Calorie Calculator
Find out exactly how many calories you need each day. Calculate your BMR and TDEE, then get personalised targets for weight loss, maintenance or muscle gain using the trusted Mifflin-St Jeor formula.
Calculate Your Daily Calorie Needs
Enter your details below to get your maintenance calories and goal-based targets.
Understanding Your Daily Calorie Needs
A calorie is a unit of energy, and the number of calories you eat versus the number you burn determines whether you lose, maintain or gain weight. This calculator works out two key figures — your BMR and your TDEE — and then translates them into practical daily calorie targets for whatever goal you have in mind, whether that's losing fat, maintaining your current weight or building muscle.
What Is BMR (Basal Metabolic Rate)?
Your Basal Metabolic Rate is the number of calories your body burns at complete rest, simply to stay alive. It powers essential functions like breathing, circulating blood, regulating temperature and supporting brain activity. For most people, BMR accounts for 60–70% of total daily calorie expenditure, which is why it forms the foundation of any calorie calculation. Larger, younger and more muscular bodies generally have higher BMRs.
What Is TDEE (Total Daily Energy Expenditure)?
TDEE is the total number of calories you burn in a day once activity is included. It is calculated by multiplying your BMR by an activity factor that reflects how active you are — from 1.2 for sedentary lifestyles up to 1.9 for very physically demanding ones. Your TDEE is your maintenance calorie level: eat that many calories and your weight stays the same, eat fewer to lose weight, or eat more to gain.
The Mifflin-St Jeor Formula
This calculator uses the Mifflin-St Jeor equation, which research has shown to be one of the most accurate methods for estimating BMR in the general population:
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
The BMR is then multiplied by your activity factor to produce your TDEE.
Calories for Weight Loss
Losing weight requires a calorie deficit — eating fewer calories than you burn. Because roughly 7,700 calories equal one kilogram of body fat, a daily deficit of 500 calories produces about 0.5 kg of fat loss per week, a pace most experts consider safe and sustainable. A steeper 1,000-calorie deficit can yield around 1 kg per week but is harder to maintain and risks muscle loss. As a rule, avoid eating below your BMR for long periods.
Calories for Muscle Gain
Building muscle calls for a modest calorie surplus, usually 250–500 calories above your TDEE, paired with regular resistance training and sufficient protein (about 1.6–2.2 g per kilogram of body weight). A smaller surplus helps you add lean mass while limiting fat gain. Gaining weight slowly and steadily generally produces a better physique than aggressive "bulking".
Tips for Using Your Calorie Target
- Track for a few weeks: Use the calculated number as a starting point, then adjust based on how your weight actually changes.
- Prioritise protein: Adequate protein preserves muscle during weight loss and supports growth during a gain phase.
- Don't crash diet: Extreme deficits slow your metabolism and are hard to sustain.
- Stay consistent: Long-term habits matter far more than perfect daily numbers.
- Recalculate periodically: Your needs change as your weight and activity level change.
Note: This calculator provides estimates for healthy adults and is for informational purposes only. It is not medical or nutritional advice. Consult a doctor or registered dietitian before making significant changes to your diet, especially if you have a medical condition, are pregnant or are under 18.
Frequently Asked Questions — Calorie Calculator
BMR is the number of calories your body burns at complete rest just to keep you alive — powering your heart, lungs, brain and other vital functions. It typically accounts for 60–70% of the calories you burn each day. Knowing your BMR is the starting point for working out how many calories you need to maintain, lose or gain weight.
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day, including BMR plus all physical activity, exercise and digestion. It is calculated by multiplying your BMR by an activity factor. TDEE is your true "maintenance" calorie level — eat that amount and your weight stays stable; eat less to lose weight and more to gain.
This calculator uses the Mifflin-St Jeor equation, widely regarded as the most accurate formula for estimating BMR in healthy adults. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: the same formula but − 161 instead of + 5. The result is then multiplied by an activity factor to get TDEE.
To lose weight you need a calorie deficit. A safe, sustainable target is 500 calories below your TDEE per day, which produces roughly 0.5 kg of fat loss per week. A larger 1,000-calorie deficit yields about 1 kg per week but is harder to sustain. Avoid eating below your BMR for extended periods, as it can slow your metabolism and cause muscle loss.
To build muscle you need a modest calorie surplus — typically 250–500 calories above your TDEE per day — combined with resistance training and adequate protein (around 1.6–2.2 g per kg of body weight). A smaller surplus minimises fat gain while still supplying enough energy to build lean mass. Gaining slowly is usually better than a large bulk.
Calorie calculators provide a solid estimate, but individual metabolism varies due to genetics, body composition, hormones and other factors. Treat the number as a starting point: track your weight and intake for 2–3 weeks, then adjust up or down based on real results. The formula gives the target; your own data fine-tunes it.