TDEE Calculator

How this is calculated

This uses the Mifflin-St Jeor equation, published in 1990 and derived from 498 healthy adults aged 19 to 78, both obese and non-obese. It is generally regarded as the most accurate of the widely used predictive equations, which is a statement about averages rather than about you. BMR = 10 x weight in kg + 6.25 x height in cm - 5 x age, then plus 5 for men and minus 161 for women. That constant is the ONLY difference between the two versions of the equation. Everything you enter is converted to metric first - pounds by 0.45359237 and inches by 2.54, both exact - so the answer is identical whichever units you pick. BMR is what you would burn lying still all day doing nothing: keeping your heart going, your temperature up and your brain running. TDEE is BMR multiplied by an activity factor - 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, 1.9 extremely active. Those factors are coarse by nature, and the gap between them is large. Moving one step up from lightly to moderately active changes the answer by around 13 percent, which is far more than the difference between any two BMR equations. Self-reported activity is also consistently overstated. If you are unsure, choose the lower of the two you are hesitating between. The biggest limitation is that this uses TOTAL body weight and cannot see body composition. Muscle burns more at rest than fat does, so a very muscular person's BMR is underestimated and someone carrying more fat at the same weight has theirs overestimated. It is the same blind spot BMI has, for the same reason - height and weight cannot tell those apart. This calculator deliberately reports what you BURN and does not prescribe what to eat. Turning a burn figure into an intake target involves goals, timelines and health conditions that no general calculator knows about.

Common questions

What is the difference between BMR and TDEE?

BMR is what your body spends existing - heart, breathing, temperature, brain - if you did nothing at all for a day. TDEE is that figure multiplied by an activity factor to account for moving, exercising, and digesting food. For most people BMR is the large majority of the total, which is usually the surprising part: staying alive costs far more than the gym does.

Which activity level should I pick?

The lower one, if you are hesitating. Self-reported activity is consistently overstated, and the factors are coarse - stepping from lightly to moderately active moves the answer by roughly 13 percent, which is bigger than the disagreement between any two BMR equations. A desk job with three gym sessions a week is 'lightly active' more often than people would like it to be; 'very active' means hard training most days or manual work.

How accurate is this?

Mifflin-St Jeor is generally considered the most accurate of the widely used predictive equations, but it was fitted to 498 people in 1990 and it describes an average rather than an individual. Real metabolic rates vary meaningfully around any prediction. Treat the number as a starting point to test against reality rather than a measurement - if your weight is stable, what you are actually eating is a better estimate of your maintenance than any equation.

Why does it use my total weight rather than my body fat?

Because the equation only takes height, weight, age and sex - it has no way to see body composition. Muscle burns more at rest than fat, so a very muscular person's BMR comes out underestimated, and someone carrying more fat at the same weight has theirs overestimated. It is the same blind spot BMI has and for the same reason. Equations that use lean mass exist and need a body-fat measurement first.

Why doesn't it tell me what to eat to lose weight?

Because that is a different question with your goals, timeline and health in it, and it deserves more than a multiplication. This calculator reports what your body BURNS. Turning that into an intake target involves choices about rate, sustainability and any medical conditions in play - which is a conversation for a doctor or a registered dietitian rather than a web page.

My weight is stable but this says I should be gaining or losing.

Then trust your weight, not the equation. A stable weight over several weeks means your actual intake IS your actual maintenance, which is a direct measurement rather than a prediction from a 1990 dataset. If they disagree by a few hundred calories that is entirely normal, and the equation is the one that should give way.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the TDEE Calculator at https://www.bfcbrilliance.com/tools/tdee-calculator.

What I entered:
- Weight: ___
- Weight in: ___
- Height: ___
- Height in: ___
- Age (years): ___
- Sex: ___
- Activity level: ___

What it calculated:
- You burn about: ___
- At complete rest (BMR): ___
- What your activity adds: ___
- Share that is just staying alive: ___
- Burned per hour at rest: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

Keep this general and do not give medical advice — where it matters, tell me what to raise with a clinician.

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