Quick answer
Maintenance calories are an estimate of how much energy you use in a day. This calculator estimates your basal metabolic rate with the Mifflin–St Jeor equation and multiplies it by an activity factor, then shows what 250 or 500 calories less or more per day would look like.
The result is an estimate for an average person with your age, sex, height and weight. Real energy use varies between people, so the sensible way to use it is as a starting point: eat near the figure for a few weeks, watch how your weight changes, and adjust.
The five activity levels use the standard multipliers 1.2, 1.375, 1.55, 1.725 and 1.9 on the basal rate.
Related tools: Macro Calculator: Split daily calories into grams of carbohydrate, protein and fat. TDEE Calculator: Total daily energy expenditure from BMR and activity level. BMR Calculator: Estimate basal metabolic rate with the Mifflin–St Jeor and revised Harris–Benedict equations.
How to use the Calorie Calculator
- Choose units: Metric (kg, cm) and Imperial (lb, in).
- Choose sex: Male and Female.
- Enter weight (kg, or lb) (between 20 and 500).
- Enter height (cm, or in) (between 50 and 250).
- Enter age (years) (a whole number, between 15 and 100).
- Choose activity level: Sedentary (little or no exercise), Light (1–3 days/week), Moderate (3–5 days/week), Very active (6–7 days/week) and Extra active (physical job + training).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Units | Choose one: Metric (kg, cm); Imperial (lb, in) | Starts at Metric (kg, cm) |
| Sex | Choose one: Male; Female | Starts at Male |
| Weight (kg, or lb) | A number | ≥ 20, ≤ 500 |
| Height (cm, or in) | A number | ≥ 50, ≤ 250 |
| Age | A whole number, in years | ≥ 15, ≤ 100 |
| Activity level | Choose one: Sedentary (little or no exercise); Light (1–3 days/week); Moderate (3–5 days/week); Very active (6–7 days/week); Extra active (physical job + training) | Starts at Sedentary (little or no exercise) |
Formula and method
Formula
Maintenance = BMR (Mifflin–St Jeor) × activity factor; goals add or subtract 250 or 500 kcal
IEEE-754 double precision; shown to 1 decimal place unless stated.
Maintenance calories with simple deficit/surplus targets. Informational estimate, not medical advice. Talk to a qualified health professional about your own situation.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Units = Metric (kg, cm); Sex = Male; Weight (kg, or lb) = 70; Height (cm, or in) = 175; Age = 30; Activity level = Moderate (3–5 days/week).
| Result | Value |
|---|---|
| Maintenance calories | 2,556 kcal/day |
| Mild weight loss (−250) | 2,306 |
| Weight loss (−500) | 2,056 |
| Mild weight gain (+250) | 2,806 |
| Weight gain (+500) | 3,056 |
Example 2
Inputs: Units = Metric (kg, cm); Sex = Male; Weight (kg, or lb) = 70; Height (cm, or in) = 175; Age = 30; Activity level = Sedentary (little or no exercise).
| Result | Value |
|---|---|
| Maintenance calories | 1,979 kcal/day |
| Mild weight loss (−250) | 1,729 |
| Weight loss (−500) | 1,479 |
| Mild weight gain (+250) | 2,229 |
| Weight gain (+500) | 2,479 |
The first line is the headline result (maintenance calories). Below it the calorie Calculator lists mild weight loss (−250), weight loss (−500), mild weight gain (+250) and weight gain (+500), which describe the same case from other angles. IEEE-754 double precision; shown to 1 decimal place unless stated.
The Mifflin–St Jeor equation
Basal metabolic rate (BMR) in kilocalories per day is 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for men or − 161 for women.
For a 30-year-old man who weighs 70 kg and is 175 cm tall: 10 × 70 = 700, 6.25 × 175 = 1,093.75, 5 × 30 = 150, so BMR = 700 + 1,093.75 − 150 + 5 = 1,648.75 kcal. Multiplying by 1.55 (moderate activity) gives 2,555.6, shown as 2,556 kcal per day; with the 1.2 sedentary factor it is 1,978.5, shown as 1,979.
Reading the goal lines
The goal lines subtract or add a fixed 250 or 500 calories per day to the maintenance figure. They are simple arithmetic, not a plan. A large deficit is not suitable for everyone, so check with a qualified health professional before cutting calories sharply.
