How to Calculate TDEE with Mifflin–St Jeor
TDEE is the calories you burn in a day: BMR times an activity factor. The tool computes BMR, scales it by the activity level you pick, then shows a fat-loss reference 400 kcal lower.
A starting point for intake
Whether the goal is losing, gaining or maintaining, the first number you need is what maintenance looks like. At 65 kg, 172 cm and 30 years old, BMR is about 1,580 kcal; with three sessions a week (1.375) TDEE is roughly 2,173 kcal, and the fat-loss reference lands near 1,773 kcal. Eat near that figure and weight should hold roughly steady.
Treat that as a starting point rather than an answer. Track weight and waist for two weeks, then adjust by 100–200 kcal based on whether the trend matches the goal. BMR falls as weight falls, so recalculate after roughly every 5 kg lost, and keep protein and resistance training in the plan to protect muscle.
- Set a maintenance intake
- Pick a starting deficit for fat loss
- Add 200–300 kcal for a lean gain phase
Formula, activity factor and sex
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. The final +5 is the male variant; the female variant ends in −161, a difference of 166 kcal. The tool has no sex switch and always uses the male form, so women should subtract about 166 kcal.
Choose the activity factor for the whole day, not the training hour: 1.2 sedentary, 1.375 light (1–3 sessions a week), 1.55 moderate (3–5), 1.725 very active (6–7), 1.9 extremely active or manual work. One level too high adds 100–200 kcal and quietly slows fat loss.
- Female users subtract about 166 kcal
- Judge activity across the whole day
- Results are whole numbers, so small rounding applies
Why it remains an estimate
The equation comes from population averages, and individual variation reaches roughly ±10%. Body composition, thyroid function, medication and genetics all move real expenditure; two people of the same height and weight can differ by 300 kcal or more.
It is not appropriate during pregnancy or breastfeeding, for children and adolescents, for people with a history of eating disorders, or for physique athletes in contest prep. For measured data, use indirect calorimetry, or back-calculate from two weeks of intake and weight change. Ask a clinician if a condition or medication is involved.
- Calibrate with two weeks of weight data
- Not for pregnancy, breastfeeding or minors
- Medical conditions need professional advice
FAQ
Why is the result high for women?
The tool always applies the male equation, which ends in +5. The female equation ends in −161, so the gap is 166 kcal. Women should subtract that from BMR, TDEE and the fat-loss figure before using them.
How do I choose between 1.375 and 1.55?
Look at the whole day. Desk work plus three gym sessions usually fits 1.375; frequent walking plus four or five sessions gets closer to 1.55. When unsure, pick the lower level, check two weeks of weight data, then adjust.
Why a 400 kcal deficit?
It is a moderate reference gap that supports gradual loss without constant hunger. It is not a prescription and does not guarantee a specific rate of loss. Persistent fatigue, poor sleep or disrupted cycles are reasons to shrink the gap or seek advice.
Related tool：TDEE Calculator