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Calorie Calculator

Estimate the daily calories you need to maintain, lose, or gain weight using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle and your activity level.

Maintained by CalculatorBuddy TeamEditorial methodology

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US Units

ExampleSample values — edit any field to see your result.

years

Adults 18–80 only. Not for pregnancy, breastfeeding or medically supervised nutrition.

Gender
ft
in
lb

Do not use weight-change estimates during pregnancy/breastfeeding, with an eating disorder, or when a clinician manages your nutrition. Confirm only if none applies.

Results update as you type.

Estimated energy needs (BMR if selected)

2,515Cal/day

Estimated result

Eligibility and limits
Energy estimate only. Confirm adult eligibility before viewing weight-change estimates. Not for pregnancy, breastfeeding, eating disorders or clinical nutrition needs.

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Compare scenarios

Keep a baseline, then change an assumption to see its effect side by side.

Estimated energy needs (BMR if selected)2,515 Cal/day

Estimate how many calories you need each day to maintain your weight, plus the eligible adult weight-change scenarios, without promising a rate of change. Enter your age, sex, height, weight, activity level, and BMR formula in US or metric units.

Examples

Man, 30, 180 cm, 80 kg, moderate activity

BMR is 1,780 calories. At the moderate factor (1.465) maintenance is about 2,608 calories/day. After confirming eligibility, a 500 Cal/day deficit scenario is about 2,108 and a 500 Cal/day surplus is about 3,108. Neither predicts a particular weekly weight change.

Formula

First your basal metabolic rate (BMR) is found with Mifflin-St Jeor (the default), Revised Harris-Benedict, or Katch-McArdle, then scaled by activity to get maintenance calories (TDEE). Choose Basal Metabolic Rate (BMR) as the activity level to see BMR itself (factor 1.0). Mifflin-St Jeor:

Men:   BMR = 10·weight(kg) + 6.25·height(cm) − 5·age + 5
Women: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age − 161
TDEE  = BMR × activity factor
Activity levelFactor
Basal Metabolic Rate (BMR)1.0
Sedentary (little or no exercise)1.2
Light (1–3 days/week)1.375
Moderate (4–5 days/week)1.465
Active (daily, or intense 3–4 days/week)1.55
Very Active (intense 6–7 days/week)1.725
Extra Active (very intense daily, or physical job)1.9

Weight-change scenarios use 250 or 500 Cal/day adjustments only after eligibility confirmation. Deficits are hidden for BMI below 18.5, when BMR-only activity is selected, when a target is below 1,500 Cal/day, or when the deficit exceeds 20% of estimated daily needs. No extreme-loss target is provided.

For adults ages 18–80 only. Not for pregnancy, breastfeeding, eating disorders or clinical nutrition needs. Seek individual professional guidance in these situations. BMR is resting energy expenditure, not an intake recommendation. The safeguards are product limits, not proof that a displayed target is suitable.

Sources

Frequently asked questions

What are maintenance calories?
Maintenance calories (your TDEE — Total Daily Energy Expenditure) are the number of calories that keep your weight stable. Eat fewer to lose weight, more to gain. It's your BMR multiplied by an activity factor.
How many calories should I eat to lose weight?
Eligible adults may see 250 and 500 calorie adjustments as illustrative scenarios. They do not guarantee a weekly weight change because metabolism, activity, water, and body composition change over time.
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) is the energy your body uses at complete rest. TDEE is BMR scaled up by your activity level — it's what you actually burn in a day and what this calculator reports as maintenance calories.
How accurate is the calorie calculator?
It defaults to the Mifflin-St Jeor equation and also supports Revised Harris-Benedict and Katch-McArdle. Every result is still an estimate — real needs vary with body composition, genetics, and exact activity, so adjust based on how your weight responds.
Is it safe to eat very few calories?
Very low intakes can be unsafe. This tool hides deficit targets below 1,500 Cal/day or exceeding 20% of estimated daily needs. These conservative product safeguards do not establish a safe intake for any individual.

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