Daily Macros Calculator (carbs / protein / fat)
Enter a daily calorie target (e.g. from your TDEE or a cut/bulk plan) and the percentage of total energy from carbs, protein and fat — you immediately see grams per day for each macro. Pick a preset like Balanced 50/20/30, Keto 5/25/70 or High-protein 35/40/25, or type any custom split that sums to 100 %. Add your body weight to also get per-kg figures (e.g. 2 g protein / kg) — handy for planning a bodybuilding, cutting or maintenance diet against published targets.
Please enter a valid number
Carbs
250 g
1,000 kcal · 50 %
4 kcal/g · primary energy source
Protein
100 g
400 kcal · 20 %
4 kcal/g · muscle maintenance & repair
Fat
67 g
600 kcal · 30 %
9 kcal/g · hormones & fat-soluble vitamins
Macro split (% of total kcal)
Splits use the Atwater factors (carbs 4, protein 4, fat 9 kcal/g) and ignore fibre, alcohol and individual medical history. For weight loss, muscle gain or diabetes, consult a registered dietitian or doctor.
Formula
Carbs kcal = total kcal × carbs % Protein kcal = total kcal × protein % Fat kcal = total kcal × fat % Carbs g = carbs kcal / 4 // Atwater Protein g = protein kcal / 4 Fat g = fat kcal / 9 (Required: carbs % + protein % + fat % = 100 %)
- · Per-gram energy uses the general Atwater factors: carbs 4 kcal, protein 4 kcal, fat 9 kcal. Alcohol (7 kcal/g) and dietary fibre are not split out — if you drink, deduct alcohol calories separately.
- · The US Institute of Medicine (IOM 2005) Acceptable Macronutrient Distribution Ranges (AMDR) are: carbs 45–65 %, protein 10–35 %, fat 20–35 %. Ketogenic diets sit well below this band (< 10 % carbs) and need time to adapt — they are not advisable long-term without supervision.
- · Protein in grams matters most for training: sedentary adults need ≈ 0.8 g/kg, regular exercisers 1.2–1.6 g/kg, and muscle-gain or cutting phases 1.6–2.2 g/kg (ISSN 2017 position stand). Enter your body weight and the per-kg figure appears automatically.
- · Preset splits map to mainstream diet schools: Balanced 50/20/30 (close to USDA MyPlate), Mediterranean 50/15/35 (PREDIMED trial), Zone 40/30/30 (Sears, The Zone, 1995), Keto 5/25/70 (therapeutic high-fat), High-protein / IIFYM 35/40/25 (bodybuilding), Low-carb 25/35/40 (Atkins maintenance).
- · Grams are rounded to the nearest integer for shopping practicality, so the three rows can drift a few kcal from the input. Food labels in Hong Kong, the EU and the US all use the same Atwater 4/4/9 convention as your real-world ground truth.
- · This tool only splits a chosen calorie target — it does not decide the total for you. Get your total from a BMR calculator multiplied by an activity factor (TDEE), then ±10–20 % depending on a bulk / cut goal.
- · Sources: FAO/WHO 2003 "Food energy — methods of analysis and conversion factors"; USDA FoodData Central; IOM (2005) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids; Jäger et al. (2017) ISSN protein position stand.
Frequently asked
Where do the 4 / 4 / 9 kcal/g numbers come from?
They are the Atwater general factors, derived in the late 19th century by US agricultural chemist Wilbur Olin Atwater. He burnt foods in a bomb calorimeter, then subtracted estimated digestive losses. FAO/WHO 2003 and USDA FoodData Central still use these numbers; individual proteins and fats vary slightly, but the 4/4/9 system is accurate enough for everyday diet planning — and Hong Kong, EU and US nutrition labels are built on the same convention.
How much protein should I eat per day?
The WHO/IOM Recommended Daily Allowance (RDA) is 0.8 g/kg of body weight — that's the floor to prevent deficiency, not an optimum. The International Society of Sports Nutrition (ISSN 2017) suggests 1.2–1.6 g/kg for regular exercisers and 1.6–2.2 g/kg for muscle gain or to preserve lean mass during a calorie deficit. A 70 kg lifter therefore targets roughly 130–150 g protein per day. Enter your weight above and the per-kg figure shows up automatically for easy comparison.
Is a keto 5 / 25 / 70 split safe long-term?
Ketogenic diets (very-low-carb, high-fat) have decades of clinical use for drug-resistant epilepsy, especially in children, and are also used by some adults for weight loss or glycaemic control. Long-term safety data are still limited: "keto flu", constipation and rising LDL cholesterol can occur, and people on insulin face hypoglycaemia risk. The Hong Kong Medical Association and the American Diabetes Association both advise against long-term keto without medical supervision. This calculator only does the maths — it does not recommend any particular diet.
Why don't the three rounded gram values sum back to exactly my calorie target?
Grams are rounded to the nearest integer so they're practical for shopping (you won't weigh out 66.667 g of fat). The kcal column is then re-derived from the rounded grams using 4 / 4 / 9. For example 2,000 kcal × 30 % ÷ 9 = 66.67 g fat → displayed 67 g → 67 × 9 = 603 kcal. The three rows can therefore drift a few kcal from the target; this is deliberate for usability. If you need exact kcal matching, use the unrounded grams (66.67) in the formula instead.
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