How to use the target bmr calculator
Prepare the values for this calculation
Algebraically solve a selected resting-energy equation for the body weight implied by a user-entered target BMR. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Resting-energy equation: choose Mifflin–St Jeor, Revised Harris–Benedict, Katch–McArdle. Match this selection to the data you enter.
- Sex term used by equation: choose Male, Female. Match this selection to the data you enter.
- Age (years): enter a value at least 18 and no more than 100 and a whole number. Use the unit named in the label or selected above. Do not leave this required field blank.
- Height (cm): enter a value at least 100 and no more than 250. Use the unit named in the label or selected above. Do not leave this required field blank.
- Body fat (%) — Katch only: enter a value at least 0 and no more than 80. Use the unit named in the label or selected above. Do not leave this required field blank.
- User-entered target BMR (kcal/day): enter a value at least 1. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Equation-implied body weight first. With the unchanged example inputs, it is 77.63 kg. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Age (years) from 35 to 39. The resulting Equation-implied body weight is 79.63 kg. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Target BMR Calculator formula
The selected published BMR equation is rearranged algebraically to solve for weight. Katch–McArdle first solves target lean mass then converts to total weight using entered body-fat percentage.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Resting-energy equation | Select an option | Mifflin–St Jeor |
| Sex term used by equation | Select an option | Male |
| Age (years) | minimum 18; maximum 100; whole number | 35 |
| Height (cm) | minimum 100; maximum 250 | 175 |
| Body fat (%) — Katch only | minimum 0; maximum 80 | 20 |
| User-entered target BMR (kcal/day) | minimum 1 | 1700 |
Worked example
Using the example inputs above, the equation-implied body weight is 77.63 kg.
- Equation-implied body weight
- 77.63 kg
- Equation
- Mifflin–St Jeor
- User-entered target BMR
- 1,700 kcal/day
Results and assumptions
This is an algebraic equation result, not a recommended body weight, calorie target, metabolic goal, or medical/nutrition prescription. Prediction equations have individual error.
Sources and method references
Fix an input or unexpected result
Age (years) is required. Enter age (years) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.