Calorie Calculator — Daily Calorie Needs
Your basal metabolic rate and total daily energy expenditure from the Mifflin-St Jeor equation, the calorie target for the goal you pick, and the protein, fat and carbohydrate split that target implies.
Basal metabolic rate is what your body spends at complete rest, from the Mifflin-St Jeor equation — the one that validates best in the general population, and the reason this uses it rather than Harris-Benedict.
| Lose 1kg/week | 1,507.13 |
|---|---|
| Lose 0.5kg/week | 2,007.13 |
| Maintain | 2,507.13 |
| Lean gain | 2,757.13 |
| Muscle gain | 3,007.13 |
| Protein | 448 |
|---|---|
| Fat | 752.14 |
| Carbs | 1,306.99 |
How the calorie calculator works
Basal metabolic rate is what your body spends at complete rest, from the Mifflin-St Jeor equation — the one that validates best in the general population, and the reason this uses it rather than Harris-Benedict. If you enter a body fat percentage the Katch-McArdle equation is used instead, which works from lean mass and is more accurate for anyone lean or heavily muscled. Total daily energy expenditure multiplies BMR by an activity factor from 1.2 for sedentary to 1.9 for very active; most people overestimate this, and the honest answer for someone with a desk job who trains three times a week is moderate, not active. A deficit of 500 calories a day is about half a kilogram a week, because a kilogram of body fat is roughly 7,700 calories — that arithmetic is why the loss targets are what they are, and why a larger deficit is not proportionally better. The target is floored at 1,500 calories for men and 1,200 for women; below that it is hard to meet micronutrient needs from food. Protein is set from body weight rather than from calories, because the requirement tracks lean mass, and the remaining calories are split between fat at the share you choose and carbohydrate. These are estimates from population equations: measured expenditure varies by 10 to 15% between two people with identical inputs, so treat the number as a starting point and adjust on what the scale actually does over three weeks.
Formula: BMR (Mifflin-St Jeor) = 10w + 6.25h − 5a + 5 (male) or − 161 (female) · TDEE = BMR × activity · target = TDEE + goal adjustment
UK Calorie Planning Notes
Step 1: BMR (Basal Metabolic Rate)
BMR is the calories your body burns at complete rest — just to keep you alive (breathing, circulation, cell repair). This calculator uses the Mifflin-St Jeor equation (1990), which is the most accurate prediction formula for most adults:
- Male: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
- Female: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Step 2: TDEE (Total Daily Energy Expenditure)
TDEE = BMR × activity multiplier. The activity multiplier accounts for physical activity beyond baseline:
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, no exercise | ×1.2 |
| Lightly active | 1–3 days/week light exercise | ×1.375 |
| Moderately active | 3–5 days/week exercise | ×1.55 |
| Very active | 6–7 days/week hard training | ×1.725 |
| Extremely active | Physical job + daily exercise | ×1.9 |
Accuracy limitations
The Mifflin-St Jeor formula is accurate within ±10% for most people. Individual variation exists due to muscle mass, hormones, sleep, and genetics. For clinical accuracy, use indirect calorimetry (metabolic testing). The Advanced mode enables the Katch-McArdle formula, which is more accurate if you know your body fat percentage (uses lean body mass rather than total weight).
Calories for weight loss, maintenance, and gain Calorie targets by goal — weight loss, maintenance, muscle gainHow much of a deficit or surplus to eat for each goal — UK dietitian recommendations
Weight loss
A 500 calorie/day deficit produces approximately 0.5kg of fat loss per week — the standard clinical recommendation for sustainable loss. A 1,000 cal/day deficit aims for ~1kg/week but risks muscle loss, hunger, and metabolic adaptation if sustained beyond 8–12 weeks.
