Calorie Calculator

A daily calorie calculator estimates energy expenditure using a mathematical model. This tool focuses on adult resting energy and daily maintenance needs, rather than a food database or a weight-change prescription.

Daily Calorie Needs mode estimates BMR and TDEE. BMR Only mode removes the activity assumption and shows resting energy alone. Energy Unit Conversion mode converts entered kilocalories and kilojoules without requiring body measurements or an age.

1. Enter weight and height in your preferred units. Metric and imperial unit switches preserve the physical measurement.
2. Enter age in whole years. This calculator supports adult inputs from 20 to 120, with an extrapolation note above the original study’s upper age of 78.
3. Explicitly choose the +5 or −161 equation coefficient. The calculator leaves this choice blank initially.
4. Select an approximate activity level and read the estimated daily maintenance value together with the resting estimate and assumptions.

The worked-example button loads 70 kg, 175 cm, age 30, +5 and activity factor 1.55. It is a labeled demonstration, not a suggestion about your characteristics. Reset restores the starting inputs and clears the coefficient choice.

Copy, print and CSV include the selected coefficient, model, measurements and activity factor where relevant. Values are retained at full precision for calculations and exports; the daily headline rounds to a whole kcal.

Basal metabolic rate describes energy used to sustain basic functions under defined resting conditions. It excludes the additional energy used in ordinary movement, exercise and processing food.

Online calculators often use “BMR” as a familiar label for a resting estimate. Mifflin–St Jeor actually predicts resting energy expenditure (REE), which is not the same as a laboratory measurement of basal metabolism. This tool uses the familiar label while stating that distinction.

The BMR Only result is not an intake recommendation or a minimum food allowance. It is one component of an energy expenditure model.

Total daily energy expenditure combines resting energy with the energy used across daily life. A practical calculator approximation multiplies the resting estimate by an activity factor.

TDEE = estimated resting energy × activity factor. For 1,648.75 kcal/day × 1.55, the unrounded maintenance estimate is 2,555.5625 kcal/day. The headline displays 2,556 kcal/day without rounding the resting estimate before multiplication.

The difference between TDEE and the resting estimate represents a combined model allowance. It is not a direct measurement of exercise calories and should not be treated as a separate activity log.

This calculator implements the rounded form of the Mifflin–St Jeor resting energy equation:

Resting kcal/day = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + coefficient.

The coefficient is +5 for the published male equation or −161 for the published female equation. These are properties of the population model, not inferred gender identity or a complete description of physiology. A coefficient must be selected explicitly before an estimate is shown.

For 70 kg, 175 cm and age 30, the shared terms are 700 + 1,093.75 − 150 = 1,643.75. Adding +5 gives 1,648.75 kcal/day; adding −161 gives 1,482.75 kcal/day.

The original study also reported a regression using 9.99 for weight and 4.92 for age. This tool consistently uses the documented rounded 10 and 5 form, so calculations can differ slightly from implementations using the other coefficients.

The following conventional presets provide a simple approximation of daily activity. The labels describe general routines rather than exact exercise-session counts. They are not measured personal activity levels or coefficients from the original Mifflin resting-energy regression.

There is no single maintenance number shared by everyone. The daily result is a starting estimate from the supplied measurements, coefficient and activity assumption. Actual energy balance unfolds over time, and ordinary day-to-day changes do not provide a precise measurement of calorie needs.

This tool does not prescribe a deficit, surplus, restrictive intake or weight-loss timeline. If you need an individualized eating plan, particularly with a medical condition or a history of disordered eating, an appropriate professional can assess needs beyond the equation.

For a movement-specific estimate, the Walking Calories Calculator models energy expenditure during a walk. That is a different scope from daily maintenance; adding it to an activity-adjusted daily estimate can count the same activity twice.

A food Calorie, often written with a capital C, means one kilocalorie: 1 Calorie = 1 kcal = 1,000 small calories. Nutrition results here use kcal/day, not small cal/day.

Using the thermochemical calorie definition, 1 kcal = 4.184 kJ exactly. Multiply kcal by 4.184 to get kJ; divide kJ by 4.184 to get kcal. For example, 2,000 kcal is 8,368 kJ, and 418.4 kJ is 100 kcal.

The conversion mode accepts zero because zero energy is a valid unit conversion. It does not require body measurements and does not interpret the entered energy as a recommended intake. Changing direction keeps the typed number so you can enter a new amount.

Prediction equations summarize relationships observed in groups. They cannot see body composition, recent illness, medications or the details of your daily movement. A selected activity factor adds another approximation to the resting model.

The original Mifflin study included adults aged 19–78. This tool starts at 20 to maintain a consistent adult scope; results above age 78 are explicitly marked as extrapolations. Accepting an age within the tool’s input limits does not establish that the model is equally accurate for that age.

A wearable, another calculator and a clinical assessment may use different inputs, formulas or definitions. More decimal places do not remove the underlying uncertainty. A daily headline of 2,556 kcal is a rounded estimate, not evidence that exactly that intake is required.

Muscle mass, body composition, genetics, activity patterns and health circumstances can influence energy use beyond weight, height and age. The equation’s two sex-based coefficients do not capture the full range of human physiology.

Pregnancy, breastfeeding, childhood growth, illness and clinical nutrition needs require an appropriate assessment rather than a general adult maintenance calculator. This tool rejects ages below 20 and does not provide pediatric targets.

The BMI Calculator answers a separate question about weight relative to height. A BMI category does not determine a person’s calorie needs or make a diet prescription appropriate.

Method: rounded Mifflin–St Jeor resting energy, the explicitly listed approximate activity presets, and the thermochemical kcal/kJ conversion. The activity presets are a separate calculator convention; the Endotext reference below uses a different activity classification and the unrounded regression coefficients.

• Mifflin et al. (1990): original resting energy study
• Endotext: estimating resting metabolic rate
• NIST: energy and measurement conversion factors

Calculations run in your browser. Entered measurements are kept in page memory, with no measurement uploads or account required. Copy, print or export deliberately creates a result you can keep.