Calorie & Macro Calculator

How does this calorie calculator work?

The calculator runs in three steps, using your weight in kilograms, height in centimetres and age in years.

• Step 1, BMR (calories your body burns at rest). Men: 10 × weight + 6.25 × height - 5 × age + 5. Women: 10 × weight + 6.25 × height - 5 × age - 161.
• Step 2, TDEE (calories you burn on a normal day). BMR × your activity factor.
• Step 3, daily target. TDEE adjusted for your goal: minus 18% to lose weight, no change to maintain, plus 12% to build muscle.

These are the same numbers the tool shows in the BMR, TDEE and Daily target boxes, rounded to whole calories.

Which activity level should I choose?

Pick the level that matches a typical week, not your best week. The calculator uses these multipliers:

• Sedentary (little exercise): 1.2
• Light (1-3 days of exercise a week): 1.375
• Moderate (3-5 days a week): 1.55
• Active (6-7 days a week): 1.725
• Very active or athlete: 1.9

If you are unsure between two levels, choose the lower one. Most people overestimate how active they are, and it is easier to add food later than to explain a stalled result.

How many calories should I eat to lose weight?

For weight loss the calculator sets your target 18% below your TDEE. That is a moderate deficit that most people can keep up without feeling starved.

There is also a safety floor: a weight-loss target is never set below 1,200 kcal a day for women or 1,500 kcal a day for men. If 18% below your TDEE would land under that line, the target is raised to the floor. Eating less than this without medical supervision makes it hard to get enough protein, vitamins and minerals.

For muscle gain the target is 12% above TDEE, a small surplus that supports training without adding much extra fat. For maintenance the target equals your TDEE.

How are protein, carbs and fat calculated?

The daily target is split into macronutrients by percentage of calories, then converted to grams. Protein and carbohydrates provide 4 kcal per gram and fat provides 9 kcal per gram.

• Lose weight: 40% protein, 30% carbs, 30% fat
• Maintain: 30% protein, 40% carbs, 30% fat
• Build muscle: 30% protein, 45% carbs, 25% fat

The weight-loss split is higher in protein because protein helps you feel full and protects muscle while you eat less. Treat the gram numbers as a starting point, not a strict rule.

How much water does it suggest?

The water tip is 0.033 litres per kilogram of body weight, rounded to one decimal place, with a minimum of 2 litres a day. A 70 kg person sees about 2.3 litres. You need more in hot weather and when you sweat a lot.

How accurate is the result?

Any equation is an estimate of the average person with your measurements. Your real needs can be a few hundred calories higher or lower because of muscle mass, genetics, sleep and daily movement outside exercise.

The practical test is your weight trend. Eat close to your target for 2 to 3 weeks, weigh yourself under the same conditions a few times a week, and adjust by 100 to 200 kcal if the trend is not moving the way you want. For a forecast of how weight changes over months, the NIH Body Weight Planner models this in more detail.

Who should get personal advice first?

This calculator is general wellness information for healthy adults. Talk to a doctor or registered dietitian before following a calorie target if you are pregnant or breastfeeding, under 18, have a medical condition such as diabetes, kidney or heart disease, take medication that affects appetite or weight, or have a history of an eating disorder.