Free tool
Macro calculator
Work out how many calories and how much protein, carbs and fat to eat each day to lose weight, maintain or build muscle. It uses the same method as BiteSync's planner, built by a dietitian. Free, no sign-up, and nothing you enter is sent anywhere.
Fill in your details to see your daily calories, protein, carbs and fat.
How it's calculated
- Resting energy with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then +5 for men or −161 for women.
- Maintenance calories: resting energy × your activity level, from 1.2 for sedentary to 1.9 for extremely active.
- Your goal: 20% below maintenance to lose weight, or 10% above to build muscle. A percentage scales with you, unlike a flat 500 kcal.
- Proteinper kg of body weight, by activity and goal (table below). Above a BMI of 30 it's based on an adjusted weight.
- Carbs and fat share the remaining calories 5:3, with at least 0.6 g of fat per kg of body weight. Fibre is set at 30 g a day.
- Safety limits: never below 1,200 kcal a day for women or 1,500 for men, and no weight-loss target if your BMI is under 18.5.
| Activity | Maintain | Lose or build |
|---|---|---|
| SedentaryDesk job, little or no exercise | 1.0 g/kg | 1.2 g/kg |
| Lightly activeLight exercise 1-3 days/week | 1.1 g/kg | 1.2 g/kg |
| Moderately activeModerate exercise 3-5 days/week | 1.4 g/kg | 1.6 g/kg |
| Very activeHard exercise 6-7 days/week | 1.6 g/kg | 1.8 g/kg |
| Extremely activePhysical job + hard training daily | 1.8 g/kg | 2.0 g/kg |
Questions
How many calories should I eat to lose weight?
This calculator sets your target 20% below your maintenance calories, which works out at roughly 0.5–0.75 kg (1–1.5 lb) a week for most people. It never goes below 1,200 kcal a day for women or 1,500 for men, and it won't set a weight-loss target if your BMI is under 18.5.
How much protein do I need a day?
It depends on how active you are and on your goal. This calculator uses 1.0–2.0 g of protein per kg of body weight: towards the lower end if you're mostly sitting down, and the upper end if you train hard most days. Losing weight or building muscle moves you up within your activity level. Above a BMI of 30, protein is based on an adjusted weight so the target stays realistic.
What are maintenance calories?
The calories you use in a typical day, also called your TDEE. It's your resting energy use, estimated with the Mifflin-St Jeor equation, multiplied by your activity level. Eat about this much and your weight should stay roughly the same.
How accurate is a macro calculator?
It's an estimate. Mifflin-St Jeor is one of the most widely used equations, but people vary. Treat the result as a starting point: if your weight isn't moving as you expect after two or three weeks, adjust by a small amount, such as 100–200 kcal a day.
Is anything I enter saved?
Nothing you type is sent to BiteSync: the calculation runs in your browser. If you tap “Plan my week free”, your answers are kept in this browser for up to 7 days, so you don't have to type them again when you set up BiteSync.
Who shouldn't use this calculator?
It's for adults aged 16 and over. If you're pregnant or breastfeeding, have kidney disease or another medical condition, or have a history of an eating disorder, speak to your GP or a dietitian instead, because your needs are different.
How do I actually hit these numbers every day?
Plan ahead. BiteSync works out these same targets for you, plans your week's meals to hit them before you shop, and turns the week into one grocery list. It's free to start.
Targets are the easy part
Knowing your numbers doesn't tell you what to eat on Tuesday. BiteSync plans your week to these targets before you shop, gives you one grocery list, and checks your vitamins and minerals across the week.
Built by James, Dietitian. For general guidance only, not a substitute for advice from your GP or dietitian.