Metabolic Age Calculator
Enter BMR and age. 1650 and age 30 give 30. 1800 and 35 give 28. 1500 and 40 give 44. The calculator compares your BMR to the estimate 1650 − 5 × (age − 30), then divides the difference by 25.
Results
Enter data and click Calculate.
Not a clinic verdict and not a lab biological age. The result is a rounded heuristic. You enter BMR. The calculator does not compute it.
How it works
Metabolic age in this calculator is age plus (reference BMR minus your BMR) / 25. The reference is 1650 − 5 × (age − 30), clipped to 1150-2100. At BMR 1650 and age 30 the gap is 0, so the result is 30 in the result. 1800 and 35 give 28. 1500 and 40 give 44.
Field a is BMR. Field b is age. The calculator does not run Mifflin. You take BMR from the BMR card or from a label. A higher BMR at the same age drops below chronological age. A lower BMR goes up.
The result is an integer, with no word years on the number. The clamp is 15 to 100. BMR 0, age 0, or BMR above 8000 leaves a dash. This is not a lab test and not a cellular age.
BMR computes a base from weight, height, age, and sex. TDEE multiplies that base by PAL. Here you stay with a ready BMR compared to a simple 1650 line. 28 at 1800 and age 35 is not a younger body from a clinic.
Enter BMR, enter age, then Calculate. A comma in 1650.5 parses. A estimate from a difference, not a doctor note and not a metabolism test.
1650 and age 30 give 30. 1800 and 35 give 28. 1500 and 40 give 44. Number formatting runs only when Format is present. The examples are a bare rounded number. Metabolic age is a heuristic, not a lab test.
met_age = round(age + (refBMR − BMR) / 25); refBMR = 1650 − 5 × (age − 30)
Age plus (refBMR minus BMR) / 25. 1650 and 30 give 30. A heuristic, not a lab test.
30
28
44
Related calculators
Common questions
What metabolic age at BMR 1650 and age 30?
The result is 30. Reference BMR at age 30 is 1650, so the gap is zero and rounding leaves 30.
What about 1800 and age 35?
The result is 28. Reference BMR at age 35 is 1625, so (1625 − 1800) / 25 = −7, and 35 − 7 = 28.
What about 1500 and age 40?
The result is 44. Reference BMR at age 40 is 1600, so (1600 − 1500) / 25 = 4, and 40 + 4 = 44.
Does the calculator compute BMR?
No. The first field takes a ready BMR in kilocalories, without weight or height. The Mifflin–St Jeor formula from those values is on the BMR page.
Is 28 a younger body?
No. A heuristic from the 1650 line. Not a lab age and not a doctor note.
What is the result range?
Rounding, then a clamp from 15 to 100. Above 8000 kcal leaves a dash.
What if BMR is 0 or age is 0?
A dash. BMR and age must be positive.
Does a comma in 1650.5 work?
Yes. 1650.5 and 30 run through the same formula.
Does a US header change 30?
No. BMR and age are not a mass. The result stays the number 30.
How does this calculator compute metabolic age?
refBMR = 1650 − 5 × (age − 30). metabolic_age = round(age + (refBMR − BMR) / 25). At 1650 and 30: 30. At 1800 and 35: 28. At 1500 and 40: 44.
Does the calculator compute BMR from weight and height?
No. The first field takes a ready BMR. Compute Mifflin on the BMR/PPM page, then paste the result here.
Does 28 mean a younger body from a clinic?
No. It is a heuristic from a BMR difference. It is not lab biological age and not a diagnosis.
How does this differ from biological age?
Biological age on CalcBoxer is a separate page with a different data set. Here only BMR is compared to a simple 1650 line.
Knowledge sources
A heuristic from the BMR you type. The calculator does not compute Mifflin; this is not a lab age.
Page updated in 2026.