How to use this calorie calculator
Select the equation sex, enter age, height, and weight, then choose the activity description that best matches a typical week. Avoid selecting a higher level only because one workout was difficult; the multiplier represents total activity across work, transportation, household tasks, and exercise. The result shows both BMR and the multiplication used so the assumption stays visible.
How the calculation works
The first step estimates resting energy using the Mifflin–St Jeor equation. The second step multiplies BMR by a conventional activity factor from 1.2 for sedentary routines to 1.9 for exceptionally active routines. These broad labels are convenient but cannot observe actual movement or energy absorption.
Maintenance means estimated energy intake equal to estimated expenditure over time. Day-to-day scale weight also changes with water, glycogen, digestion, and other factors. NIH's Body Weight Planner uses a more detailed dynamic model for adult weight-change planning; pregnancy and breastfeeding require specialized guidance.
Formulas
Resting estimate
Maintenance estimate
Worked examples
Moderately active example
A calculated BMR of 1,600 kcal/day multiplied by 1.55 gives an estimated maintenance level of 2,480 kcal/day.
Effect of activity selection
The same 1,600 BMR multiplied by 1.2 gives 1,920 kcal/day. The 560-calorie gap shows why an honest activity classification matters more than extra decimal precision.
Common uses
Maintenance starting point
Create a rough adult baseline for meal planning or a conversation with a registered dietitian. Observe longer-term patterns rather than adjusting intake in response to one day's scale movement.
Activity scenario comparison
See how strongly broad activity categories affect the estimate. This is useful for understanding model sensitivity, not for claiming that an exercise session burned a precise amount.
Audit another estimate
Compare the visible BMR and multiplier with a fitness app or online result. A tool that uses another equation, category definition, or wearable data can reasonably produce a different answer.
Accuracy and limitations
The result multiplies a Mifflin–St Jeor BMR estimate by the exact activity factor shown in the interface. It does not measure movement, food absorption, or metabolic adaptation.
The largest practical uncertainty often comes from the activity category and individual physiology, not arithmetic rounding. This maintenance estimate is unsuitable for pediatric, pregnancy, breastfeeding, or clinical nutrition decisions.
Sources and methodology
NumUtility uses the following primary or authoritative references for this calculator. Sources explain the method; they do not turn the result into personal medical advice.
Frequently asked questions
Are maintenance calories exact?
No. They are an estimate based on body measurements and a broad self-selected activity factor. Track trends and seek professional advice when accuracy matters.
Does this calculator create a weight-loss target?
No. It estimates maintenance only. Aggressive calorie changes can be inappropriate, and personal goals should account for health, nutrition quality, and professional guidance.
What if my activity varies by day?
Choose the level that best represents a typical week. Recalculate when work, training, illness, or routine changes substantially.
Can teenagers or pregnant people use this result?
No. Growth, pregnancy, and breastfeeding have different energy requirements. Use age- and life-stage-specific professional guidance.
Are my health measurements stored?
No. Calculations run in your browser. NumUtility does not receive or save the values you enter in these tools.