How the result changes with weight
Holding every other input at the first worked example, this table changes only weight. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Weight | Maintenance calories | Mild weight loss (−250) | Weight loss (−500) |
|---|---|---|---|
| 35 | 2,013 kcal/day | 1,763 | 1,513 |
| 70 | 2,556 kcal/day | 2,306 | 2,056 |
| 140 | 3,641 kcal/day | 3,391 | 3,141 |
| 280 | 5,811 kcal/day | 5,561 | 5,311 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Age: entering "5" shows "Age must be at least 15." beside that field and no result.
Choosing between the Calorie Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Macro Calculator](/health/macro-calculator/) | daily calories, carbohydrate and protein | Carbohydrate |
| [TDEE Calculator](/health/tdee-calculator/) | units, sex and weight | Total daily energy expenditure |
| [BMR Calculator](/health/bmr-calculator/) | units, sex and weight | Basal metabolic rate |
| [Calorie Deficit Calculator](/health/calorie-deficit-calculator/) | units, weight to lose and time | Daily calorie deficit |
| [Calorie Density Calculator](/health/calorie-density-calculator/) | calories and weight | Calorie density |
Background: nutrition estimates
Nutrition calculators estimate: they use population-average equations and food tables, and different tables give different numbers for the same food. Certain medical conditions change energy needs in ways basic formulas cannot see, and only laboratory analysis gives exact nutrient values.
Use the result as a starting point, track what actually happens over a few weeks and adjust; ask a qualified professional about medical or clinical decisions.
Assumptions and limitations
- Do not go below medically advised minimums
- Not a diagnosis
This calculator gives general information based on published formulas. It is not medical advice, and it cannot account for your health history. Talk to a qualified clinician about decisions that affect your health.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for age to confirm this.
Frequently asked questions
How many calories do I need per day?
Enter your sex, age, height, weight and activity level. The calculator estimates the calories that hold your weight steady (maintenance) using the Mifflin–St Jeor equation times an activity factor.
Which equation does the calorie calculator use?
It uses the Mifflin–St Jeor equation (Mifflin et al., Am J Clin Nutr 1990) for basal metabolic rate, with standard activity multipliers from 1.2 to 1.9.
What does the Calorie Calculator calculate?
Daily calories to maintain, lose or gain weight. It returns Maintenance calories, Mild weight loss (−250), Weight loss (−500), Mild weight gain (+250) and Weight gain (+500).
What formula does the Calorie Calculator use?
Maintenance = BMR (Mifflin–St Jeor) × activity factor; goals add or subtract 250 or 500 kcal. Maintenance calories with simple deficit/surplus targets.
What do I need to enter in the calorie Calculator?
You enter Units, Sex, Weight (kg, or lb), Height (cm, or in), Age (years) and Activity level.
How is the result rounded or limited?
IEEE-754 double precision; shown to 1 decimal place unless stated. Do not go below medically advised minimums.
What are the limits of this calculator?
Do not go below medically advised minimums. Not a diagnosis.
What does the “Units” option change?
It sets how the calorie is worked out. The choices are Metric (kg, cm) and Imperial (lb, in).
What is an example of a calorie result?
With units Metric (kg, cm), sex Male, weight (kg, or lb) 70, height (cm, or in) 175 and age 30, the maintenance calories is 2,556 kcal/day.
Where does the method come from?
The method follows: Mifflin MD et al., Am J Clin Nutr 1990;51:241–247; Roza AM, Shizgal HM, Am J Clin Nutr 1984;40:168–182 (revised Harris–Benedict).
Can I rely on this calculator for a decision?
This calculator gives general information based on published formulas. It is not medical advice, and it cannot account for your health history. Talk to a qualified clinician about decisions that affect your health. For this calculator in particular: Do not go below medically advised minimums.
Related calculators
- Macro Calculator — Split daily calories into grams of carbohydrate, protein and fat.
- TDEE Calculator — Total daily energy expenditure from BMR and activity level.
- BMR Calculator — Estimate basal metabolic rate with the Mifflin–St Jeor and revised Harris–Benedict equations.
- Calorie Density Calculator — Calories per gram of a food.
- Push-Up Calorie Calculator — Calories burned doing push-ups (calisthenics) for a given effort level and time.
- Fat Intake Calculator — Daily fat range from calorie intake.
- Fiber Calculator — Daily fiber target from calorie intake.
Sources
- Mifflin MD et al., Am J Clin Nutr 1990;51:241–247
- Roza AM, Shizgal HM, Am J Clin Nutr 1984;40:168–182 (revised Harris–Benedict)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.