To calculate BMR for women, use the female Mifflin–St Jeor equation: BMR (kcal/day) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161, which estimates the calories a woman’s body is expected to use at complete rest to sustain essential functions. For the quickest practical method, open the BMR Calculator, enter sex, age, weight, and height, and read the primary result; the tool places the revised Harris–Benedict estimate beside it for context. BMR means Basal Metabolic Rate: the energy needed for work such as breathing, circulation, brain activity, and cell repair, before movement, digestion, or exercise is added. It is a baseline, not a complete daily calorie target. The female formula uses four basic personal inputs—sex, age, weight, and height—because laboratory measurement is difficult and prediction equations provide an accessible estimate from those characteristics. The calculator uses the Mifflin–St Jeor equation, published in 1990, for its primary result, which is rounded to the nearest whole calorie. The second result comes from the 1984 Roza and Shizgal revision of Harris–Benedict. Seeing both makes uncertainty visible: equations are built from population averages, so two respected methods can return different numbers for the same person. Treat both results as reference points rather than measured metabolic rates. The calculator handles the arithmetic locally in your browser and reports resting BMR only; it does not add an activity multiplier, weight-loss goal, or weight-gain goal.
The resting baseline your result represents
A BMR result answers a narrow question: how much energy the body is expected to use while remaining at complete rest. It supports vital jobs such as keeping the heart and lungs working, maintaining brain and kidney activity, regulating temperature, and carrying out cell repair. It does not include the extra energy used to walk, exercise, or perform ordinary tasks. For that reason, a BMR result should not be labeled your total daily calorie burn.
The calculator deliberately keeps that boundary clear. Unlike a full calorie calculator, it stops at resting energy and applies no activity factor or weight objective. This makes it useful for establishing a baseline before making broader calorie or weight plans. It also explains why rounding the primary answer to a whole calorie is a display choice, not a claim that the underlying population equation is exact.
Four inputs and their units
The prediction method needs only four inputs. Select your sex, then enter your age in years, weight in kilograms, and height in centimeters. Those are the calculator’s required formats; a measurement still expressed in pounds or inches is not the same input and should be converted first. You can use the Weight Converter and Length Converter to obtain kilograms and centimeters. Selecting the female option applies the women-specific constant rather than the men-specific offset.
The table below preserves the exact coefficients used by the tool. The Mifflin–St Jeor row supplies the primary calculation. The revised Harris–Benedict row supplies the comparison; this tool uses the Roza and Shizgal revision rather than the original 1919 version.
| Equation | Calculation for women | Role in the calculator |
|---|---|---|
| Mifflin–St Jeor (1990) | 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161 | Primary result, rounded to the nearest whole calorie |
| Revised Harris–Benedict (Roza & Shizgal, 1984) | 447.593 + 9.247 × weight (kg) + 3.098 × height (cm) − 4.330 × age (years) | Side-by-side comparison for a resting-calorie range |
The units matter because every coefficient is tied to kilograms, centimeters, and years. The signs also show how each equation responds mathematically: with the other inputs fixed, the predicted value decreases as age increases and increases as weight or height increases. That is a property of the formulas, not proof that every person will respond identically. Convert each measurement before entering it and check that the value matches the unit stated beside the field.
Calculate your resting estimate
- Select your sex and enter your age, weight in kilograms, and height in centimeters. Check the unit beside every measurement before continuing.
- Read the Basal Metabolic Rate produced by the Mifflin–St Jeor equation. This is the primary result, rounded to the nearest whole calorie.
- Compare it with the revised Harris–Benedict estimate beside it. Use the two outputs to see a resting-calorie range rather than treating either equation as a personal measurement.
Nothing else is required for the resting calculation. Do not expect an activity level or weight goal to change the answer: this tool intentionally applies no activity multipliers or weight targets. The calculation runs locally in your browser, and the information you type is neither uploaded nor stored.
Hand-check example: For a 35-year-old woman weighing 65 kg and measuring 169 cm, the female Mifflin–St Jeor calculation is 10 × 65 + 6.25 × 169 − 5 × 35 − 161 = 650 + 1,056.25 − 175 − 161 = 1,370.25 kcal/day. Rounded to the nearest whole calorie, the primary result is 1,370 kcal/day. This illustrates the arithmetic only; it is not a personalized calorie recommendation.
How the two equations create a range
The two equations use the same four inputs but different coefficients. The primary method is the 1990 Mifflin–St Jeor equation. The calculator’s documented methodology identifies it as the equation most current clinical and dietetic guidance recommends for resting-energy prediction. The comparison uses the 1984 Roza and Shizgal revision of Harris–Benedict, not the 1919 original. For a typical adult, the revised Harris–Benedict result will usually be slightly higher because its overall constants and coefficients produce a higher prediction for many ordinary input combinations.
A higher second number is not a contradiction and does not reveal which equation is right for your body. Prediction equations describe average relationships rather than measuring your organs’ actual energy use. The side-by-side view makes model uncertainty concrete and discourages false precision. Use the Mifflin–St Jeor figure as the main reference because that is the tool’s designated primary method, but keep the Harris–Benedict figure in view when judging how much the model choice matters.
Do not treat the two outputs as strict personal minimum and maximum limits. They are two estimates calculated from the same characteristics, not measurements taken at the lowest and highest ends of your metabolism.
Reading the estimate within its limits
Direct laboratory measurement would require a metabolic cart. A four-input equation cannot account for every influence on metabolism. Body composition, thyroid function, genetics, and adaptation to dieting can all change an individual’s resting expenditure, yet none appears directly in either formula.
The calculator’s assumptions are equally important. Its results are estimates for a healthy adult, and it does not adjust for pregnancy, athletic body composition, illness, or medications. The documented methodology cautions that actual resting metabolism can differ from the estimate by roughly 10% or more. That limitation remains even when your measurements are precise and your age is entered exactly.
Use the output as a starting reference and compare real-world patterns over several weeks rather than assuming that a precise equation reveals your exact metabolism. Rounding to a whole calorie does not remove the underlying uncertainty. The number also cannot diagnose a metabolic condition or establish whether it is “normal” for you. For health, diet, or medical decisions, consult a qualified healthcare professional.
Moving from BMR to daily energy needs
Resting energy is only one part of a full daily estimate. Total Daily Energy Expenditure, or TDEE, adds movement, digestion, and other daily demands to the resting baseline. BMR alone should not automatically be treated as a maintenance intake or a weight-loss target.
Once you have reviewed the two resting estimates, use the calorie calculator when you need a TDEE-based daily figure with activity and goals included. The relationship between the measures is explained in How to Calculate BMR and TDEE Step by Step. This keeps the sequence clear: calculate the resting baseline with the BMR tool, compare the two equations, and add the broader daily context only when needed.
Do not apply a universal activity multiplier or promise that a fixed BMR-based deficit will produce a particular result. Individual response still varies, which is why the calculator provides general information rather than medical advice.