Calorie and macro calculator
Estimate how many calories you burn in a day, get a gentle target for your goal, a starting split of protein, fat and carbs, and your daily sugar limit.
Your numbers
Fill in your age, height and weight to see your numbers.
A starting split of protein, fat and carbs
Protein for people who exercise is often put at 1.4–2.0 g per kg of body weight, which for you is a day. If you carry a lot of body fat, aim toward the lower end. The chart shows a simple middle-of-the-road split, not a rule.
Your daily sugar limit
Each square is one teaspoon (about 4 g). Filled squares show the 5% level, outlines the 10% limit. Free sugars mean sugar added to food and drinks plus sugars in honey, syrups and fruit juice. They do not include sugar in whole fruit or milk.
These are estimates, not medical advice. Your real needs depend on your body, health and habits. Check your weight and energy over 2–3 weeks and adjust by 100 kcal at a time.
How the numbers are worked out
- Resting energy (BMR). We use the Mifflin-St Jeor equation, published in 1990 from measurements on 498 healthy adults. For men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women the last number is −161 instead of +5.
- Maintenance. BMR is multiplied by an activity factor: 1.2 (mostly sitting), 1.375 (lightly active), 1.55 (moderately active), 1.725 (very active) or 1.9 (extremely active). These factors are the commonly used rules of thumb, not exact measurements.
- Your goal. To lose weight slowly we subtract 15% of maintenance, never more than 500 kcal, and never go below 1,200 kcal (women) or 1,500 kcal (men). To build muscle slowly we add 10%, never more than 300 kcal. Maintain keeps the number as is.
- Protein, fat, carbs. Protein follows the 1.4–2.0 g per kg range from the International Society of Sports Nutrition. Fat is set at about 28% of calories, and carbohydrate fills the rest. It is one sensible starting point among many.
- Sugar. The WHO recommends keeping free sugars below 10% of total energy, and says below 5% would bring additional health benefits. We turn that into grams using 4 kcal per gram.
A 30-year-old woman, 165 cm, 65 kg, lightly active. BMR = 10 × 65 + 6.25 × 165 − 5 × 30 − 161 ≈ 1,370 kcal. Maintenance = 1,370 × 1.375 ≈ 1,880 kcal. A gentle cut of 15% gives about 1,600 kcal, and 10% of that is 160 kcal, or 40 g of free sugars.
Who should not rely on this
- Anyone under 18. Growing bodies have different needs.
- Anyone who is pregnant or breastfeeding.
- People with diabetes, kidney disease, heart conditions or any condition that affects diet, or who take medication that changes appetite or metabolism. Ask your doctor first.
- Anyone who has or has had an eating disorder, or who finds counting calories stressful. Please work with a professional instead of using a target from a website.
Questions people ask
Why does another calculator give me a different number?
Different calculators use different equations and activity factors, so two honest tools can differ by a few hundred calories. Treat the result as a starting point and adjust from real life.
Should I eat back the calories I burn in workouts?
No. The activity level you choose already includes your exercise. Adding workout calories on top usually double counts.
How fast will I lose weight?
The NHS advises aiming for 0.5 to 1 kg a week. Our cut is deliberately gentler than that, usually 0.2 to 0.5 kg a week, because it is easier to stick to. The real result varies a lot from person to person.
Why is there a minimum of 1,200 or 1,500 kcal?
It is our own cautious limit, not an official rule. The NHS notes that very low calorie diets are not suitable or safe for everyone, so we keep targets well above that range and send you to a professional for anything lower.
Why is the sugar limit based on calories?
That is how the WHO states it. Someone who eats more energy has a higher limit in grams. For comparison, the NHS gives adults a fixed maximum of 30 g of free sugars a day, and the American Heart Association suggests about 25 g for women and 36 g for men.
Sources
- A new predictive equation for resting energy expenditure in healthy individuals. Mifflin and colleagues, American Journal of Clinical Nutrition, 1990.
- Understanding calories. NHS (UK).
- Obesity: treatment. NHS (UK).
- International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 2017.
- WHO calls on countries to reduce sugars intake among adults and children. World Health Organization, 4 March 2015.
- How does sugar in our diet affect our health?. NHS (UK).
- Added sugars. American Heart Association.
Sources last checked in October 2026. Official guidance changes, so check the original pages for the latest figures.
GymStarterGuide shares general information and is not medical advice. See our disclaimer.