| Goal | Calorie adjustment | Weekly change | Notes |
|---|---|---|---|
| Lose 0.5kg/week | −500 cal/day | ~−0.5kg | Sustainable, preserves muscle |
| Lose 1.0kg/week | −1,000 cal/day | ~−1.0kg | Aggressive — high protein essential |
| Maintain weight | 0 | 0 | Eat at TDEE |
| Lean bulk | +250 cal/day | ~+0.1–0.2kg | Minimise fat gain while building muscle |
| Muscle gain | +500 cal/day | ~+0.25–0.5kg | Faster gain, some fat expected |
Minimum calorie thresholds
The UK Dietary Guidelines and dietitians recommend not going below 1,200 cal/day for women and 1,500 cal/day for men without medical supervision. Below these thresholds, it is difficult to meet micronutrient needs and muscle loss accelerates. Extreme restriction also triggers metabolic adaptation — the body reduces TDEE in response to severe deficit.
Diet breaks
If maintaining a large deficit for more than 8–12 weeks, consider a 1–2 week "diet break" at maintenance calories. Research shows this reduces metabolic adaptation and makes the overall diet more sustainable (Byrne et al., 2017 — CALERIE study).
How to set protein, fat, and carb targets for your calorie goal
Protein — the most important macro
Protein is essential for muscle preservation during a calorie deficit and muscle building during a surplus. Targets based on body weight:
| Goal | Protein target | Example (70kg person) |
|---|---|---|
| Weight loss (preserve muscle) | 1.6–2.2g per kg BW | 112–154g/day |
| Maintenance | 1.4–1.8g per kg BW | 98–126g/day |
| Muscle gain | 1.6–2.0g per kg BW | 112–140g/day |
| Sedentary (no exercise) | 0.8–1.2g per kg BW | 56–84g/day |
Fat — hormones and essential functions
Fat should make up 20–35% of total calories. Fat is essential for hormone production, fat-soluble vitamin absorption (A, D, E, K), and brain function. Going below 20% fat for extended periods can disrupt hormones — particularly in women.
Carbohydrates — energy and performance
After setting protein and fat, remaining calories come from carbohydrates. Carbs are not inherently fattening — excess calories cause fat gain, regardless of macronutrient source. Higher carb intake supports training performance; lower carb can reduce appetite for some people.
Calorie values per gram
- Protein: 4 cal/gram
- Carbohydrates: 4 cal/gram
- Fat: 9 cal/gram
- Alcohol: 7 cal/gram
UK Dietary Guidelines, obesity statistics, and where to get personalised advice
UK Dietary Guidelines
The UK Dietary Guidelines (NICE, 2013, updated 2024) recommend a dietary pattern based on vegetables, fruit, wholegrains, lean proteins, and dairy. The Guidelines use estimated energy requirements (EERs) based on age, sex, and activity level — aligned with the TDEE approach used in this calculator.
UK obesity context
According to NHS Digital (Health Survey for England), approximately 64% of UK adults are overweight or obese. Overweight is defined as BMI 25–30; obesity as BMI 30+. The most effective long-term interventions combine moderate calorie reduction, high protein intake, and regular physical activity — not extreme restriction.
Personalised advice
This calculator provides estimates — individual variation is significant. For personalised calorie and nutrition planning, consult a Registered Dietitian (HCPC-registered). Find one at: bda.uk.com/find-a-dietitian. NHS weight-management services are available via GP referral in most areas; some private health insurance also covers dietitian consultations.
Tracking tools used in the UK
Popular calorie-tracking apps used in the UK include MyFitnessPal (large UK food database), Cronometer (detailed micronutrient tracking), and Nutracheck (UK-developed with UK supermarket branded foods). Nutrition data in the UK is published by the Food Standards Agency (FSA) and Public Health England via the Composition of Foods Integrated Dataset (CoFID).
Frequently asked Frequently asked questions
How many calories do I need per day in the United Kingdom?
