Calculate exactly how many calories you need per day for weight loss, maintenance, or muscle gain. Free and accurate.
To manage your weight effectively, you need to understand how many calories your body actually needs. Two key numbers help with this: TDEE and BMR.
TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day. It includes everything: your resting metabolism, physical activity, digestion, and even fidgeting. This is the magic number for weight management:
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest - just to keep you alive. This includes breathing, blood circulation, cell production, and brain function. BMR typically accounts for 60-75% of your total daily calorie burn.
Important: You should never eat below your BMR for extended periods. Doing so can lead to nutrient deficiencies, muscle loss, metabolic slowdown, and other health issues.
Men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5
Women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161
TDEE = BMR x Activity Multiplier (1.2 to 1.9)
A calorie deficit of 500 calories per day typically results in losing about 0.5kg (1lb) per week - this is considered a healthy, sustainable rate. Going too aggressive (over 750 calorie deficit) can lead to muscle loss, fatigue, and is harder to maintain long-term.
For best results, combine a moderate calorie deficit with adequate protein intake (1.6-2.2g per kg of body weight) and resistance training to preserve muscle mass while losing fat.
Most people overestimate their activity level. If in doubt, choose one level lower than you think and adjust based on real-world results.
This calculator uses the Mifflin-St Jeor equation, which research shows is the most accurate formula for estimating metabolic rate for most people. However, all calculators provide estimates - your actual TDEE can vary based on genetics, muscle mass, hormones, and metabolic adaptations. Use the result as a starting point and adjust based on your real-world results over 2-3 weeks.
Several factors could be at play: 1) You may be underestimating how much you're eating - try weighing food for more accuracy. 2) Water retention can mask fat loss for days or weeks. 3) Your TDEE may be lower than calculated - try reducing by another 100-200 calories. 4) Weekend eating may be undoing weekday progress. Give it 3-4 weeks of consistent tracking before adjusting.
Exercise calorie estimates from fitness trackers are often 30-50% too high. If you're trying to lose weight, it's generally better to not eat back exercise calories, or at most eat back half. The activity multiplier in this calculator already accounts for regular exercise, so additional "eating back" can slow progress.
Eating below your BMR for extended periods is not recommended. It can lead to nutrient deficiencies, muscle loss, hormonal disruption, and metabolic slowdown. Very low-calorie diets (under 1,200 for women, 1,500 for men) should only be followed under medical supervision. A moderate deficit from your TDEE is more sustainable and effective long-term.
Now you know your calorie target, use NutraSafe to track your daily intake. Free calorie counter with thousands of UK foods and barcode scanning.
Download NutraSafe FreeLast updated: February 2026