BMR and daily energy estimator
Estimate resting energy with the Mifflin–St Jeor equation and compare a user-selected activity scenario.
Your inputs
Your results
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How it works
Explore the simplified Mifflin–St Jeor resting energy equation and see how an editable daily-energy multiplier changes the numerical scenario. The tool displays REE separately from assumed whole-day energy to avoid presenting resting expenditure as a recommended intake.
A few things to know
For educational use within the original 19–78 age range. Excludes pregnancy, breastfeeding and clinical illness assessment. Two original sex coefficients do not model all individual physiology. Measurement bounds are usability checks, not evidence of validity throughout those ranges. Multipliers are assumptions; no activity assessment, weight trajectory, dietary prescription or individual error interval is calculated.
When to use this tool
A resting energy prediction and a whole-day energy estimate answer different questions. This BMR calculator keeps them separate: it uses the simplified Mifflin–St Jeor equation for resting energy expenditure, then multiplies that prediction by an editable assumption to show a daily-energy scenario. A small comparison table makes the influence of the multiplier visible. Use it to understand the calculation and its sensitivity, rather than to prescribe calories, plan a deficit or predict weight change.
- Reproduce the arithmetic of the Mifflin–St Jeor equation with transparent units and coefficients.
- Compare daily-energy scenarios while holding the resting estimate constant.
- Distinguish a numerical prediction from a measured metabolic assessment or an intake recommendation.
How to use bmr and daily energy estimator
Enter metric measurements and age
Use weight in kg, height in cm and age in whole years. The form accepts ages 19–78, matching the original study’s age range. Convert other units before entering them.
Select an equation coefficient
Choose one of the two coefficients used in the original study. Check the assessment context; pregnancy, breastfeeding and clinical illness assessment are outside this tool’s scope.
Inspect the multiplier assumption
Enter a daily-energy multiplier from 1 to 2.5. Read resting kcal/day first, then the multiplied scenario and comparison table. The default 1.4 is an illustration, not an assessment of your activity.
A resting estimate with a 1.4 scenario multiplier
Inputs
Weight 70 kg; height 175 cm; age 30; male equation coefficient +5; multiplier 1.4; eligible assessment context.
Result
The unrounded resting estimate is 1,648.75 kcal/day and the scenario is 2,308.25 kcal/day. The screen rounds these to 1,648.8 and 2,308.3 kcal/day.
What it means
At multiplier 1.6, the same resting estimate produces 2,638.0 kcal/day. That difference comes entirely from changing an assumption; it does not establish either figure as the person’s measured expenditure or recommended food intake.
Common mistakes to avoid
Reading resting energy as a calorie allowance
The resting prediction omits the separate daily-energy multiplier. Neither output is a dietary prescription or a minimum safe intake.
Guessing activity with false precision
Entering 1.437 does not make a scenario more accurate than 1.4. The multiplier is user supplied, and the tool does not assess occupation, training or day-to-day variation.
Assuming every adult was represented
The original prediction study does not establish applicability to every condition or physiology. Staying inside the age and input bounds does not guarantee personal accuracy.
Frequently asked questions
Definitions, edge cases, and practical next steps for this tool. Search all tool FAQs ↗
What formula is used?
The simplified equation is 10 times weight in kg, plus 6.25 times height in cm, minus 5 times age, plus the selected coefficient. The male coefficient is +5 and the female coefficient is −161. The result is expressed in kcal per day.
Why does the result say REE when the page says BMR?
BMR is a familiar search term, but the original Mifflin–St Jeor paper predicts resting energy expenditure, or REE. The result uses that more precise label. A calculated resting prediction should not be presented as a directly measured basal metabolic rate.
What does the daily-energy multiplier mean here?
It scales the resting prediction into a whole-day scenario. NIDDK’s separate planner describes typical physical activity levels around 1.4–2.5. This tool does not implement that planner or infer a personal level; it simply multiplies by the value you enter.
Can I use the result as a weight-loss calorie target?
This calculator does not calculate a deficit, model changing weight or recommend intake. Subtracting a fixed amount would add a separate assumption unsupported by this tool. Seek appropriate professional guidance for a personal dietary plan.
Who was the original equation developed from?
The paper used 498 healthy participants aged 19–78. Those cohort details describe where the model came from, not a guarantee for every person with similar measurements. The tool rejects ages outside that range rather than silently extrapolating.
Why are there only two coefficient options?
Those are the two equations published in the original study. The calculator exposes that limitation instead of inventing another validated coefficient. It does not resolve which equation applies to every individual physiology or clinical situation.
Are the displayed decimals an accuracy claim?
No. One decimal place is a display choice. Input measurements, model error and the multiplier assumption can matter far more than that final digit. The tool calculates no individual confidence interval and makes no guarantee of closeness to a measured value.
What is the difference between kcal and kJ?
They are different energy units. This calculator uses 4.184 kilojoules per kilocalorie and shows the resting estimate in both units. Keep the per-day period consistent when comparing figures; changing units does not change the underlying predicted energy.
Explore the topic in the blog
Sources and method
Use the references below to check definitions and platform guidance. The model’s scope and limits are explained above. Read our editorial standards.