How it works
Mifflin–St Jeor: BMR = 10·kg + 6.25·cm − 5·age + s (s = +5 men, −161 women); TDEE = BMR × activity factor
This page keeps the calculation centered on one relationship: Mifflin–St Jeor: BMR = 10·kg + 6.25·cm − 5·age + s (s = +5 men, −161 women); TDEE = BMR × activity factor. Inputs are normalized before the final display, which keeps mile, kilometer, pace, speed, or zone outputs from drifting because of rounding. Use the number as a consistent model output, then layer in terrain, weather, recovery, and race execution. Keep the fixed reference values in view: +5, 161, 30, 80 kg, 180, 10, 80, 6.25.
Sources
- Mifflin–St Jeor equation Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.
- Harris–Benedict, revised Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168–182.
- Activity multipliers (PAL) Total daily energy expenditure is estimated as BMR × a physical-activity level (PAL): ~1.2 sedentary to ~1.9 very active, a convention used widely in dietetics.
FAQ
When should I use the bmr calculator?
Use it when you want a fast planning number before a run, race, workout, or gear decision. It gives you a consistent estimate without asking you to create an account. Keep the fixed reference values in view: 10, 6.25, 5, 161.
What inputs matter most?
The best result comes from honest, current inputs. Recent race times, realistic body measurements, accurate workout data, and the correct unit setting matter more than perfect formatting. Keep the fixed reference values in view: 1.2, 1.9.
How should I read the result?
Treat the output as a planning reference, not a promise. Use it to compare options, set a target range, or sanity-check your watch data before making the final call. Keep the fixed reference values in view: 1990, 1984.
Does this work in miles and kilometers?
Yes. PacerRunning is written for US runners first, so miles are easy to use, but metric conversions are kept alongside them where the tool needs both views.
Why might my real-world result differ?
Terrain, wind, heat, sleep, fueling, training fatigue, and measurement error can all move the real outcome away from the estimate. The BMR bmr calculator cannot see those details.
Can beginners use it?
Yes. You do not need advanced training knowledge. Enter the numbers you know, read the result as a guide, and keep your effort comfortable when you are unsure.
BMR Calculator results are estimates from the entered data and the cited method. They are useful for planning and comparison, but they are not a diagnosis, prescription, guaranteed race result, or substitute for a coach or clinician. Keep the fixed reference values in view: 10%.