions about my nike + ipod nano, having been using it since October 2006. I also had many questions about buying same for friend who has an ipod mini etc… All were answered, more info too, in a language I could understand and with humour
    Thank you

  18. [...] Another thing worth a mention is the accuracy, I’ve read a number of reviews criticising the Nike+ kit for it’s inaccuracy. I have no doubt that they were being honest but just so you don’t only hear bad things regarding accuracy, mine was very accurate right out of the box, I still haven’t calibrated it because there is no urgent need to. If you use the Nike+ and find it inaccurate, calibrate, multiple times at different paces and distances if needed and if that doesn’t work get it replaced under warranty.Read more on accuracy at Podophile. [...]

  19. Deb says:

    Even after calibration mine is pretty inaccurate and I’m not sure why. I’ve got the sensor correctly placed in my Nike shoes – so that’s not the problem. I’ve calibrated on a track and then tested it on the same track. My times for both the calibration laps and test laps are within 2 seconds. I’d guess that means my number of strides and stride length are almost exactly the same – this is reasonable because I have years of practice running. Still the thing is way off – running at an 8min/mile pace it can say I’m running at 8:46/mile; that’s so far off that its useless. The other strange thing I noticed is that the big read numbers on the nano display that are counting the mins&secs don’t count evenly – I tried jogging at one stride/sec – every few steps the display would force me to “double step” to keep up with its count. And every so often (once a min, maybe) the display actually skips a second; that is it will go from 17 to 19. Anyone else had these problems?

  20. snappiness says:

    Argh! At first this thing was telling my my pace was either “zero” or “25 minutes” or an equally slow pace. So I found this web site, taped the sensor on my shoe correctly, and went running. Suddenly I’m running at a 7:00 pace, which is much faster than my distance pace. So today I went to a track to recalibrate. Three times I put in 400 meters and did my lap, but the pod says I ran more than that and has me at a 6:30 pace!!! This is maddening. When I ended the calibration there was no option to “accept” the calibration, so I’m not sure what that is. The iPod does say it was recalibrated in 1/9 so supposedly it worked. Except it didn’t.

  21. Podophile says:

    Snappi – Don’t know what to tell you. Is your sensor under your laces? Are you sure it’s not moving around (even slightly)? If you’re confident that the sensor is attached correctly, you may have a defective sensor. Try taking it into an Apple Store. Apple has been good about exchanging bad units.

  22. Zaal says:

    Hi guys. Great advice on this.

    Just a question – how badly does your sensors react to changes in pace – i was doing a 5km today on the track and it was relatively accurate until I picked up the pace considerably on my last 400 meters. It noted that I had 400m left and so I started a sprint, and after I actually finished the lap, it still said 200 meters to go…what could be causing this…how good are your devices in responding to sudden changes in pace?

    Cheers

  23. J says:

    Zaal: I have the same experience with sprinting and have poor accuracy in general, probably because I am a fast runner with a pretty long stride. For my first run with the sensor uncalibrated it actually measured only HALF the distance i ran.

    Anyway, great tips on calibrating here, I’ll try to sort it out!!

  24. joel says:

    I’m having the same problem as others here. When I tell the unit that I’ve just finished .50 miles, it tells me that the calibration did not match the distance entered. I thought I was telling it where the .50 miles was??? I’ve tried this over and over and get the same reading from the unit at 0.04 miles.

    Any thoughts?

  25. snappiness says:

    It turns out my unit had a dying battery. I calibrated and tested it extensively, then Apple asked for it back and sent me a new one. I calibrated it yesterday and it’s working great duct-taped to my laces. Thanks for the help!

  26. Chris says:

    I’ve run twice with my Nike+iPod. The second time was to calibrate it because it was so off when I ran on a trail the first time. (I’ve taken many tips from this blog – thanks!)

    Calibration aside, the thing I can’t understand is that the distance displayed on the iPod is much greater than what the woman tells me when I press the middle button and at the end of the workout. What she says is somewhat accurate, but the display is way off.

    Has anyone else ever noticed a discrepancy like this? Any suggestions or is this an indication that it’s a malfunctioning device that needs returned?

