# TDEE Calculator

> Work out your resting metabolic rate with the Mifflin-St Jeor equation and your total daily energy expenditure at each of five activity levels, so you can see how much of the answer depends on the one thing you had to guess. The equation, its accuracy and its limits are published below.

Use it: https://tessalor.com/en/health/tdee-calculator

This tool runs entirely in the browser. Nothing entered into it is uploaded.

## Formula

```
Mifflin-St Jeor (1990), resting metabolic rate in kcal per day:

  men    BMR = 10 x weight + 6.25 x height - 5 x age + 5
  women  BMR = 10 x weight + 6.25 x height - 5 x age - 161

where
  weight = kilograms
  height = centimetres
  age    = years

Total daily energy expenditure:

  TDEE = BMR x activity multiplier

  1.200  sedentary
  1.375  lightly active
  1.550  moderately active
  1.725  very active
  1.900  extremely active

Calorie target for a chosen rate of weight change:

  target = TDEE + (kg per week x 7700 / 7)

  floored at 1200 kcal (women) and 1500 kcal (men)
```

## Assumptions

- The equation predicts a group average rather than you. Frankenfield's systematic review found it the most reliable of the equations tested, estimating resting rate to within 10% of a measured value more often than any other, while noting that errors and limitations remain.
- The activity multiplier is a self-assessment and it is the largest source of error here. Each rung of the ladder is 0.175 of your resting rate away from the next, which is about 240 calories a day for the worked example below.
- Body composition is ignored. The equation takes total body weight, so it tends to underestimate a muscular person and overestimate somebody carrying more fat at the same weight.
- Weight change is converted at 7,700 kcal per kilogram. That holds for a few weeks and then overstates the loss, because maintenance falls as you get lighter.
- The calorie target is never displayed below 1,200 kcal for women or 1,500 for men. Those are the top of the range the NHLBI's 1998 clinical guidance prescribes for a low-calorie diet, used here as a floor.
- Nothing here accounts for pregnancy, breastfeeding, a thyroid condition, or medication that changes metabolic rate. It is not intended for anyone under 18.
- Calorie means kilocalorie throughout, which is what a food label in Britain prints as kcal and an American one prints as Calories.

## Inputs

| Name | Label | Type | Default | Range |
| --- | --- | --- | --- | --- |
| `sex` | Sex | select | female |  |
| `age` | Age | integer | 30 | 18 to 100 |
| `height` | Height | number | 165 | 120 to 230 |
| `weight` | Weight | number | 65 | 30 to 300 |
| `activity` | How active you are | select | 1.55 |  |
| `pace` | Weight you want to change | select | 0 |  |

## Outputs

- `tdee` — Calories to maintain your weight (number), primary
- `bmr` — Resting rate (BMR) (number)
- `activityBurn` — Everything above resting (number)
- `targetCalories` — Calories for your chosen pace (number)

## Questions

### Why does every calorie calculator give me a different number?

Two reasons. Some use a different resting-rate equation — Harris-Benedict from 1919, Katch-McArdle if you have supplied a body fat figure — and those differ from Mifflin-St Jeor by 50 to 150 calories for a typical adult. The larger reason is the activity multiplier, which is a self-assessment: one rung of the ladder is worth about 240 calories a day, so two honest people describing the same week can land 500 apart.

### What is the difference between BMR and TDEE?

BMR is what your body uses at complete rest — breathing, circulation, keeping your organs running — and it is typically 60 to 70% of the total. TDEE adds everything else: walking about, deliberate exercise, and the energy cost of digesting food. TDEE is the figure to compare against what you eat.

### Which activity level should I pick?

Pick the lower of the two you are torn between. The ladder describes your whole week rather than your best week, and the multiplier already includes ordinary daily movement, so a desk job with three gym sessions is lightly to moderately active, not very active. Getting this wrong in the optimistic direction is the single most common reason a calorie target does not work.

### Is Mifflin-St Jeor better than Harris-Benedict?

For most adults, yes. Frankenfield's 2005 systematic review compared the published equations against measured resting rates and found Mifflin-St Jeor landed within 10% of the measurement more often than any other, which is why it became the default in dietetic practice. It still carries noteworthy errors and limitations, and the review says so in as many words.

### Why is there no option other than female and male?

Because the paper published two constants and no third one exists to use. Adding an average of the two would be inventing a figure and presenting it as a measurement. If neither fits, the honest reading is to run it both ways and treat the 166-calorie gap between them as the uncertainty.

### Are my height, weight and age sent anywhere?

No. The arithmetic runs in this browser tab and there is no server to send it to. Your height, weight and age never leave the device, which is the reason this page has no account and asks for no email.

## Sources

- [A new predictive equation for resting energy expenditure in healthy individuals](https://pubmed.ncbi.nlm.nih.gov/2305711/) — American Journal of Clinical Nutrition, applies to 1990. Retrieved 2026-07-30.
- [Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review](https://pubmed.ncbi.nlm.nih.gov/15883556/) — Journal of the American Dietetic Association, applies to 2005. Retrieved 2026-07-30.
- [Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: Treatment Guidelines](https://www.ncbi.nlm.nih.gov/books/NBK2004/) — National Heart, Lung, and Blood Institute, applies to 1998. Retrieved 2026-07-30.
- [Quantification of the effect of energy imbalance on bodyweight](https://pubmed.ncbi.nlm.nih.gov/21872751/) — The Lancet, applies to 2011. Retrieved 2026-07-30.
- [Human energy requirements. Report of a Joint FAO/WHO/UNU Expert Consultation](https://www.fao.org/4/y5686e/y5686e00.htm) — Food and Agriculture Organization of the United Nations, applies to 2004. Retrieved 2026-07-30.

## Variants

- [How many calories should I eat to lose 0.5 kg a week?](https://tessalor.com/en/health/tdee-calculator/to-lose-half-a-kilo-a-week)
- [How many calories do I need a day with a desk job?](https://tessalor.com/en/health/tdee-calculator/with-a-desk-job)

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