Waist to Height Ratio
The measure BMI structurally cannot give you.
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BMR & TDEE Calculator
Resting burn and daily needs, with the error bars shown.
What it does. BMR is what you burn at complete rest — roughly 60 to 70% of daily energy use. TDEE multiplies that by an activity factor. The BMR equation is accurate to about 10% for most people; the activity multiplier is far rougher, and it is where nearly all the error enters.
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How to use BMR & TDEE Calculator
- Enter age, sex, height and weight.
- Pick the activity level that matches a typical week.
- Read BMR, TDEE and the range around it.
Which equation and why
Mifflin-St Jeor, published in 1990, is the one used here. It outperformed the older Harris-Benedict equation on modern populations and is the default recommendation of most dietetic bodies.
It predicts measured resting energy expenditure within 10% for roughly 80% of people — which also means one person in five falls outside that.
Katch-McArdle is better if you know your body fat percentage, because it works from lean mass and so does not need to guess at composition from height and weight. It needs a measurement most people do not have.
The activity multiplier is the weak link
| Level | Multiplier | What it means |
|---|---|---|
| Sedentary | 1.2 | Desk job, little deliberate exercise |
| Lightly active | 1.375 | Light exercise 1–3 days a week |
| Moderately active | 1.55 | Moderate exercise 3–5 days |
| Very active | 1.725 | Hard exercise 6–7 days |
| Extra active | 1.9 | Physical job or twice-daily training |
These are coarse buckets, and people consistently place themselves a band too high. A step between bands is 150 to 300 calories a day — larger than the difference most people are trying to measure.
Treat the result as a starting point
The honest way to use a TDEE number is as a hypothesis. Eat at it for two or three weeks, track weight, and adjust from what actually happens.
Your own trend line beats any equation, because it accounts for your real activity, your real portions and your own metabolism rather than a population average.
Weight also moves for reasons unrelated to energy balance — glycogen, sodium, hydration and menstrual cycle can swing the scale by a kilo or more within a day. Use a weekly average, not single readings.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest, about 60 to 70% of daily energy use. TDEE is BMR multiplied by an activity factor to cover movement, exercise and digestion.
How accurate is a TDEE calculator?
The BMR part predicts measured values within about 10% for four people in five. The activity multiplier is much rougher and contributes most of the error — one band is 150 to 300 calories a day.
Which equation is best?
Mifflin-St Jeor for most people, and it is what this uses. Katch-McArdle is better if you know your body fat percentage, because it works from lean mass instead of inferring composition.
Why did my weight not move at my calculated TDEE?
Because it is a population estimate, not your measurement. Eat at it for two to three weeks, track a weekly average, and adjust from the trend — your own data beats any equation.
Should I eat below my BMR to lose weight?
That is a question for a doctor or dietitian rather than a calculator. Very low intakes are used clinically but under supervision, and this tool has no way to know anything about your health.