  27. Nick says:

    Ok Im a bit confused with calibration. I walked .25 on a track today…with my sensor, secured tightly to my laces. While i was coming up on the end of the lap I was watching my nano to see when it would register .25 miles. It actually registered it about 10 steps past where i originally started. I waited till the senser registered .25 miles to stop my calibration. I repeated the same process only with running. It actually hit .25 miles almost exactly where I started and that is where i stopped the calibration. Did I do this correctly or should I have done something different? I normally run b/w 2-6 miles but am training for 9 miles. Is there anything i should be doing different for calibration?

  28. Cat says:

    Firstly – great site, have now tried all the tips mentioned above, but still can’t get my Nike + to read properly.

    Have now calibrated and re-calibrated multiple times. Have even tried doing a long warm-up before calibration to make sure I was into my normal stride pattern, but the sensor is still overestimating distance considerably. Did a 7.6 mile run yesterday, but the sensor was telling me I had run 8.8 miles! A huge discrepancy. It’s a little more accurate on shorter distances (a 3.5 mile run became a 4 mile one according to the device) but still way over the expected percentage variation.

    I don’t wear Nike shoes, and have bought one of the little velcro pouches to hold it. It is laced tightly as far down my laces as I can get it, and as far as I can tell, it doesn’t wobble or shift as I run.

    I am at the end of my tether! Was hoping to use it during the marathon next month, but can’t imagine anything more depressing than the sensor telling me I’ve finished when I’ve still got miles left to run :-(

    Any suggestions?

  29. Andrew Smith says:

    Timing issue — I have successfully calibrated my nike ipod, I love it, the distances seem to match up fine. But, the time runs slow! I mean, more than 1 sec/min, so after a 5K it shows more than 25 seconds less time! This happens consistently every run. I can compare it to my watch and see that the ipod is running slow.

    Anyone seen this, or have an ideas about this? I wouldn’t think that it is related to calibration, since that calibrates distance, not time. I’d love to get this fixed, it affects my minutes/mile and overall workout times.

  30. Tom says:

    Calibration,

    I calibrate at 400M distance, upon completion of 400M (based on running a pre-measured distance), I hit the menu button to end the calibration, however the Nike + says I have not run far enough. My Nike + is not measuring correct distance, so how would it know I was not running far enough? I can’t seem to get around this and consequently my distances are under reported by up to 50%

  31. Mike says:

    1) Make sure the sensor is placed correctly in a Nike+ shoe (don’t be a tight ass, Nike+ shoes are great)

    2) Try and run/walk at your average pace.

    3) When you have ran the set distance say for example a 400 metre track, stop calibrating at the end of the 400 metres regardless of whether your iPod says you have ran 2 metres of 2000 metres.

    4) The Nike+ will never be 100% accurate but it is bloody close!

    5) If all else fails you might have dodgy equipment therefore it needs replacing.

  32. Oskar says:

    While calibrating, I found that when i ran 400m on a track, the default distance told me I’d only done 340m. When I press menu, it says it has failed because I have not completed 400m, when actually I have. Should I sprint the 400m metres to get better times?

    I measured another track on Google Earth, and it turned out to be 920m. When I ran it under three different calibrations, it came out at about 720m. I have quite a large stride.

    Any ideas?

  33. karonty says:

    go to the track and calibrate with 400 m. then measure the rest of your mile and look at the distance every time you cross the starting point. This worked out for me and my next mile reading was off by 1/10. If you know your pace per mile stick with it and your distance should be fairly accurate when you run on flatter surfaces. My biggest problems is nike + does not do well on hills, and I run many hills….. the shorter stride makes for a huge discrepancy and i use gmaps pedometer to help out.

  34. al says:

    I have an ipod touch, nike shoes, and the sensor installed correctly.
    I calibrated for walking and running on a 1/2 mile track.
    I checked the calibration at that time for running and it is accurate to 1/100 of a mile.
    Today I walked 2 miles and it was off 1/4 of a mile.
    Does the software know if you are walking or running? When you start a run or a walk the software does not ask if you are walking or running. Why is this device very accurate when I run and not when I walk?

  35. Podophile says:

    The Nike+ system was designed for runners. The sensor in your shoe measures, among other things, how hard your foot is hitting the ground, and the software uses that measurement in its calculations. It does work for walking, but as you’ve discovered it can be less accurate.