Carbs or fat — which to cut?

Largely personal preference. Both diets work for fat loss when calories match. Cut carbs if you're sluggish on low-fat; cut fat if you find low-carb makes you bonk during workouts.

Why no fibre or sugar targets?

Those are within the carb total. Aim for 25–35 g fibre/day and keep added sugar under ~10 % of total calories. Whole-food carb sources usually handle both automatically.

How many calories per gram in each macro?

Protein and carbohydrate provide 4 kcal per gram, fat provides 9 kcal, and alcohol — not tracked here — provides 7. Multiplying these by your gram targets is how the calculator turns macros into a daily kcal total.

Should I cycle macros across the week?

Carb cycling (higher carbs on training days, lower on rest days) is popular but evidence shows weekly average matters far more than day-to-day distribution. Beginners should stabilize daily targets first; experienced lifters can experiment with cycling.

Carbs or fat — which to cut?

Largely personal preference. Both diets work for fat loss when calories match. Cut carbs if you're sluggish on low-fat; cut fat if you find low-carb makes you bonk during workouts.

Why no fibre or sugar targets?

Those are within the carb total. Aim for 25–35 g fibre/day and keep added sugar under ~10 % of total calories. Whole-food carb sources usually handle both automatically.

How many calories per gram in each macro?

Protein and carbohydrate provide 4 kcal per gram, fat provides 9 kcal, and alcohol — not tracked here — provides 7. Multiplying these by your gram targets is how the calculator turns macros into a daily kcal total.

Should I cycle macros across the week?

Carb cycling (higher carbs on training days, lower on rest days) is popular but evidence shows weekly average matters far more than day-to-day distribution. Beginners should stabilize daily targets first; experienced lifters can experiment with cycling.

Macro Calculator

Daily protein/carbs/fat in grams + kcal split, tuned to your goal (cut / maintain / bulk). Includes diet presets — balanced, high-protein, low-carb, keto, Mediterranean, Zone — or custom fat-percentage.

Result

Daily calorie target

2,400 kcal

Energy balance — weight stable

Diet presetAMDR mid-range (US IOM 2002). Carbs 45-65%, protein 10-35%, fat 20-35%.Balanced
Protein20 % of kcal · 1.60 g/kg bodyweight120 g
Carbs52 % of kcal · fuels training312 g
Fat28 % of kcal · hormones + satiety75 g
Per meal (3 meals)40P · 104C · 25F g
Per meal (4 meals)30P · 78C · 19F g

Maintain— Calories matched to TDEE.

Your protein target

120 g (1.6 g/kg)

ISSN band (active adults)

Sports-nutrition consensus for muscle preservation in trained adults.

120 – 165 g (1.6–2.2 g/kg)

WHO/IOM RDA (sedentary)

Minimum to prevent deficiency — not a target for trainees.

60 g (0.8 g/kg)

Atwater factors

Used to convert grams ↔ calories.

P 4 · C 4 · F 9 kcal/g

Source: ISSN Position Stand on Diet & Body Composition (Aragon et al., J Int Soc Sports Nutr 14:16, 2017); USDA/Atwater factors (Merrill & Watt, USDA Handbook 74, 1973).

Not medical advice — Macro splits are starting points. Kidney disease, diabetes, PCOS, and certain medications change what is appropriate. Active women should keep fat ≥ ~20% of calories to protect sex-hormone production. Work with a registered dietitian for clinical needs.

How to use this calculator

Use /health/calorie-calculator to find your TDEE first.
Pick a goal — cutting, maintaining, or bulking sets the calorie offset.
Default fat % is 28; raise it for low-carb diets, lower it if you train heavily.
Track for a week, then adjust based on actual weight change.

About this tool

Macros (protein, carbohydrate, fat) are the three energy-providing nutrients in your diet, and getting their split right is most of what makes a diet "work." Protein gets prioritised because it's the only macro your body can't store — eat too little and you lose muscle even in a calorie surplus. The default protein targets here (2.2 g/kg cutting, 1.6 g/kg maintaining) reflect current sports-nutrition consensus. Fat covers hormone production and satiety. Carbs fill the rest of your calorie budget and fuel training. The "per meal" breakdown helps you actually plan plates instead of obsessing over daily totals.

How it works — the formula

Protein g = weight(kg) × goal factor Fat g = (kcal × fat%) ÷ 9 Carbs g = (kcal − protein·4 − fat·9) ÷ 4

Atwater factors (Merrill & Watt 1973): protein and carbohydrate yield 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g. Protein is set first to preserve lean mass during a deficit (per ISSN guidelines), fat is set as a percentage of total calories (typically 25–30% for satiety and hormone health), and carbohydrate fills the remaining calorie budget.

Sources: USDA / Atwater factors — Merrill AL & Watt BK, Energy Value of Foods (USDA Handbook 74, 1973) · ISSN Diet & Body Composition Position Stand (Aragon et al., J Int Soc Sports Nutr 14:16, 2017) · IOM Acceptable Macronutrient Distribution Ranges — DRIs (2005)

Worked examples

Example 1

Cutting at 2,000 kcal target

Inputs:: weight = 70 kg, kcal = 2,000, protein = 2.2 g/kg, fat = 28%
Output:: 154 g P · 207 g C · 62 g F (616 + 826 + 558 = 2,000 kcal)

Example 2

Maintenance at 2,500 kcal

Inputs:: weight = 75 kg, kcal = 2,500, protein = 1.6 g/kg, fat = 30%
Output:: 120 g P · 318 g C · 83 g F (480 + 1,272 + 747 ≈ 2,500 kcal)

Example 3

Lean bulk at 3,000 kcal

Inputs:: weight = 80 kg, kcal = 3,000, protein = 1.8 g/kg, fat = 25%
Output:: 144 g P · 419 g C · 83 g F (576 + 1,676 + 747 ≈ 3,000 kcal)

Limitations

Atwater factors are population averages; real metabolizable energy varies by ±5–10% across foods (whole almonds, for example, deliver ~28% less than the label says).
Protein recommendations apply to healthy adults; people with kidney disease should not chase high-protein splits without medical input.
Fat below ~20% of calories can suppress sex hormone production in active women — keep a floor.
The split assumes no medical condition (e.g. PCOS, diabetes) that would benefit from carbohydrate-restricted patterns.

Macro splits are starting points. This calculator does not provide medical or dietetic advice — work with a registered dietitian if you have diabetes, kidney disease, or other conditions that affect macronutrient tolerance.

Frequently asked

For active people in a calorie deficit, 2.2 g/kg (1 g/lb) is what evidence says preserves the most muscle. Sedentary adults can do fine on 0.8 g/kg, but if you're reading a macro calculator you probably aren't sedentary.