Treadmill pace converter

On a treadmill, the ground moves under you and you don’t have to push through air resistance or propel yourself forward as you do outdoors: at the same speed, the effort is slightly easier. Setting a 1 to 2% incline makes up for it and brings the energy cost closer to running on a flat road. It’s the most common setting to make your treadmill pace match your road pace.

Start from the speed shown on the treadmill (in mph) and its incline (in %). The equivalent flat road speed is v_equiv = v_treadmill × (1 + 4.5 × incline as a fraction), and your pace follows from 60 ÷ v_equiv. The calculator above does this automatically and also shows the speed boost that comes from the incline.

It’s a good default for easy and threshold paces, especially on treadmills without a belt that pushes you back. At slow speeds (walking, very easy jogging), the difference from the road is small and the incline isn’t essential. On the other hand, for fast intervals many runners prefer to stay flat so they don’t overload their calves and Achilles tendon.

At a 10% incline, the equivalent road speed is v_treadmill × 1.45: running 5 mph at 10% is roughly the same energy cost as 7.25 mph on flat ground. Careful, this equivalence is about oxygen cost: mechanically, climbing at 10% loads your glutes and calves more and can be rough at high speed. Incline is mostly useful for strength work or to raise the cost without speeding up.

It’s still an estimate. The 4.5 coefficient comes from the ACSM running energy equation and gives a good ballpark, but the real effect depends on the treadmill (some cushion or push the belt), on your stride and on how comfortable you are running indoors. Outdoor sensations (heat, wind, uneven ground) aren’t captured by the formula either.