The average UK adults needs approximately 2,000–2,500 calories per day (women 1,800–2,200, men 2,200–2,800) at moderate activity levels. Your exact requirement depends on age, height, weight, sex, and activity level — this calculator computes it precisely using the Mifflin-St Jeor formula. The UK Dietary Guidelines base recommended intakes on estimated energy requirements (EERs) using the same underlying science.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to sustain basic life functions. TDEE (Total Daily Energy Expenditure) is your total daily burn including activity. TDEE = BMR × activity multiplier. Most people should eat at or near their TDEE to maintain weight, below it to lose, or above it to gain. TDEE is the more practically useful number.
How accurate is the Mifflin-St Jeor formula?
The Mifflin-St Jeor equation is accurate within approximately ±10% for most adults. It was validated in a 1990 study of 498 adults and is the formula most commonly recommended by dietitians and used in clinical settings. For greater accuracy, use the Katch-McArdle formula (requires body fat percentage) or undergo indirect calorimetry (metabolic testing). Actual TDEE can vary significantly based on muscle mass, hormonal status, sleep, and individual metabolism.
How many calories should I eat to lose weight safely in the United Kingdom?
A deficit of 500 cal/day below TDEE produces approximately 0.5kg fat loss per week — the standard recommendation from UK and international dietitians for sustainable, safe weight loss. Never go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision — below these thresholds, micronutrient needs cannot be met and muscle loss accelerates. For medically supervised very-low-calorie diets (VLCDs, under 800 cal/day), consult your GP.
Where these figures come from
Health thresholds and UK population statistics on this page are drawn from primary authorities — the National Health Service (NHS), the National Institute for Health and Care Excellence (NICE), and the World Health Organization (WHO).
- Adult BMI formula & categories — NHS — BMI healthy weight calculator.
- WHO adult BMI categories — WHO — Obesity and overweight fact sheet.
- UK overweight & obesity statistics — NHS Digital — Statistics on Obesity, Physical Activity and Diet.
- NICE weight-management guidance — NICE — Obesity guidance.
- NHS physical-activity guidelines — NHS — Physical activity guidelines for adults.
Last checked: April 2026. Rates and thresholds are reviewed against the source of record each November, when annual adjustments for the following tax year are published.
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Male · 30yr · 170cm · 70kg · Moderately active BMR: 1,695 cal · TDEE: 2,627 cal
A 30-year-old male, 170cm, 70kg, moderately active (3–5 days/week exercise). BMR (Mifflin-St Jeor): 1,695 cal/day. TDEE: 2,627 cal/day. To lose 0.5kg/week: eat 2,127 cal/day.
| BMR (base metabolic rate) | 1,695 cal/day |
|---|---|
| Activity multiplier | ×1.55 (moderate) |
| TDEE (daily burn) | 2,627 cal/day |
| Lose 0.5kg/week | 2,127 cal/day (−500) |
| Lose 1kg/week | 1,627 cal/day (−1,000) |
| Gain muscle (lean bulk) | 2,927 cal/day (+300) |
- Protein target (2g/kg BW) 140g protein/day
- Daily steps for 1 activity level up ~10,000 steps/day
- Estimated weekly loss at deficit ~0.5kg/week (sustainable)
- If sedentary (no exercise) TDEE drops to ~2,034 cal/day
- Body weight check Healthy BMI range: 63–80kg for 170cm
Female · 25yr · 165cm · 60kg · Lightly active BMR: 1,404 cal · TDEE: 1,930 cal
A 25-year-old female, 165cm, 60kg, lightly active (1–3 days/week exercise). BMR: 1,404 cal/day. TDEE: 1,930 cal/day. To lose 0.5kg/week: eat 1,430 cal/day. Minimum recommended: 1,200 cal/day.
