Treadmill Tip of the Week: How to Calibrate Your Treadmill

Treadmill Calibration ToolsMy home treadmill has been host to over 50% of my total miles and the vast majority of my speedy miles over the past three years. But the feeling after a good workout is tempered by uncertainty about its accuracy, and it has damaged my confidence as a runner.

If you’ve also spent a lot of time on the treadmill this winter you also might have wondered how accurate the display on your treadmill is. Many people complain about a discrepancy in effort between running on the road compared to the ‘mill. I decided enough was enough! So before I decided on my marathon pace goal, I was going to find out exactly what the marathon goal pace I’ve been running on the treadmill actually is!

Today I will teach you how to calibrate your treadmill! And before you run away thinking it’s going to be some crazy complicated thing, I assure you it’s surprisingly easy and quick!

First, gather your materials: Soft measuring tape, light or brightly-colored duct tape, chalk, and a stopwatch. Plan to spend about 15 minutes on the process.

1. Start by placing a small strip of tape on the belt of the treadmill an inch or so from the edge. Measure from one end of the duct tape along the length of the belt, mark the spot with chalk, and note the length for Segment 1. I recommend using centimeters to make decimals easier.

2. Then turn the treadmill on slowly to move that chalk mark along and stop the belt to measure the next segment. Mark with chalk and note that length of Segment 2. Turn the treadmill on again to move that chalk mark along. Segment 3 should end with your piece of duct tape. Measure that final segment of belt and add all three measurements together to get the total belt length.

3. Next, stand on the side of the belt. Turn the treadmill on and allow it to get up to speed. Take a few seconds to practice sighting the bright tape whizzing by. Then start your stopwatch when you see it and begin to count revolutions. I found a lot of variance when I timed just 50 revolutions, so I recommend counting at least 100 to reduce error. Stop your watch as soon as you hit 100 (or 200!) and note the time.

4. Now it’s time for some math! We need to convert the number of centimeters of belt length in all those revolutions into miles, and convert those seconds into hours. Don’t get scared, just google it! Centimeters to miles. Seconds to hours.

Now what?

Are your results close to the reading on the treadmill? Yay! If not, recheck your measurements and run the experiment again. If it’s still not matching, there are a few options.

  • Check the power of the outlet you’re using and make sure no other power-sucking appliances share that circuit.
  • Some treadmills have a way to re-calibrate speed. Check your owner’s manual for details, or use this handy link.
  • As a last resort, there are businesses that specialize in maintaining treadmills and workout machines. Having a technician come out to give your treadmill a tune-up might be worth it, particularly if your ‘mill is older and you want to avoid having to buy a new one!

I found out that my treadmill spun at 8.95 miles/hour when the display said 9.0 miles/hour, less than a few seconds per mile difference. For me, that’s close enough! If yours is quite off, you can compensate by bumping the pace up or down slightly.

If you are really concerned about precision, consider repeating the calibration steps above while running on the treadmill, since the stress of your impact may change the speed. I recommend using someone else to count the revolutions. You may also want to calibrate at different speeds. Even if your ‘mill is accurate at 10 minute miles, it may not be accurate at faster paces.

It really is easy. Take a look:

Do you doubt the accuracy of the ‘mill? Going to give this a shot? If so, make sure to check in and tell us your results! 

I'm a 20-year veteran of competitive running, USATF certified coach, mom of a toddler -- and still trying to set PRs. I write about training from 5k to marathon, motherhood and competitive running, and the elite side of the sport. The 5k is my favorite race (16:56 PR) but I've got a score to settle with the marathon.

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  1. Love all these posts #ILoveTreadmills
    Can you do one on maintenance? My treadmill stopped working today (it’s my apartment complexes so I contacted maintenance) and I know it needs periodic maintenance. How do you do that?

    1. Not necessarily! I think it’s safe to assume that if 9.0 is accurate that 9.3 is also close enough but maybe not 6.0 or 7.0.

      Hills might affect this too!

  2. Great write-up! I’ve done this before, but didn’t measure the belt (just went by the belt specs) – have to remember this next time. I definitely recommend checking while someone is running (preferably you!) and at more than one speed (at least your easiest and fastest paces).

  3. I just got an old clunker treadmill off Craigs list just to get me through pregnancy and the summer with a little one before we invest in a newer good one when I start running more/training again later in the year(or maybe early next year..who knows) I can’t wait to do this with it though. Then I can start from scratch with it and really know where it’s at and go from there. I think I might do what Liz says and check it for some slow speeds (like my current walk/yog speeds) and some faster speeds..since my pace range these days is HUGE.