BMR Calculator
Basal metabolic rate (Mifflin-St Jeor).
How to use BMR Calculator
Estimate your basal metabolic rate with the Mifflin-St Jeor equation.
Open BMR Calculator on toolpermarket and enter your values in the fields below.
In the Age, weight, height field, enter your stats in the requested units. Use kilograms and centimeters for the Mifflin formula.
In the Sex field, pick the biological option the formula expects. It adjusts the constant because body composition differs.
Press Calculate to compute the result. The output appears immediately below the form. You can change any input and run it again to compare results.
Read the result and use it as needed. If the number looks off, re-check your inputs and run it again — the math is deterministic, so the same entries always return the same answer.
Worked example. A 30-year-old, 70 kg, 175 cm person has a BMR near 1,550 calories a day at complete rest.
Tips for accurate results.
BMR is at rest — add activity to get daily needs.
Use it as the floor, not your full calorie target.
Recompute after notable weight or age changes.
When to use BMR Calculator. Estimating baseline calorie burn. Setting a deficit or surplus from a known floor. Understanding why two people differ at rest.
When you actually reach for this
- You want the calories you burn at complete rest before any activity.
- You are layering activity on top of a baseline for a diet plan.
Where this tool stops being accurate
- BMR is resting burn only; multiply by an activity factor to get daily needs (that is what the calorie calculator does).
- It ignores body composition, so two people with the same stats can have different real BMR.
Frequently asked questions
What is BMR versus TDEE?
BMR is the calories you burn at complete rest, just keeping alive. TDEE adds your daily activity on top. The calculator reports the resting floor; multiply or add activity to estimate total daily expenditure, which is the figure most diet planning actually uses.
Why does sex change the result?
Because average body composition differs, the Mifflin-St Jeor formula uses a different constant for men and women, producing a different baseline. It is a population-level adjustment, not a judgment; the result is an estimate that individual variation can shift.
Is BMR a good diet target?
No — it is the minimum, not a goal. Eating at BMR long term is unsustainable because it excludes all activity. Use it as the floor and build up with your movement to find a realistic intake for losing, holding, or gaining weight.
What is the difference between BMR and TDEE?
BMR is what you burn at rest; TDEE adds your daily activity. BMR is the floor, TDEE is the realistic daily total.