Turn a treadmill speed into running pace — and see what the incline is really worth.
| km/h | mph | Pace /km | Pace /mi | Flat-equivalent /km |
|---|
Treadmills display speed (km/h or mph), but runners think in pace (minutes per km or mile). The conversion is a simple reciprocal: pace per km = 3600 ÷ speed in km/h. So 12.0 km/h is 5:00/km, and 6.0 mph is 10:00 per mile. The cards above convert your exact belt speed; the chart shows the full range so you can plan interval settings before stepping on.
Incline changes the effort, not the belt speed. This converter uses the ACSM running-economy equation to compute the flat-ground equivalent: the outdoor pace that costs the same oxygen as your belt speed at your incline. At 1% incline the equivalent is about 4.5% faster than the belt pace — which is why the common advice is to set 1% to mimic outdoor running: it compensates for the missing air resistance and the belt assisting your leg turnover.
The 1% convention comes from a 1996 study showing it best matches the energy cost of outdoor running at paces faster than about 5:00/km. At easy paces the difference is negligible, so 0–1% is fine. Use higher inclines as deliberate hill training, not as a default.
60 ÷ 7.0 ≈ 8:34 per mile (about 5:20 per km). The chart above covers the full range of common belt speeds.
Easier: no wind resistance, perfectly even surface, and the belt helps leg turnover. Harder: heat builds up indoors, and the fixed pace removes natural micro-variations. On balance most runners find a given pace slightly easier on the treadmill — the 1% incline roughly evens it out.
It's based on the ACSM metabolic equation, a population average. Individual running economy varies, so treat it as a good estimate (within a few percent) rather than an exact match.
Belt speed is usually calibrated within a few percent, but worn belts and user weight can affect it. If your treadmill and GPS watch disagree, the truth is typically in between — trust effort and heart rate over either display.