BMR & Calorie Calculator
Enter your age, sex, weight, height, and activity level to estimate your BMR (calories burned at rest) and daily calorie needs. For general information only, not medical advice.
How to use the BMR & Calorie Calculator
Enter your age, sex, weight, and height, then select your activity level. Click "Calculate" to see your BMR (Basal Metabolic Rate — calories burned at complete rest) and your estimated daily calorie needs based on how active you are.
What is BMR?
BMR is the number of calories your body needs to maintain basic functions like breathing, circulation, and cell production while at complete rest. Your total daily calorie needs are higher than your BMR because they also account for physical activity, which is why this calculator applies an activity multiplier.
Frequently asked questions
What formula is used?
This calculator uses the Mifflin-St Jeor equation, a widely used and accurate formula for estimating BMR based on weight, height, age, and sex.
How should I use this for weight loss or gain?
To maintain your current weight, aim to eat around your calculated daily calorie needs. To lose weight, a modest calorie deficit is generally recommended; to gain weight, a modest surplus. Always consult a healthcare provider or nutritionist before making significant dietary changes.
Is this calculator a substitute for professional advice?
No. This tool provides a general estimate for informational purposes only. For personalized nutrition or health guidance, consult a doctor or registered dietitian.
Is my data stored anywhere?
No. This tool is part of the Toolyard collection of free, browser-based utilities. All calculations run locally in your browser — nothing you enter is uploaded to a server or stored anywhere.
How daily calorie needs are estimated
Calorie calculators typically start with your Basal Metabolic Rate (BMR) — the energy your body burns at complete rest just to keep organs functioning — and then multiply it by an activity factor based on how much you move in a typical day, from sedentary to very active. The result is your Total Daily Energy Expenditure (TDEE), a reasonable estimate of how many calories you'd need to maintain your current weight.
Using the number to set a goal
A commonly cited rule of thumb is that a deficit or surplus of roughly 3,500 calories corresponds to about one pound of body weight change, though individual results vary based on metabolism, water retention, and body composition. A moderate deficit of 500 calories a day targets roughly a pound a week of loss — aggressive deficits beyond that are harder to sustain and more likely to affect energy levels and muscle mass.
A note on accuracy
BMR formulas (like Mifflin-St Jeor or Harris-Benedict) are estimates based on population averages for age, sex, height, and weight — actual individual metabolism can vary by a meaningful margin either direction. Treat the result as a starting point to adjust from based on real-world progress, not an exact prescription, and consult a healthcare provider before making significant dietary changes.