Calorie calculator: resting energy and activity scenarios

Explore a Mifflin–St Jeor resting-energy estimate, an activity-adjusted maintenance scenario, and illustrative lower and higher energy scenarios. These estimates are educational, not individualized eating targets.

How to use this calculator

Choose Metric or Imperial, then an equation profile. Adjust the age, weight and height sliders and select an activity category. Results update automatically; there is no Calculate or Clear button. The widget currently accepts ages 14–90, but the equation and this page are intended for adult education. Under-18 users should not use the goal scenarios to set intake. Reloading returns the demonstration values.

Resting energy and total daily energy are different

The large BMR number uses the Mifflin–St Jeor resting-energy equation. The maintenance scenario multiplies that unrounded value by the selected activity factor: 1.2, 1.375, 1.55, 1.725 or 1.9. Those broad categories are assumptions, not a measurement of your movement or metabolism. The result may differ substantially from individual needs.

The formula, made visible

Resting estimate = 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then +5 for the male equation or −161 for the female equation. The profiles reflect the published equation and are not a complete description of sex, gender or physiology. Maintenance = resting estimate × activity factor. The lower scenario is maintenance × 0.8 (20% lower), and the higher scenario is maintenance × 1.1 (10% higher). These extra multipliers are illustrative conventions, not part of the original Mifflin validation.

A worked example

For age 30, 70 kg, 175 cm and the male equation, resting energy is 1648.75 kcal/day, displayed as 1649. At activity factor 1.55, maintenance is 2555.5625, displayed as 2556. The 20% lower and 10% higher scenarios display 2044 and 2811. With the female equation, the resting result is 1482.75, displayed as 1483. These are arithmetic examples, not recommended intakes.

Why the estimate can differ from your needs

Predictive equations estimate patterns rather than measure your metabolism. Body composition, measurement error, medication, illness and circumstances outside the source study can affect results. Activity multipliers add another layer of uncertainty. Choosing a category because of workout frequency alone can overlook occupational activity and the rest of the day.

When this tool is not enough

Do not use this calculator to set intake for children or adolescents, pregnancy or breastfeeding, eating-disorder concerns, or medical nutrition therapy. The widget permits some adolescent ages, but that interface range does not establish suitability. The labels Lose fat and Build describe the direction of the arithmetic scenarios; they do not guarantee an outcome or establish safe intake. Ask an appropriately qualified professional for an individual plan.

Should I eat the maintenance or goal number exactly?

No. Every number is an estimate or a hypothetical adjustment. The calculator does not assess nutrient adequacy, growth, recovery, health conditions or whether changing weight is appropriate. A percentage below maintenance can be unsuitable even when the arithmetic is correct. Avoid turning any result into a rigid rule.

How should I interpret activity and goal adjustments?

The activity factors are selectable scenarios, not clinical measurements. The lower scenario subtracts 20% and the higher scenario adds 10% from the activity-adjusted estimate. The original resting-energy publication does not validate these adjustments as a personal diet plan. Use the controls to understand sensitivity to assumptions, and seek qualified guidance for personal targets.

Are my inputs saved?

The embedded calculator runs in this browser tab and does not submit its entered values. Switching units keeps an internal metric value; imperial sliders display whole pounds and inches, so the displayed label and internal value may differ slightly after conversion. Refreshing clears the current choices. Website logs, analytics and third-party assets are separate from this calculator; see the privacy notice.

Sources and editorial scope

Resting equation: Mifflin et al., A new predictive equation for resting energy expenditure in healthy individuals (1990). Activity factors and ± percentage scenarios are disclosed assumptions, not outcomes established by that paper. Prepared with AI assistance; no independent clinical review is claimed. Last checked: 9 October 2026. Read the editorial policy and educational disclaimer.

A practical next step

For practical food organization, use the meal planner. Explore percentage-to-gram arithmetic with the macro calculator, browse Nutrition tools, or build a flexible weekly routine.