Calorie Calculator

What Is a Calorie Calculator?

Calorie counting has a complicated reputation, but the underlying principle — energy balance — is hard to argue with. Consume more than your body uses and weight increases; consume less and it falls. The challenge is that most people have no idea how many calories their body actually needs each day, so they're guessing rather than planning.

The Harris-Benedict equation (revised 1990) is the standard formula used by NHS weight management programmes, sports nutritionists, and most fitness apps. It calculates your Basal Metabolic Rate — the calories you'd burn doing absolutely nothing — then multiplies by an activity factor. A sedentary woman in her thirties might need around 1,800–1,900 kcal a day. An active man in his twenties might need 2,800–3,200. That variation is large enough that generic advice like 'eat 2,000 calories' rarely applies to any specific person.

Enter your age, sex, height, weight, and activity level. You'll get your daily maintenance figure plus targets for a 0.5kg per week loss (a 500 kcal daily deficit) and modest gain. Use it as a starting point — track your actual intake against it for two weeks and adjust based on how your weight responds.

How Do You Use This Calorie Calculator?

Enter your age, gender, height (cm), weight (kg), and activity level. Click Calculate to see your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE).

1. Enter your age in years in the age field.
2. Select your sex from the dropdown menu.
3. Enter your height in centimetres.
4. Enter your weight in kilograms.
5. Choose your activity level from the five options provided.
6. Click Calculate to see your BMR and TDEE.
7. Review the maintenance, weight-loss, and weight-gain calorie targets.

How Does the Calorie Calculator Formula Work?

The formula used: Mifflin-St Jeor: BMR (men) = 10W + 6.25H - 5A + 5. BMR (women) = 10W + 6.25H - 5A - 161. TDEE = BMR × Activity Factor

What Are Some Example Calculations?

A 30-year-old male, 180 cm, 80 kg, moderately active: BMR = 1,780 kcal. TDEE = 2,759 kcal. To lose 0.5 kg/week, eat approximately 2,259 kcal/day.

When Should You Use a Calorie Calculator?

When starting a diet or fitness programme. Knowing your maintenance figure means you can set a deficit that's sustainable. Most nutritionists recommend no more than 500–750 kcal below maintenance for steady fat loss without significant muscle loss. Larger deficits tend to stall faster and cause more muscle wasting than fat loss, which is counterproductive if body composition matters to you.

When your progress has plateaued. Maintenance calories fall as you lose weight — a lighter body requires less energy. If you've been in a consistent deficit for 8–10 weeks and weight loss has stopped, recalculate your maintenance at your current weight. You may need to reduce intake by a further 150–200 kcal or increase activity to restore the same deficit.

What Do These Terms Mean?

How Do the Options Compare?

What Are the Best Tips to Know?

• Weigh food with a digital kitchen scale for the first two weeks to calibrate portion-size awareness.
• Track calories for at least 7 consecutive days to capture weekday and weekend variation.
• Reduce by 500 kcal/day for 0.5 kg/week fat loss — avoid deficits larger than 1,000 kcal.
• Recalculate TDEE after every 5 kg change in body weight.
• Prioritise protein at 1.6–2.2 g per kg of body weight to preserve muscle during a deficit.

What Mistakes Should You Avoid?

• Selecting a higher activity level than actual daily movement, which inflates TDEE by 300–600 kcal.
• Forgetting to count liquid calories from coffee, juice, alcohol, and protein shakes.
• Using the same TDEE for months without recalculating after significant weight change.
• Setting a calorie target below 1,200 kcal (women) or 1,500 kcal (men) without medical supervision.
• Ignoring the difference between gross exercise calories and net additional burn.