Resting energy and maintenance, explained
Resting energy, often called BMR, estimates the energy your body uses at rest. This tool uses the published Mifflin–St Jeor equation. Maintenance energy adds daily movement and exercise using an activity factor. Both are estimates; an activity label cannot measure your exact expenditure.
BMR is not a universal minimum food intake. A suitable intake depends on nutrition, health and personal circumstances. The tool avoids goals below 1,200 kcal and weight-loss planning for measurements indicating a low BMI. These are general tool guardrails, not a declaration that every other target is appropriate.
Choose a goal and divide your day
Maintenance uses the estimated daily expenditure. A loss or gain goal adjusts it by a percentage you choose, from 0% to 25%. This helps the adjustment scale with the size of the estimate. The weekly budget is seven daily targets, not a promise of a particular weight change.
- Switch between metric and imperial measurements; valid height and weight values are converted.
- Display energy in calories (kcal) or kilojoules (kJ). One kcal equals 4.184 kJ.
- Choose an example nutrient split or customise protein and fat percentages. Carbohydrate fills the remainder.
- Divide the daily target across three to five meals or snacks. Custom meal percentages must total 100%.
- Optionally enter calories already eaten to compare with today's budget.
- Copy your plan to use it elsewhere.
Check the estimate against real observations
The optional trend check compares average intake with the change between two weight averages across 14–90 days. It uses a rough energy-balance approximation of 7,700 kcal per kilogram and lets you choose whether to use that estimate as your maintenance value.
Water shifts, muscle changes, food tracking errors and metabolic adaptation can distort the result. Use averages collected consistently, review the trend over several weeks, and avoid treating this rough check as a clinical measurement or future-weight forecast. For a detailed weight-goal model, the NIH Body Weight Planner is linked above.
What the nutrient split means
The split uses percentages of total energy. Carbohydrate and protein are converted using 4 kcal per gram, and fat using 9 kcal per gram. Displayed grams are rounded, so a reconstructed total from those rounded numbers can differ slightly.
The general adult reference ranges are carbohydrate 45–65%, protein 10–35% and fat 20–35% of energy. The tool highlights splits outside these ranges. Example splits are illustrations; they do not replace advice tailored to your health, training or dietary needs.
Frequently asked questions
›How many calories should I eat?
The maintenance estimate is a starting point based on your profile and typical activity. Choose a modest goal adjustment if appropriate, then review actual intake and weight averages. Health conditions or specialised nutrition needs require individual guidance.
›Can I enter pounds and feet?
Yes. Switch to lb / ft + in. Valid measurements are converted when you switch units, so you do not need to calculate the conversion yourself.
›Does a calorie deficit guarantee a fixed weekly loss?
No. Energy needs, water weight and metabolic adaptation change over time. This tool shows an energy budget and does not predict a fixed weekly loss or a date when you will reach a weight goal.
›Can I customise my macros and meals?
Yes. Set protein and fat percentages; carbohydrate uses the remainder. Choose three to five meals or snacks and edit their names and percentages. Meal percentages must add up to 100%.
›Why does the tool show a low-target warning?
It avoids targets below 1,200 kcal and weight-loss planning when the entered measurements indicate a low BMI. These are general planning guardrails. A registered dietitian can assess needs the tool cannot safely individualise.
›Is my plan automatically saved?
No. Your current inputs last for this visit. Copy result keeps the calculation on your clipboard. The page Share icon sends only a link to the tool, without your profile or plan.