Adult planning estimate only. Not suitable for children, pregnancy, diagnosis, treatment, or an individualized calorie prescription. Consult a qualified clinician or dietitian for medical or nutrition decisions.
Calculation details
Adult screening estimate only, not a diagnosis. Body composition, age, pregnancy, medical history, and population-specific risk can change interpretation; discuss health decisions with a qualified clinician.
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What does this calculator estimate?
BMR and TDEE calculator: estimate your basal metabolic rate and daily calorie needs with the Mifflin St Jeor formula. Free, private, runs in your browser.
Why do BMR formulas disagree with each other?
The common equations (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle) were fitted to different populations and inputs, so they can differ by a couple hundred calories, and each carries error bars for any individual. Formulas using lean mass are sharper for muscular builds. Treat any single BMR as a center estimate; two weeks of observed weight change tells you more than the formula's precision implies.
Should I eat at my BMR or my TDEE to lose weight?
TDEE, which adds activity to BMR, is the number to compare intake against, since it reflects actual expenditure. Eating below BMR is neither required nor automatically dangerous, but very low intances are hard to sustain and defend muscle poorly. A moderate deficit from TDEE, adjusted by observed results over weeks, outperforms precise-looking targets based on a formula's false precision.
How this calculator works
Formula
Mifflin–St Jeor adult resting energy estimate: 10 × weight kg + 6.25 × height cm − 5 × age + sex term (+5 male, −161 female). TDEE multiplies estimated BMR by the selected activity factor.
Worked example
For a 30-year-old male equation term at 80 kg and 180 cm, estimated BMR is 1,780 kcal/day; a 1.2 activity factor gives about 2,136 kcal/day TDEE.
Assumptions to verify
- The equation is limited to adults age 18–100 in this tool.
- Activity multipliers are rough population planning categories, not measured expenditure.
- Pregnancy, illness, medications, body composition, adaptive metabolism, and clinical conditions are not modeled.
Frequently asked questions
Is TDEE a calorie prescription?
No. It is a planning estimate and can differ substantially from measured individual needs.
Why does the equation ask for a sex term?
The published equation contains sex-specific constants; this tool labels that mathematical input explicitly.
Who should not use this estimate alone?
Children, pregnant people, people with medical conditions, and anyone making clinical nutrition decisions should seek qualified guidance.
Cite this tool
BoringToolsKit. “BMR & TDEE Calculator.” boringtoolskit.com/bmr-tdee-calculator/ (reviewed July 2026). Free to reference in articles, syllabi, and answer posts with a link.
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