Macro Calculator
Work out your daily protein, carbohydrate and fat targets based on your calorie needs and goal.
Moving one slider automatically adjusts the other two so your split always totals 100%.
Calorie Calculation
Daily Macro Targets
Macro Calculator
Our Macro Calculator works out your daily protein, carbohydrate and fat targets based on your calorie needs and goal. It starts by estimating your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, applies an activity multiplier to estimate your maintenance calories (TDEE), then adjusts for your goal — losing weight, maintaining, or gaining weight — before splitting the result into grams of protein, carbs and fat using a macro split of your choice.
How Macros Are Calculated
The calculator follows four steps:
- Basal Metabolic Rate (BMR): calculated using the Mifflin-St Jeor equation, which estimates your energy expenditure at rest based on your sex, age, height and weight.
- Total Daily Energy Expenditure (TDEE): your BMR multiplied by an activity factor to account for exercise and daily movement.
- Calorie target: your TDEE adjusted up or down depending on whether your goal is to lose, maintain or gain weight.
- Macro split: your calorie target divided into protein, carbohydrate and fat grams using your chosen percentage split (protein and carbs provide 4 kcal per gram, fat provides 9 kcal per gram).
Understanding Your Activity Level
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise, desk job |
| Lightly active | 1.375 | Light exercise 1-3 days a week |
| Moderately active | 1.55 | Moderate exercise 3-5 days a week |
| Very active | 1.725 | Hard exercise 6-7 days a week |
| Extremely active | 1.9 | Physical job, or training twice a day |
Common Macro Split Approaches
There is no single “correct” macro split — the right ratio depends on your goals, preferences and how your body responds, and what works well for one person may not suit another. Our calculator offers a few illustrative starting points you can adjust freely:
- Balanced (30/40/30): a moderate split some people use as a general starting point, spreading calories fairly evenly across the three macronutrients.
- High Protein (40/30/30): a higher-protein option some people try during a calorie deficit, though needs vary by individual and activity level.
- Low Carb (40/20/40): a lower-carbohydrate option with relatively more protein and fat; whether this suits you depends on your preferences and how you respond to it.
- High Carb (20/55/25): a higher-carbohydrate option sometimes used by endurance athletes who want more glycogen available for training, though this won’t be the right fit for everyone.
- Keto-style (25/5/70): a very-low-carbohydrate, high-fat starting split loosely modelled on ketogenic approaches. It represents a significant dietary change, isn’t suitable for everyone, and is best discussed with a healthcare professional before you try it.
You can also drag the sliders to build a fully custom split — the other two percentages adjust automatically so your total always adds up to 100%.
How Much Protein Do You Need?
Protein needs vary by activity level and goal. For people who exercise regularly, protein intakes around 1.6 to 2.2 grams per kilogram of bodyweight are commonly used, particularly when trying to build or preserve muscle. Individual needs vary depending on factors such as activity, goals and overall diet. The calculator shows your protein target in grams per kilogram of bodyweight so you can see where it falls.
Frequently Asked Questions
What is a macro calculator?
A macro calculator estimates how many grams of protein, carbohydrate and fat you should eat each day to meet a calorie target based on your goal, whether that is losing weight, maintaining weight, or gaining weight.
What formula does this calculator use?
The calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate, then applies an activity multiplier to estimate maintenance calories, before adjusting for your stated goal and splitting the result into macros.
What macro split should I use?
It depends on your goals and preferences. A balanced 30/40/30 split can be used as a general starting point, while a higher-protein split may suit some people during a calorie deficit. There is no universally best split — many people adjust theirs over time based on their goals, results and preferences.
How accurate is a macro calculator?
Macro calculators provide an estimate based on population-level formulas. Individual metabolism, body composition and activity can all cause actual needs to differ. Use the result as a starting point and adjust based on real-world progress over several weeks.
How much protein do I need per day?
General guidance suggests many people benefit from around 1.6 to 2.2 grams of protein per kilogram of bodyweight, particularly during a calorie deficit or when trying to build muscle, while lower intakes are typically sufficient for sedentary maintenance. This calculator shows your protein target in grams per kilogram so you can compare it to your own goals.
Should I eat back the calories I burn from exercise?
Your activity level selection already accounts for your typical weekly exercise, so you generally do not need to add exercise calories separately. If your training varies significantly day to day, some people choose a slightly higher activity level or track calories more precisely on heavy training days.
Is this calculator suitable for everyone?
This calculator gives general estimates and is not a substitute for personalised medical or dietetic advice. It is not intended for pregnant or breastfeeding women, under-18s, or people with an eating disorder, diabetes, or another medical condition affecting diet, who should seek guidance from a doctor, GP or registered dietitian.