Macro Calculator
Split a daily calorie target into protein, carbohydrate and fat in grams, using an evidence-based protein floor set by bodyweight rather than a flat percentage.
Macro Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: Macronutrient targets are set by first fixing protein from bodyweight — typically 1.6 to 2.2 g per kilogram — then allocating fat as a percentage of total calories, with carbohydrate taking the remainder. Protein and carbohydrate supply 4 calories per gram and fat supplies 9, so the three gram targets must reconcile exactly to the calorie total.
Formula
Atwater factors: protein and carbohydrate yield 4 kcal per gram, fat yields 9. Carbohydrate is solved last so the three components always reconcile exactly to the calorie target.
Worked Example
- Set protein from bodyweight. 1.8 g/kg × 82 kg = 147.6 g, which is 147.6 × 4 = 590 kcal.
- Set fat as a share of calories. 30% of 2,732 = 819.6 kcal, and 819.6 ÷ 9 = 91.1 g.
- Give carbohydrate the remainder. 2,732 − 590.4 − 819.6 = 1,322 kcal.
- Convert to grams. 1,322 ÷ 4 = 330.5 g of carbohydrate.
- Check the split. 22% protein, 48% carbohydrate, 30% fat — reconciling exactly to 2,732 kcal.
Practical note. Protein is fixed first deliberately. Percentage-based splits produce absurd protein targets at the extremes — 30% of 1,400 calories is only 105 g, too little for a heavier person in a deficit, which is exactly when protein matters most.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Preserving muscle in a calorie deficit
Protein requirements rise as calories fall, because the body becomes more willing to break down lean tissue for energy. Setting 2.2 g/kg or higher during an aggressive cut is well supported. Get the calorie target first from the TDEE Calculator.
Supporting hard training with adequate carbohydrate
Carbohydrate fuels high-intensity work, and cutting it too far usually shows up as flat, unproductive sessions before it shows up on the scale. Because carbohydrate is the balancing item here, lowering the fat share is the direct way to raise it — cross-check protein with the Protein Calculator.
Building a lean bulk that adds muscle rather than fat
A modest surplus with protein held at 1.8 to 2.2 g/kg gives the raw material for growth without excess fat gain. Track the outcome with the Lean Body Mass Calculator rather than the scale alone.
Methodology & Editorial Standards
Macronutrients are allocated in a fixed priority order — protein by bodyweight, then fat as a share of total energy, then carbohydrate as the balancing remainder — so the three targets always reconcile exactly to the calorie figure. Energy densities use the standard Atwater factors of 4, 4 and 9 kcal per gram. Protein bands reflect the current sports-nutrition consensus of roughly 1.6 to 2.2 g/kg for trained individuals, rising during energy restriction. Fat is constrained to a minimum of 15% of calories because sustained intake below that level risks impaired absorption of fat-soluble vitamins and hormonal disruption. The fibre target applies the 14 g per 1,000 kcal dietary reference. This engine implements the published formula exactly as specified in the source literature, with inputs validated for physiological plausibility before evaluation. Values outside the domain of the formula return an em-dash rather than a misleading figure.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Macro Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is the best macro split?
There is no single best split, but protein should be set from bodyweight rather than as a percentage. Beyond that, fat between 20 and 35% of calories suits most people, with carbohydrate filling the remainder and scaling with training volume.
Why set protein per kilogram instead of as a percentage?
Because percentage targets break down at the extremes. Thirty percent of a 1,400 calorie cut is 105 g, which is inadequate for a 90 kg person, while the same percentage of a 4,000 calorie bulk is far more than anyone needs. Bodyweight scaling avoids both failures.
How much protein do I actually need?
Sedentary adults need around 0.8 to 1.2 g/kg. Anyone training regularly benefits from 1.6 to 2.2 g/kg, and during an aggressive deficit up to 2.6 g/kg helps preserve lean mass. Intakes beyond that offer no further measurable benefit for most people.
Do macros matter more than total calories?
Calories determine whether you gain or lose weight; macros largely determine what that change is made of. Protein in particular decides how much of the weight lost comes from fat rather than muscle, so both matter for different reasons.
Can I eat fewer carbs and more fat?
Yes. Raise the fat percentage and carbohydrate falls automatically, since it is the balancing item. Provided protein and total calories hold, low-carbohydrate and higher-carbohydrate approaches produce very similar fat loss outcomes in controlled trials.
What is the minimum fat intake?
Around 15 to 20% of calories, or roughly 0.5 g per kilogram of bodyweight, whichever is higher. Dietary fat is required for absorbing vitamins A, D, E and K and for normal sex hormone production, so this engine will not go below 15%.
Do I need to hit my macros exactly?
No. Landing within about 5 to 10 g of each target daily is sufficient. Consistency across a week matters far more than precision on any single day, and obsessive tracking is a common route to giving up altogether.
Should macros change on rest days?
They can, though it is optional. Some people lower carbohydrate on rest days and raise it around training. Provided weekly totals are consistent, results are broadly similar, so choose whichever pattern you will actually sustain.
How do I track macros without weighing everything?
Weigh for two or three weeks to build a reliable sense of portion sizes, then move to estimation with occasional spot checks. Most of the accuracy comes from consistent protein sources and honest accounting of cooking oils.
Does fibre count towards carbohydrate?
In most food labelling, yes — fibre is included in total carbohydrate. Because it is largely indigestible, some people track net carbohydrate by subtracting it. The fibre target here is shown separately as a minimum to aim for.
Why is my carbohydrate target so high?
Because carbohydrate absorbs whatever calories protein and fat do not claim. If it looks too high, raise the fat percentage or the protein band, and the carbohydrate figure will fall correspondingly.
Are these targets suitable for a vegetarian diet?
The targets themselves are diet-agnostic. Hitting the protein figure without animal products requires more planning — legumes, soy, seitan and dairy or eggs where included — and often benefits from aiming at the upper end of the band, since plant proteins are generally less digestible.
Is this macro calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.
Which currency does it use?
Amounts display in US$ accounting format, but the underlying mathematics is currency-agnostic. The result is identical in any currency, so simply read the figures in your own.
Why does a result show an em-dash?
An em-dash indicates the calculation is not defined for the inputs given — typically a division by zero or a value outside the valid domain. We show a dash rather than a misleading number.
How do I report an error?
Email apexconverter.praxiscalc@gmail.com with the tool URL, your exact inputs, the output received and the output you expected. Verified mathematical errors are patched within 72 hours.