When to use this formula
Use this formula when your inputs match the variables and units shown below. It is most useful for checking a calculator result, recreating the calculation in a spreadsheet or understanding which input has the biggest effect.
Quick use
Use these formulas to compare scenarios and starting estimates, then adjust based on observed trend, qualified guidance and health context.
Formula
TDEE = BMR x activity factor; calories burned = MET x body weight x time; protein target = body weight x selected protein factor; target heart rate = resting heart rate + intensity x heart-rate reserve.
Variables
Age, sex, height, weight, activity level, exercise duration and intensity must be entered consistently. Some methods require metric units.
Method notes
- Activity factors are broad categories and often the largest source of error.
- Mifflin-St Jeor is a common BMR method for adults, but it is still an estimate.
- Exercise calorie estimates depend heavily on intensity and body mass assumptions.
Example
If estimated BMR is 1,600 and activity factor is 1.55, estimated TDEE is 2,480 calories per day.
Assumptions and limitations
These formulas do not diagnose, prescribe treatment or account for pregnancy, illness, medication, eating disorder risk, disability, elite training or individual metabolic adaptation.
When the formula is not enough
- If the result depends on live prices, rates or official thresholds, check the latest value from the named source before relying on it.
- If the topic is medical, tax, legal, lending or safety related, use the result as a learning aid and check primary guidance before acting.
- If units or time periods differ, convert them before comparing results.
- If rounding affects the decision, keep extra precision until the final step.
Common mistakes
- Treating calorie estimates as exact targets.
- Using adult formulas for children or pregnancy without specialist guidance.
- Ignoring changes in body weight, training load or symptoms over time.
References
- WHO: Healthy diet - High-level public-health context for nutrition guidance.
FAQ
Why look at the formula instead of only the answer?
The formula shows which inputs actually drive the result. That makes it easier to spot a wrong unit, compare two scenarios or explain the answer to someone else.
Can different calculators use different formulas for the same topic?
Yes. Some topics have multiple accepted methods or simplified variants. When that matters, the calculator should say which method it uses and what is excluded.
Are formula pages updated?
Stable math formulas need occasional review. Formulas that depend on changing rules, prices or thresholds need a dated source before the page can make stronger claims.