| BMR (Mifflin-St Jeor) | 1,404 cal/day |
|---|---|
| Activity multiplier | ×1.375 (lightly active) |
| TDEE | 1,930 cal/day |
| Lose 0.5kg/week | 1,430 cal/day |
| Lose 1kg/week | 1,200 cal/day (minimum) |
| Maintain weight | 1,930 cal/day |
- Protein target (1.6g/kg BW) 96g protein/day
- At sedentary (office job, no gym) TDEE: ~1,681 cal/day
- Pregnancy: add ~300 cal/day (2nd trimester) ~2,230 cal/day
- Breastfeeding: add ~500 cal/day ~2,430 cal/day
- Minimum safe intake without medical supervision 1,200 cal/day
Calorie deficit for weight loss — 500 cal/day rule ~0.5kg/week · safe and sustainable
A 500-calorie daily deficit produces approximately 0.5kg of fat loss per week (3,500 cal = ~0.45kg fat). This is the standard clinical recommendation for sustainable weight loss — fast enough to see progress, slow enough to preserve muscle and avoid metabolic adaptation.
| Calorie deficit | −500 cal/day |
|---|---|
| Weekly loss | ~0.5kg/week |
| Monthly loss | ~2.0kg/month |
| −1,000 cal/day deficit | ~1.0kg/week (aggressive) |
| Minimum intake (women) | 1,200 cal/day — do not go below |
| Minimum intake (men) | 1,500 cal/day — do not go below |
- Rate of loss vs muscle loss Faster loss = more muscle lost
- Metabolic adaptation Metabolism slows ~10–15% after 6 weeks of deficit
- Diet break strategy 2-week maintenance break every 8–12 weeks
- Protein during deficit 1.6–2.2g/kg body weight to protect muscle
- Best approach 500 cal deficit + 150g+ protein + strength training
Mifflin-St Jeor formula — how BMR is calculated Most accurate equation for most people
The Mifflin-St Jeor equation (1990) is the gold standard for BMR estimation. It accounts for weight, height, age, and sex. It is more accurate than the older Harris-Benedict formula for most modern individuals.
| Male BMR formula | (10×weight) + (6.25×height) − (5×age) + 5 |
|---|---|
| Female BMR formula | (10×weight) + (6.25×height) − (5×age) − 161 |
| Accuracy vs indirect calorimetry | ±10% for most people |
| Activity multipliers | 1.2 (sedentary) to 1.9 (very active) |
| TDEE = BMR × | activity multiplier |
| Alternative: Katch-McArdle (uses lean mass) | More accurate if body fat % known |
- How to improve accuracy Use Katch-McArdle if you know body fat %
- Weight units Kilograms (metric) — convert: kg = lb ÷ 2.205
- Height units Centimetres — convert: cm = ft × 30.48
- Validation study Mifflin SJ et al., 1990, JADA — 498 subjects
- For medical use Use measured RMR via indirect calorimetry
Worked examples
| Inputs | TDEE — Total Daily Calories | Note |
|---|---|---|
| A 30-year-old man, 170cm, 70kg, moderately active | 2,507 cal | 1,618 BMR and 2,507 TDEE |
| The same person sedentary instead | 1,941 cal | activity is the largest single lever — 566 calories a day |
| Losing half a kilogram a week | 2,507 cal | a 500-calorie deficit against a 2,507 TDEE |
The sources behind this calculator
- Mifflin MD et al., "A new predictive equation for resting energy expenditure in healthy individuals", Am J Clin Nutr 1990 — the BMR equation used here
- World Health Organization — Waist circumference and waist–hip ratio (2008 expert consultation) — waist-to-hip cut-offs
- Tanaka H, Monahan KD, Seals DR, "Age-predicted maximal heart rate revisited", J Am Coll Cardiol 2001 — 208 − 0.7 × age
- Nathan DM et al., "Translating the A1C assay into estimated average glucose values" (ADAG), Diabetes Care 2008 — eAG = 28.7 × A1c − 46.7
- Mosteller RD, "Simplified calculation of body-surface area", N Engl J Med 1987 — BSA = √(height × weight / 3600)
- NHS — national health guidance
Last checked: September 2026. The equations are fixed by their published papers and do not change with tax years or regulations; the thresholds quoted in verdicts name the body that set them.