Absolutely nothing about diabetes here whatsoever! Just a reference post.
At some point it would be good to check your treadmill’s speed compared to the displayed speed. It’s not too hard to do.
Your treadmill belt makes a loop, and you need to measure the distance of 1 complete belt loop.
Get some tape and a sharpie pen and a tape measure.
Put a piece of tape down near the back end of the treadmill belt and mark it #1.
Put a second strip down close to the front edge of the treadmill belt, and mark it #2.
Measure the distance between #1 and #2 and write it down.
Turn on the treadmill at the lowest possible speed for only a second, so that #2 moves back toward the back edge, but does not go under. Stop the treadmill quickly!
Now do the same thing, adding a piece of tape marked #3 at the front edge. Measure the distance between #2 and #3. Write it down.
Keep repeating the steps until you have measured all the way back to the #1 tape.
Add up your measurements and this is one complete loop of the belt.
Measure it one more time to make sure you have it correct.
Remove all the tape and make a small mark with white-out on the belt (this will stay on better than tape when the treadmill is running).
Turn on the treadmill at a preset speed, let it get completely up-to-speed, and then use a stopwatch to time how long it takes to make 100 complete revolutions. Just watch the white spot you marked with the white-out.
Now is the fun part! The math! But I am making it simple for you.
For the treadmill belt length, use inches.
For the time of 100 revolutions, use seconds.
Divide your belt length in inches by the time in seconds for 100 revolutions, and then take that number and multiply by 5.68182
That is the actual MPH.
Example, supposed you set your treadmill for 6.0 MPH. If your treadmill belt is 143.5 inches, and it takes 132.8 seconds for 100 revolutions, your actual treadmill speed would be 6.14 MPH.
(143.5 / 132.8) x 5.68182 = 6.14 MPH