MasterTool

Calorie Calculator

Work out how many calories you need per day — your BMR and maintenance calories by activity level, using the Mifflin–St Jeor equation.

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What this tool does

Work out how many calories you need per day — your BMR and maintenance calories by activity level, using the Mifflin–St Jeor equation. Same engine as this site's TDEE calculator — this page answers the 'how many calories do I need' question directly. Estimates for healthy adults; not for children, pregnancy or clinical nutrition.

How to use the Calorie Calculator

  1. Enter or select body weight in lb.
  2. Enter or select height in in.
  3. Enter or select age (years).
  4. Enter or select equation sex coefficient.
  5. Enter or select activity level.
  6. Read the calculated result; change any measurement to compare alternatives.

Formula

BMR (Mifflin–St Jeor) = 10×kg + 6.25×cm − 5×age + 5 (men) / −161 (women); maintenance calories = BMR × activity multiplier (1.2 sedentary – 1.9 athlete)
weight
Body weight (lb, before metric conversion)
height
Height (in, before metric conversion)
age
Age (years)
sex
Equation sex coefficient
activity
Activity level

Same engine as this site's TDEE calculator — this page answers the 'how many calories do I need' question directly. Estimates for healthy adults; not for children, pregnancy or clinical nutrition.

Worked example

For calorie calculator, the following measurements illustrate the exact method: Body weight: 150; Height: 67; Age (years): 30; Equation sex coefficient: male; Activity level: 1.55.

Inputs

  • Body weight150 lb
  • Height67 in
  • Age (years)30
  • Equation sex coefficientMale (+5)
  • Activity levelModerately active (exercise 3–5 days/week)

Result

  • Maintenance calories (kcal/day)2,478.47
  • BMR (kcal/day)1,599.01
  • Mild deficit −250 kcal (kcal/day)2,228.47
  • Mild surplus +250 kcal (kcal/day)2,728.47

Results explained

Maintenance calories (kcal/day)
Maintenance calories (kcal/day) from the formula above. Same engine as this site's TDEE calculator — this page answers the 'how many calories do I need' question directly. Estimates for healthy adults; not for children, pregnancy or clinical nutrition.
BMR (kcal/day)
BMR (kcal/day) from the formula above. Same engine as this site's TDEE calculator — this page answers the 'how many calories do I need' question directly. Estimates for healthy adults; not for children, pregnancy or clinical nutrition.
Mild deficit −250 kcal (kcal/day)
Mild deficit −250 kcal (kcal/day) from the formula above. Same engine as this site's TDEE calculator — this page answers the 'how many calories do I need' question directly. Estimates for healthy adults; not for children, pregnancy or clinical nutrition.
Mild surplus +250 kcal (kcal/day)
Mild surplus +250 kcal (kcal/day) from the formula above. Same engine as this site's TDEE calculator — this page answers the 'how many calories do I need' question directly. Estimates for healthy adults; not for children, pregnancy or clinical nutrition.

Frequently asked questions

For a sedentary 30-year-old man of 80 kg and 180 cm, the Mifflin–St Jeor BMR is 1,780 kcal and maintenance is 1,780 × 1.2 ≈ 2,136 kcal/day. Enter your own measurements and activity level for your figure.

Mifflin–St Jeor: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 for men, −161 for women — multiplied by an activity factor from 1.2 (sedentary) to 1.9 (athlete). It is the equation the Academy of Nutrition and Dietetics found most accurate for healthy adults.

BMR is the energy your body uses at complete rest. Maintenance calories (TDEE) add your daily activity on top — that is the intake at which weight stays roughly stable.

It uses the identical Mifflin–St Jeor engine as this site's TDEE tool. This page is framed around daily calorie needs and shows all activity levels side by side; the TDEE page centres on a single activity multiplier you enter yourself.

Equations estimate within roughly ±10% for most people; individual metabolism, body composition and activity tracking errors shift real needs. Adjust using 2–3 weeks of actual weight trend.