Health & Wellbeing
Daily Calorie Needs (TDEE)
Estimated total daily calories to maintain weight.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
Total daily energy expenditure (TDEE) is the number of calories you use across a whole day: your resting metabolism plus the energy spent digesting food and moving about. This calculator estimates resting metabolism with the Mifflin-St Jeor equation and then multiplies it by an activity factor between 1.2 (sedentary) and 1.9 (extremely active). The result is a maintenance figure — roughly what you would eat to keep your weight stable.
Interpreting the result
Treat the number as a starting point, not a prescription. The activity multipliers are a long-standing convention rather than a measured quantity, and the gap between "lightly active" and "moderately active" is a judgement call that can shift the answer by several hundred calories. The reliable test is what actually happens: track your intake and weight over two to three weeks and adjust the figure to match reality. For weight loss, a deficit of roughly 500 kcal a day corresponds to a loss of about 0.5 kg a week, though the rate slows as weight falls.
Advice
To lose weight, eat below this figure; to gain, above it. A deficit of about 500 kcal/day gives roughly 0.5 kg loss per week. This is an estimate — individual needs vary.
Worked example
A 35-year-old woman, 68 kg and 165 cm, exercising three to five days a week: BMR = (10 x 68) + (6.25 x 165) - (5 x 35) - 161 = 680 + 1031.25 - 175 - 161 = 1375 kcal. Multiplied by 1.55 for moderate activity, TDEE is about 2130 kcal/day to maintain weight.
Pearls / pitfalls
- Most people overestimate their activity level. If the number does not match what the scales do over a few weeks, the activity factor is usually the culprit.
- Deliberate exercise is often a smaller share of daily expenditure than incidental movement — walking, standing, fidgeting and household activity.
- Very large deficits are counterproductive: they are hard to sustain, and they cost lean tissue as well as fat.
- The equation says nothing about diet quality. Two diets with identical calories can differ enormously in fibre, protein, micronutrients and how full they leave you.
Evidence & validation
The resting component uses Mifflin-St Jeor (1990). The activity multipliers derive from the physical activity level (PAL) approach used in national and international energy requirement frameworks, including the UK Scientific Advisory Committee on Nutrition's dietary reference values for energy, which express requirements as resting metabolic rate multiplied by a PAL value. The specific 1.2-1.9 ladder used here is a widely reproduced convention rather than a validated instrument.
Frequently asked questions
How many calories should I eat to lose weight?
A common starting point is about 500 kcal a day below your maintenance figure, which corresponds to roughly 0.5 kg a week. Adjust based on what actually happens over two to three weeks rather than trusting the calculated number.
Which activity level should I pick?
Choose based on your whole week, not your best week, and lean conservative. "Moderately active" means genuine exercise on three to five days, not an intention to start.
Do I add my exercise calories on top?
No — the activity multiplier already includes them. Adding a separate "calories burned" figure on top double-counts the same exercise.
Why has my weight stalled at these calories?
Energy needs fall as you lose weight, intake tends to drift upward without tracking, and daily movement often falls during a diet. Recalculate at your current weight and re-check portions.
Is this suitable during pregnancy?
No. Energy requirements in pregnancy and breastfeeding follow separate guidance — speak to your midwife, GP or a dietitian.
References
- 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.
- Scientific Advisory Committee on Nutrition. Dietary Reference Values for Energy. 2011.
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