Quick answer: walking at 3.5 mph on a 10% incline for 30 minutes burns about 318 kcal for a 160 lb (72.6 kg) person (280 kcal net of resting). Running at 6 mph on a 1% incline for 30 minutes burns about 396 kcal for the same person.
How the tool picks an equation
Treadmill speed alone does not tell anyone whether you are walking or jogging, and the two gaits cost very different amounts of oxygen. So the calculator offers both ACSM equations. On Auto it uses the walking one below 5 mph and the running one at 5 mph and above, because the ACSM table states the running equation is most accurate above 5 mph (134 m/min) and the walking one from 1.9 to 3.7 mph. If you jog slowly, set the select to Running. The tile labelled "if running instead" (or walking) shows the alternative so you can see how much the choice matters: at 4.5 mph on the flat for 30 minutes, the walking equation gives 166 kcal for our 160 lb example and the running equation 295 kcal.
Example you can check
3.5 mph is 93.9 metres per minute. On a 10% incline the walking equation gives 0.1 x 93.9 + 1.8 x 93.9 x 0.10 + 3.5 = 29.8 ml of oxygen per kg per minute. For 72.6 kg: 2.16 litres a minute, times 4.9 kcal per litre = 10.6 kcal a minute, so about 318 kcal in half an hour. The popular 12% incline, 3 mph, 30 minute routine works out at about 309 kcal for the same person.
Incline is where the calories are
For walkers, the grade term (1.8 x speed x grade) grows fast: at 10% it adds almost twice the oxygen of the flat walking term. For runners the grade term is smaller relative to speed (0.9 against 0.2), so a raised belt matters less in proportion. That is why steep incline walking can approach the hourly burn of an easy run.
Caveats
- Holding the handrails takes weight off your legs, so the real burn is lower than the equation assumes.
- The console estimate on the machine uses its own formula and often a default body weight, so expect a gap between it and this page.
- Belt speed can drift from the display on worn machines.
- Results are averages for adults, not measurements, and not a prediction of weight loss.
Convert belt speed to pace on the treadmill pace chart. For an outdoor walk or run, use the walking calorie calculator or the running calorie calculator.
Sources: ACSM's Guidelines for Exercise Testing and Prescription, Table 7.3 metabolic calculations (as reproduced by Texas Tech University); ACSM's Guidelines for Exercise Testing and Prescription (Wolters Kluwer). Rules checked . Found a problem? Tell us.
Questions
How many calories does 30 minutes on a treadmill burn?
It depends on speed, incline and weight. For a 160 lb person: about 318 kcal walking 3.5 mph at 10% incline, and about 396 kcal running 6 mph at 1% incline.
Are treadmill calorie counters accurate?
They are estimates like this one. Some ask for no weight or use a default, and none can see whether you hold the rails. Use one method consistently to compare sessions.
Does holding the handrails reduce calories burned?
Yes. Leaning on the rails supports part of your body weight, so you lift and carry less, and the equation (which assumes no support) overestimates.
How many calories does the 12-3-30 treadmill workout burn?
For a 160 lb person, 30 minutes at 3 mph and 12% incline comes to about 309 kcal by the ACSM walking equation. Enter your weight above for your own figure.