How to use the macro calculator
- Enter your body details and activity level – the calculator works out your daily calories from them.
- Choose a goal (lose, keep or gain weight) and a diet style.
- Pick how many meals you eat, to see the amount per meal.
- Press Calculate for grams of protein, carbs and fat a day, a chart of where your calories come from, and amounts per meal.
How macros are calculated
Your calorie target comes from the Mifflin-St Jeor BMR times your activity factor, plus or minus the change for your goal – the same method as the calorie calculator. Each diet style then splits those calories into the three macronutrients, and each split is turned into grams:
- Protein: 4 kcal per gram
- Carbohydrate: 4 kcal per gram
- Fat: 9 kcal per gram
\text{grams} = \dfrac{\text{daily kcal} \times \text{share}}{\text{kcal per gram}}- Protein:
2000 \times 0.25 \div 4 = 125g - Carbs:
2000 \times 0.50 \div 4 = 250g - Fat:
2000 \times 0.25 \div 9 = 56g
Diet styles compared at 2,000 kcal
| Diet | Protein | Carbs | Fat | Suits |
|---|---|---|---|---|
| Balanced (25/50/25) | 125 g | 250 g | 56 g | most people; fits the US and WHO guidelines |
| High protein (35/40/25) | 175 g | 200 g | 56 g | fat loss while keeping muscle, strength training |
| Low carb (30/25/45) | 150 g | 125 g | 100 g | people who feel fuller with less starch and sugar |
| Low fat (25/55/20) | 125 g | 275 g | 44 g | endurance sport, or a preference for a low-fat diet |
Percentages are protein / carbs / fat as a share of calories.
Recommended ranges
The US National Academies set Acceptable Macronutrient Distribution Ranges for adults: protein 10–35%, carbohydrate 45–65% and fat 20–35% of calories. The balanced, high-protein and low-fat plans stay inside or at the edge of these ranges. The low-carb plan goes below the carbohydrate range on purpose; it is a reasonable choice for many people, but not one the general guidelines recommend.
Which split you choose matters less than eating about the right number of calories and enough protein. Pick the one you can keep up – the best diet for weight change is the one you stick with.
Tips for each macro
- Protein keeps you full and protects muscle while you lose weight. Spread it over your meals, roughly 20–40 g each. The protein calculator gives a target from your weight and goal.
- Carbohydrates fuel exercise. Most should come from whole grains, beans, fruit and vegetables, which also bring fibre – about 14 g per 1,000 kcal.
- Fat is needed for hormones and to absorb vitamins A, D, E and K. Prefer olive oil, nuts, seeds and fish to fried and processed foods.
Limits
These are starting points for healthy adults. People with diabetes, kidney disease or other medical conditions, and anyone pregnant or breastfeeding, should set macro targets with a doctor or registered dietitian.
Frequently asked questions
What are macros?
Macronutrients – protein, carbohydrate and fat – are the parts of food that provide calories: 4 kcal per gram of protein or carbohydrate and 9 kcal per gram of fat.
What is the best macro ratio for weight loss?
There is no single best ratio. A calorie deficit causes the weight loss; higher protein (around 30–35% of calories) helps you stay full and keep muscle while you lose.
How many grams of protein should I eat a day?
At least 0.8 g per kg of body weight for adults, and about 1.6–2.2 g per kg if you train for strength or muscle. The result shows your amount per kg.
Do I have to hit my macros exactly?
No. Staying within about 5–10 g of each target, and close to your calories over the week, works just as well.
What does IIFYM mean?
"If it fits your macros" – a flexible approach where any food is allowed as long as your daily protein, carbs and fat stay close to the targets.