Macro Calculator
Calculate your daily macronutrient targets (protein, carbs, fat) based on TDEE, goal, and preferred macro split. Supports weight loss, maintenance, and muscle gain.
Did this tool work for you?
How to use this calculator
BMR (Mifflin-St Jeor) × activity multiplier = TDEE. Goal adjusts calories (−500 for loss, +300 for gain). Macros are split from adjusted calories.
- 1
Enter your body weight, height, age, and sex.
- 2
Select your activity level — be honest; most people overestimate.
- 3
Choose your goal: lose, maintain, or gain.
- 4
The calculator gives calorie target and a balanced 30/40/30 macro split. Adjust ratios based on your preferences.
Frequently asked questions
How are the calories worked out?
The code uses the Mifflin-St Jeor equation for BMR: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then +5 for men or −161 for women. That BMR is multiplied by the activity factor you choose to give TDEE, and the goal adds −500, 0 or +300 kcal.
Are the macro percentages adjustable?
No. The split is fixed at 30% protein, 40% carbohydrate and 30% fat of the target calories, converted at 4, 4 and 9 kcal per gram. There is no slider, no grams-per-kilogram option and no keto or high-protein preset, so you would need to rework the grams yourself.
Is the protein amount sensible for my weight?
The protein figure is a percentage of calories, so it rises with your calorie target rather than with body weight. With the default 75 kg man it comes to 197 g, about 2.6 g per kg. For the 60 kg woman in a deficit it is 100 g, about 1.7 g per kg. Check the grams per kilogram against what a dietitian suggests.
Does it stop me choosing an unsafe calorie target?
No. There is no minimum calorie floor, so a small, sedentary person who chooses the −500 kcal goal can receive a very low figure. Treat the target as a starting estimate and ask a doctor or registered dietitian before eating at a large deficit.
What are the units, and can I enter pounds?
Weight must be in kilograms and height in centimetres; there is no unit switch. Age is in years. Weight, height or age that is zero, negative or not a number returns an error instead of a result.
Why is BMR sometimes close to TDEE?
The sedentary multiplier is 1.2, so TDEE is only 20% above BMR for that choice. The four higher options use 1.375, 1.55, 1.725 and 1.9. People often pick a higher level than their week really supports, which inflates every number that follows.
What does it not account for?
Body fat, muscle mass, pregnancy, breastfeeding, medical conditions, dietary restrictions, fibre, and sex other than the two options. Mifflin-St Jeor is a population estimate, and real needs can differ. This is general information, not medical or nutrition advice.
Macro calculator — from Mifflin-St Jeor to grams of protein, carbs and fat
Calories first, then grams
The calculator works in two stages. First it estimates the energy your body uses at rest with the Mifflin-St Jeor equation and multiplies by an activity factor to reach maintenance calories. Then it applies your goal, subtracting 500 kcal for weight loss or adding 300 kcal for muscle gain, and rounds the result to a daily target. In the second stage that target is carved into protein, carbohydrate and fat at 30%, 40% and 30%.
Inputs the code accepts
The table lists the multipliers and goal adjustments built into the tool.
| Setting | Value used |
|---|---|
| Sedentary | BMR × 1.2 |
| Light (1–3 workouts a week) | BMR × 1.375 |
| Moderate (3–5 workouts a week) | BMR × 1.55 |
| Active (6–7 workouts a week) | BMR × 1.725 |
| Very active | BMR × 1.9 |
| Lose weight | −500 kcal |
| Maintain | 0 kcal |
| Gain muscle | +300 kcal |
Worked examples
Each was run through the calculator. The defaults, a 75 kg, 175 cm, 30-year-old man at moderate activity, give a BMR of 1,699 kcal and a maintenance target of 2,633 kcal, split into 197 g protein, 263 g carbohydrate and 88 g fat. A 60 kg, 165 cm, 28-year-old woman at light activity has a BMR of 1,330 and a TDEE of 1,829; choosing weight loss lowers her target to 1,329 kcal with 100 g protein, 133 g carbohydrate and 44 g fat. An 82 kg, 180 cm, 25-year-old man at the active level has a BMR of 1,825 and a TDEE of 3,148; choosing muscle gain raises the target to 3,448 kcal with 259 g, 345 g and 115 g.
How the grams are derived
Protein and carbohydrate each provide four kilocalories per gram and fat provides nine, so the code divides 30% of the target by 4 for protein, 40% by 4 for carbohydrate and 30% by 9 for fat. That is why fat is the smallest number even though it takes the same share of calories as protein. Each figure is rounded to the nearest gram, so adding the grams back up can differ from the target by a few kilocalories.
Using the numbers sensibly
Treat the output as a first draft. Weigh yourself at similar times over a couple of weeks, compare the trend with the plan, and adjust. Because the percentages are fixed, anyone who wants a higher protein density or a lower-carbohydrate pattern will need to reshape the grams manually. Anyone with a medical condition, a history of disordered eating, or who is pregnant should get individual guidance, as this page is general information and not nutrition or medical advice.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →