Boring Tools

Calorie Needs Calculator

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Estimate daily calorie needs from age, weight, height, and activity level.

Estimate how many calories your body burns at rest (BMR) and how many you need per day at your activity level (TDEE), from your age, sex, height and weight. It is a general estimate, not medical advice.

How it works

BMR (basal metabolic rate) is calculated with the Mifflin–St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for males or − 161 for females. Feet, inches and pounds are converted to centimetres and kilograms first.

TDEE (total daily energy expenditure) is BMR multiplied by an activity factor: 1.2 for Sedentary, 1.375 for Light, 1.55 for Moderate, 1.725 for Active and 1.9 for Very active. Both results are rounded to whole numbers and given in calories (kilocalories) per day.

How to use it

  1. Choose Metric or Imperial.
  2. Enter your height, weight and age.
  3. Choose Male or Female (the formula's biological-sex term).
  4. Pick the Activity level that best describes a typical week.
  5. Read BMR and Estimated daily calories (TDEE). Click Copy to copy both.

Options & controls

Units

Metric / Imperial toggle
Switches between centimetres/kilograms and feet-inches/pounds. It is a site-wide setting shared with the other tools that use it, and remembered in this browser.

Body measurements

Height (cm)
Metric only. Default: 170.
Weight (kg)
Metric only. Default: 65.
Height (ft) and Height (in)
Imperial only; the two are added together. Default: 5 ft 7 in.
Weight (lb)
Imperial only. Default: 143.
Age (years)
Must be greater than 0. Default: 30. The same value is used in either unit system.

Sex and activity

Biological sex
Male or Female. It only changes the constant added in the formula (+5 or −161). Default: Male.
Activity level
Sedentary (little or no exercise, ×1.2); Light (1–3 days a week, ×1.375); Moderate (3–5 days a week, ×1.55); Active (6–7 days a week, ×1.725); Very active (hard exercise plus a physical job, ×1.9). Default: Sedentary.

Buttons

Copy
Copies both results as text, for example “BMR: 1,568 calories/day — TDEE: 1,881 calories/day”.
Reset
In the title row. Restores the sample body measurements, age, sex and activity (the unit system is kept).

Reading the results

Results

BMR
Calories your body would burn in a day of complete rest — breathing, circulation, keeping warm.
Estimated daily calories (TDEE)
BMR adjusted for your activity level: roughly the calories that keep your weight steady.
Assumptions & notes
A reminder of the formula and that this is not medical advice. On phones it sits behind a toggle.

Tips & guidelines

  • People commonly overestimate their activity. If you are between two levels, choose the lower one and watch your real-world results.
  • Use TDEE as a starting number, not a target. Track your weight for a few weeks and adjust up or down.
  • Each unit system keeps its own height and weight boxes, so after switching units, enter them again.
  • For any goal involving eating less or more, or for a medical condition, talk to a doctor or dietitian.

Limits

  • The formula is intended for healthy adults. It is not suitable for children, for pregnancy or breastfeeding, or for people with medical conditions affecting metabolism.
  • Individual metabolism can differ from these estimates by 10% or more.
  • The tool does not calculate calories for weight loss or gain, macronutrients, or the calories in food.
  • There are only two options for sex, and the tool has no body-fat input.

Saved in your browser

Your measurements are not saved. Only the Metric / Imperial choice is remembered in this browser, and it is shared with other tools.

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