A calorie is a unit of energy. In nutrition, we use kilocalories (kcal). Your body burns calories from food to fuel all activities from breathing to exercise.

How many calories should I eat per day?

Adult women typically need 1,600–2,400 kcal/day and men need 2,000–3,000 kcal/day. Our calculator uses the Mifflin-St Jeor equation to personalise this estimate based on your age, weight, height, and activity level.

How do I lose weight by counting calories?

To lose approximately 0.5 kg (1 lb) per week, create a daily deficit of about 500 kcal below your TDEE. Combining a modest reduction in food intake with increased activity is more sustainable than extreme restriction.

TDEE (Total Daily Energy Expenditure) is the total calories you burn per day, combining your basal metabolic rate with all physical activity.

How accurate is the calorie calculator?

Calorie estimates are accurate within 10–15% for most people. Individual results vary based on genetics, body composition, and metabolism. Use the result as a starting point and adjust based on real-world results.

Calorie Calculator — Daily Calorie Needs

Gender

Age

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Weight

Height

Activity level

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Calories to maintain

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BMR (at rest)

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Lose weight (−500)

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Gain weight (+500)

About the Calorie Calculator

This calculator estimates your daily calorie needs using the Mifflin-St Jeor equation, widely regarded as the most accurate formula for most adults. It takes your age, weight, height, and sex into account to calculate your Basal Metabolic Rate (BMR), then multiplies it by an activity factor to give your Total Daily Energy Expenditure (TDEE).

What is BMR?

Basal Metabolic Rate is the number of calories your body burns at complete rest — the energy required just to keep your heart beating, lungs breathing, and cells functioning. It typically accounts for 60–75% of total daily calorie burn.

Activity levels explained

Sedentary — little or no exercise, desk job
Lightly active — light exercise 1–3 days per week
Moderately active — moderate exercise 3–5 days per week
Very active — hard exercise 6–7 days per week
Extra active — very hard exercise, physical job, or twice-daily training

Calorie goals

To lose weight, a daily deficit of 500 kcal below your TDEE typically produces around 0.5 kg (1 lb) of loss per week. To gain weight, a surplus of 500 kcal per day supports gradual muscle or weight gain. Avoid going below 1,200 kcal (women) or 1,500 kcal (men) without medical supervision.

Metric and imperial units

The calculator supports both metric (kg, cm) and imperial (lb, ft/in) inputs. Use the toggle at the top to switch — all values convert automatically.

Calories vs macronutrients

Total calorie intake determines whether you gain, maintain, or lose weight, but the source of those calories affects health, satiety, and performance. Protein requires the most energy to digest (20-30% of calories is used in digestion vs 5-10% for carbs and 0-3% for fat) and is the most satiating macronutrient per calorie. For weight management, getting adequate protein (1.6-2.2g/kg) is typically more important than the specific carb-to-fat ratio.

Protein — 4 kcal/g; essential for muscle retention during deficit; 1.6-2.2g/kg body weight recommended
Carbohydrates — 4 kcal/g; primary fuel for high-intensity exercise; glycogen storage is limited
Fat — 9 kcal/g; essential for hormone production and fat-soluble vitamin absorption; do not drop below 0.5g/kg
Alcohol — 7 kcal/g; provides energy but no nutritional value; not counted in standard macro tracking

Adjusting calories as you lose or gain weight

As your weight changes, your calorie requirements change too. A lighter body has a lower BMR and TDEE. When losing weight, recalculate your calorie target every 4-6 weeks or every 5kg of weight change. This prevents the common plateau where initial progress stalls because you are now eating at maintenance for your lighter body rather than at a deficit.

Diet breaks — deliberately eating at maintenance for 1-2 weeks every 4-6 weeks of deficit reduces hormonal adaptation
Reverse dieting — gradually increasing calories after a cut helps restore metabolic rate before a bulk
NEAT adaptation — non-exercise activity (fidgeting, walking) decreases during a deficit; factor this into adjustments
Tracking accuracy — studies show people underreport food intake by 20-40%; precision matters when calories are tight

Frequently Asked Questions

How are daily calories calculated?

We use the Mifflin-St Jeor equation, considered the most accurate for most people. BMR is calculated from your age, weight, height, and gender, then multiplied by an activity factor.

What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — just to keep you alive. It accounts for breathing, circulation, and cell production.

How many calories should I eat to lose weight?

A deficit of 500 calories per day typically results in about 0.5 kg (1 lb) of weight loss per week. Avoid going below 1,200 calories (women) or 1,500 calories (men) without medical supervision.

Is the calorie calculator accurate?

The Mifflin-St Jeor formula provides a good estimate for most people, but individual metabolism varies. Use the result as a starting point and adjust based on real-world results over 2–3 weeks.

How accurate are calorie counts on food labels?

UK regulations allow a 20% margin of error on calorie labels. Restaurant and takeaway calories are often estimated from recipes and can vary 30-50% from actual values depending on portion size and preparation. Tracking calories is still useful as a guide but precision matters less than consistency: use the same measurement method throughout.