Protein Calculator
Calculate your daily protein requirement in grams from bodyweight and training status, with per-meal distribution and a lean-mass cross-check.
Protein 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: Protein requirements scale with bodyweight and activity. Sedentary adults need about 0.8 g per kilogram, recreational athletes 1.4 to 1.8 g/kg, and those in a calorie deficit up to 2.2 g/kg to preserve lean mass. Protein supplies 4 calories per gram.
Formula
The coefficient rises with training load and with the depth of any calorie deficit, since protein needs increase precisely when energy is restricted.
Worked Example
- Select the coefficient. Strength training calls for 1.8 g per kilogram.
- Multiply by bodyweight. 1.8 × 82 = 147.6 g per day.
- Convert to energy. 147.6 × 4 = 590 kcal from protein.
- Distribute across meals. 147.6 ÷ 4 = 36.9 g per meal, comfortably above the ~25 g leucine threshold.
- Cross-check against lean mass. At 20% body fat, lean mass is 65.6 kg, so this is 2.25 g per kg of lean tissue.
Practical note. Distribution matters as well as the total. Roughly 25 to 40 g of high-quality protein per meal maximally stimulates muscle protein synthesis, so four meals at 37 g is more effective than one meal at 148 g.
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 while dieting
Protein requirements rise as calories fall, because the body becomes more willing to catabolise lean tissue. Set the intake first, then build the rest of the diet around it with the Macro Calculator.
Supporting hypertrophy in a surplus
Muscle growth needs both a training stimulus and sufficient substrate. Around 1.6 to 2.2 g/kg covers essentially everyone; more offers no further benefit. Check the energy side with the TDEE Calculator.
Scaling intake to lean mass rather than total weight
For people carrying substantial fat, bodyweight scaling can overstate requirements. The lean-mass cross-check here handles that; derive lean mass precisely with the Lean Body Mass Calculator.
Methodology & Editorial Standards
Targets apply coefficients drawn from current sports-nutrition consensus: the 0.8 g/kg RDA represents the minimum to prevent deficiency in sedentary adults, not an optimum; 1.6 to 2.2 g/kg spans the range shown to maximise muscle protein synthesis and lean-mass retention in trained individuals; and up to 2.6 g/kg is supported during aggressive energy restriction. Energy is computed with the Atwater factor of 4 kcal per gram. Per-meal distribution is a simple even split, which approximates the per-meal leucine threshold of roughly 25 to 40 g of high-quality protein. Where body fat percentage is supplied, intake is also expressed per kilogram of lean mass. 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.
Protein Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How much protein do I need per day?
Sedentary adults need about 0.8 g per kilogram to avoid deficiency. Anyone training regularly benefits from 1.6 to 2.2 g/kg, and up to 2.6 g/kg during an aggressive deficit. For an 82 kg lifter that is roughly 148 g daily.
Is the 0.8 g/kg RDA enough?
It is the minimum to prevent deficiency in sedentary adults, not an optimum for body composition. Anyone training, dieting or over about 60 benefits from substantially more.
Can too much protein damage your kidneys?
There is no good evidence of harm in people with healthy kidneys, even at intakes well above 2 g/kg sustained for years. Those with existing kidney disease should follow clinical advice, as protein restriction may be indicated.
Should protein be based on total or lean bodyweight?
For most people total bodyweight is fine and simpler. For those carrying substantial fat, lean mass scaling avoids inflating the target, which is why the lean cross-check is shown here.
How much protein can the body absorb per meal?
Absorption is not the limiting factor — the body absorbs essentially all of it. What plateaus is the muscle protein synthesis response, around 25 to 40 g of high-quality protein per meal, which is why distribution across the day helps.
Does protein timing matter?
Far less than total daily intake. The old anabolic window has been substantially overstated; eating protein within a few hours either side of training is sufficient for essentially everyone.
Is plant protein as good as animal protein?
It can be, with attention to quantity and variety. Plant sources are generally lower in leucine and less digestible, so aiming for the upper end of the range and combining sources compensates well.
Does protein help with fat loss?
Yes, through several mechanisms: it is the most satiating macronutrient, has the highest thermic effect at 20 to 30% of its energy, and preserves lean mass during a deficit so more of the loss comes from fat.
How much protein is in common foods?
Roughly 31 g in 100 g of cooked chicken breast, 25 g in a can of tuna, 6 g per large egg, 20 g in 200 g of Greek yoghurt, and 25 g in a typical whey scoop.
Do older adults need more protein?
Yes. Anabolic resistance means older muscle responds less to the same protein dose, so 1.2 to 1.6 g/kg is commonly recommended after 65, alongside resistance training, to counter sarcopenia.
Is a protein supplement necessary?
No. It is a convenience, not a requirement. Whole foods meet the target perfectly well; powders simply make it easier when the number is high or schedules are tight.
Does protein need to be spread evenly?
Even distribution appears modestly better than skewing everything to dinner, which is the common pattern. Three to four meals each clearing the 25 g threshold is a reasonable structure.
Is this protein 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.