Endurometry
Two different 1% stories. Jones & Doust: keep the displayed speed, add 1% to approximate still-air outdoor cost. The converter equalises ACSM VO₂ instead — 10 km/h at 1% is 5:44/km outdoors, not 6:00. A 5:00/km road easy at 1% is a 11.5 km/h belt (5:14/km).
Last updated October 5, 2026
Indoor 10 km/h is 6:00/km on the belt. Outdoors, the same number on the watch is a different session: air, camber, a belt that may be 2% fast, and a grade the console never had. Unit conversion (km/h ↔ min/km) is exact — use the pace converter. Matching effort is a metabolic model. That is the treadmill pace converter.
Two different “1%” rules
Jones & Doust (1996) reported that a 1% treadmill grade at the same displayed speed best matched outdoor energy cost in still air. Coaches still use that as a default indoor setting: 10 km/h @ 1% “feels like” 10 km/h on a calm road. Endurometry cites the paper for that convention. The calculator does not keep speed constant. It inverts ACSM’s running equation so oxygen cost matches a flat outdoor pace. At 1% you are already climbing, so the outdoor equivalent comes out faster than the belt pace. Methodology: treadmill.
Same numbers as the converter
Default inputs: 10 km/h, 1%, treadmill → outdoor. Belt pace 6:00/km (166.7 m/min). VO₂ ≈ 38.3 ml/kg/min. Flat invert: 5:44/km (9:14/mi), 16 s/km harder than the display. Opposite direction, 10 km/h outdoor at 1%: belt 9.6 km/h (6:16/km). At 0% both ways stay 6:00/km.
| Belt 10 km/h at | Outdoor equivalent (ACSM) |
|---|---|
| 0% | 6:00/km |
| 1% | 5:44/km |
| 2% | 5:30/km |
| 3% | 5:17/km |
| 5% | 4:54/km |
A 5:00/km (12.00 km/h) road easy at 1% needs belt 11.5 km/h (5:14/km) for the same ACSM cost. That is how you import an outdoor Easy from easy vs tempo vs long without pretending the belt is a road.
When to ignore the converter
If you only want Jones & Doust’s indoor default, set 1% and keep the km/h you would run outside. Do not then “correct” it again in the converter — you would double-count the grade. Use the tool when the grade is the workout (hill repeats, 3–5%) or when you want two sessions with equal ACSM VO₂. Calories at the same speed and grade: calorie calculator (same equation family).
The belt is not a certified course
Displays are often a few percent fast or slow; this page cannot see a calibration error. No wind, heat, downhill or walking model (running equation from about 8 km/h). Fan-cooled “outdoor” is still a moving floor. Treat 5:44 as metabolic matching, not a promise you would run 5:44 on the next 10K. Race prediction stays on a recent outdoor result, not on last night’s belt.
Related Tools
Treadmill Pace Calculator
Convert treadmill speed and incline to a flat outdoor pace of the same ACSM oxygen cost, or the belt setting that matches an outdoor pace.
KPH to MPH Converter (km/h to mph)
Convert kph to mph instantly: mph = km/h × 0.621371, so 100 km/h = 62.14 mph. Free km/h to miles per hour chart for road and running speeds, plus mph to km/h.
Running Pace Converter
Convert between min/km, min/mi, km/h and mph, and see the implied finish time for 5K, 10K, half marathon and marathon.
Running Calorie Calculator
Estimate calories burned running from your weight, pace, duration and grade using the ACSM metabolic equation.
Related guides
Pace vs Speed
Pace is minutes per kilometre or mile. Speed is kilometres or miles per hour. Same run, inverse units — and the converter uses the same numbers as this page.
Easy, Tempo and Long Run Paces
One comparison table for the three intensities every plan is built from: easy, tempo and the long run — with heart-rate %, VDOT % and the pace range that goes with each.
How the numbers are calculated
Treadmill and outdoor pace · Rounding and displayed precision · Sources
Frequently Asked Questions
Why isn’t 1% still 6:00/km outdoors?
Jones & Doust kept speed and added 1%. The converter equalises VO₂, so 10 km/h @ 1% is harder than 10 km/h flat — outdoor equivalent 5:44, not 6:00.
Which direction do I pick?
Belt → outdoor if you know the console. Outdoor → treadmill if you know a road pace and want a slower belt at that grade. The km/h box is always the speed you start from.
Is 1% still a good indoor default?
Yes, as a same-speed setting for still-air roads. That is not this calculation. This page is for when grade is part of the work.
Can I use walking speeds?
No. ACSM walking is a different equation. The tool rejects below about 8 km/h and above 22 km/h.
Want a new tool or fix?
Tell us which calculator, pace chart or fix would help — we build what runners ask for. Replies usually come back in 1–2 days.