TDEE Calculator: Daily Calorie Needs and Basal Metabolic Rate (BMR)
How many calories does your body need each day? This tool estimates your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, the most accurate of the common prediction equations for adults, then multiplies it by your activity level to give your total daily energy expenditure (TDEE), plus safe fat-loss and muscle-gain targets and a macro split.
Calculate your daily calories
Mifflin-St Jeor 1990Suggested macro split on your fat-loss calories
BMR vs TDEE: what is the difference?
Basal metabolic rate (BMR) is the energy your body needs at complete rest just to stay alive: heartbeat, breathing, brain, liver and kidney function, cell renewal and keeping your body warm. For most people who are not very active it is the largest part of daily energy use.
Total daily energy expenditure (TDEE) is everything you burn in 24 hours. It has three parts:
- Basal metabolic rate: the largest share.
- Thermic effect of food: about 10% of calories, the energy needed to digest and absorb food; it is higher for protein.
- Activity energy: exercise plus everyday non-exercise movement such as walking, standing and housework. This part varies most between people.
Eat about your TDEE and your weight stays roughly stable; eat less and you lose weight; eat more and you gain.
The Mifflin-St Jeor equation: how the calculator works
The Mifflin-St Jeor equation was published in 1990. A later systematic review for the American Dietetic Association found it was the equation most likely to predict resting metabolic rate within 10% of the measured value in both non-obese and obese adults:
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
Then: TDEE = BMR × activity factor.
Worked example: a 34-year-old woman who weighs 68 kg, is 165 cm tall and exercises 3–5 days a week. BMR = 680 + 1031.25 − 170 − 161 = 1,380 kcal, and TDEE = 1,380 × 1.55 = 2,139 kcal a day. For fat loss with a 20% deficit she needs about 1,712 kcal; for muscle gain with a 15% surplus about 2,460 kcal.
Activity factor chart
| Activity level | Description | Factor |
|---|---|---|
| Sedentary | Desk job, little walking, no regular exercise | 1.2 |
| Lightly active | Light exercise or brisk walking 1–3 days a week | 1.375 |
| Moderately active | Moderate exercise 3–5 days a week | 1.55 |
| Very active | Hard exercise 6–7 days a week | 1.725 |
| Extremely active | Professional athlete, training twice a day, or heavy physical work | 1.9 |
Tip: most people overestimate their activity. If in doubt, pick the lower level. The factor already includes your training, so do not add the calories your smartwatch shows on top of your TDEE.
How many calories to lose weight safely?
The calculator suggests a moderate 20% deficit below your TDEE and never goes below your BMR. That usually means losing about 0.5 to 1 kg a week at first, the pace most medical guidelines recommend to protect muscle mass.
The old rule that “7,700 calories = 1 kg of fat” is an oversimplification. Modelling from the US National Institutes of Health showed that weight loss slows over time because a lighter body burns less energy. Recalculate every time you lose 4–5 kg.
- Do not follow diets below 800 calories a day unless under direct medical supervision.
- People with diabetes on insulin or sulfonylureas can get low blood sugar when they eat less, so plan changes with your doctor.
- During pregnancy and breastfeeding, do not run a calorie deficit without medical guidance.
Macro split: protein, fat and carbohydrates
The calculator applies a practical split to your fat-loss calories:
- Protein 1.8 g per kg of body weight: a meta-analysis in the British Journal of Sports Medicine found that the benefit of protein for muscle gains with resistance training levels off around 1.6 g/kg, with a possible upper value near 2.2 g/kg. People with chronic kidney disease need lower amounts set by their doctor.
- Fat 25% of energy: within the 20–35% range of the European Food Safety Authority, favouring olive oil, nuts and oily fish.
- Carbohydrates the rest: from whole grains, legumes, vegetables and fruit, preferably low-GI choices for steadier blood sugar.
In the example above (1,712 kcal): about 122 g protein, 48 g fat and 199 g carbohydrate a day.
Limits of the calculation
All metabolic equations predict averages for groups; your real metabolism can be about 10% higher or lower. Accuracy drops in very muscular athletes, the very old, people with thyroid disorders and people taking medicines that affect metabolism. The equation is designed for adults; teenagers need extra energy for growth.
Foods that help you reach your goals
Protein and fibre sources from our food guide, with their calories and glycaemic index:
To check whether your current weight is in a healthy range, start with the BMI calculator, and track belly fat with the waist-to-height ratio calculator.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is what your body burns at complete rest; TDEE is your total daily burn once digestion, daily movement and exercise are added. Weight-loss plans are built on TDEE, not BMR.
How many calories should I eat to lose weight?
Subtract about 20% from your TDEE without going below your BMR. For a woman with a TDEE of 2,139 kcal, that is about 1,712 kcal a day.
Is the Mifflin-St Jeor equation accurate?
It is the most accurate of the common equations for adults according to a systematic review for the American Dietetic Association, but it is still an estimate that can be about 10% off your measured value. Track your weight for two weeks and adjust.
Why has my weight loss stalled even though I eat below my TDEE?
A lighter body burns less energy, and water retention can temporarily hide fat loss. Recalculate with your new weight, track your waist and check that your food tracking is accurate.
How much protein do I need per day?
The adult minimum is about 0.8 g per kg. During weight loss with resistance training, 1.6 to 2.2 g/kg helps protect muscle. People with kidney disease should follow their doctor’s advice.
Should I add the calories I burn exercising to my TDEE?
No. The activity factor already includes your usual training. Adding it again counts it twice and cancels your deficit.
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Scientific sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789.
- FAO/WHO/UNU. Human energy requirements. Report of a Joint FAO/WHO/UNU Expert Consultation. Rome: FAO; 2004.
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826-837.
- Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384.
- EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). Scientific Opinion on Dietary Reference Values for fats. EFSA Journal. 2010;8(3):1461.
This calculator is an educational estimate for healthy adults and does not replace a plan from a dietitian. If you have diabetes, kidney or heart disease, or are pregnant or breastfeeding, talk to your doctor before changing your calorie intake.