1 percent. Jones and Doust (Journal of Sports Sciences, 1996) measured the oxygen cost of treadmill and outdoor running and found a 1 percent grade most accurately reflects flat outdoor running at speeds between 2.92 and 5.0 meters per second, roughly 10.5 to 18 km/h. The calculator applies the same logic through the ACSM running equation, so a belt at 1 percent converts almost exactly to your flat outdoor pace.
Most consoles label speed in mph, so 7.0 means 7 mph: about 8:34 per mile, 5:20 per km, or 11.3 km/h. If your console reads km/h instead, 7.0 is a brisk walk, not a run. The calculator accepts both units, so set the toggle to match your machine.
10.0 km/h, which is 6.2 mph. A 5K is 5 kilometers, so covering it in 30 minutes takes exactly 10 km/h on a flat belt, a 6:00 per km or 9:39 per mile pace. Add the standard 1 percent incline and the effort matches a 30-minute 5K outdoors.
For energy cost, yes, within the tested range: the Jones and Doust study validated the rule between 2.92 and 5.0 meters per second. At easy jogging speeds air resistance is small, so a level belt is already close. A 2024 validation study in Current Issues in Sport Science found incline conversion charts reliable only up to about 4 percent, so this calculator marks results above that as an extrapolation.
Percent grade on nearly every console: rise over run, not degrees. A 15 on the display means a 15 percent grade, which is only about 8.5 degrees of actual slope. This calculator uses percent, matching your machine.
The 12-3-30 routine (12 percent incline, 3 mph, 30 minutes) is a walking workout, and 3 mph sits below the roughly 5 mph floor where the ACSM running equation applies, so a running calculator cannot convert it honestly. The steep grade is still real work: the same 12 percent climb at running speeds converts to a dramatically faster flat pace, which you can test here at 5 mph and above.