Protein Calculator Training
Enter your body weight, pick a goal, and get a protein target in grams per day — with the coefficient shown, the range it sits inside, the gram equivalent per pound, and how many calories and what share of your day it represents. The weight basis is always stated; it is never swapped silently.
Your details
The RDA — 0.8 g of protein per kg of body weight per day — is the number most people meet without trying, and the number most training advice quietly exceeds. It comes from the Institute of Medicine's 2005 DRI report and was designed as an adequate intake for general healthy adults: enough for the population to avoid deficiency, not a ceiling, and not calibrated for people who lift, run long distances, or diet hard. Treating the RDA as "the right amount for everyone" understates the evidence for exercisers exactly as much as treating 2.0 g/kg as mandatory overstates it.
For healthy exercising adults, the International Society of Sports Nutrition's 2017 position stand puts the practical range at 1.4–2.0 g/kg/day — sufficient to support muscle building and repair for most. Inside that range, Morton and colleagues' 2018 meta-analysis of resistance-training studies found the average benefit of adding protein tapers off around 1.6 g/kg/day, with the uncertainty interval reaching higher. We map goals to points inside the published range, and we keep the two claims separate on purpose: the ISSN paper supports the range; the Morton paper supports the plateau estimate; neither supports "more is always better," and this calculator won't tell you that.
Two boundaries we draw explicitly. First, the basis: this tool multiplies a coefficient by the body weight you enter — current weight by default. Lean-mass-based equations (the family commonly called Katch–McArdle, same form published by Cunningham in 1991) are a legitimate alternative when you have a trustworthy body-fat measurement, but we don't switch bases behind your back. Second, the population: if you have kidney disease, diabetes, a history of disordered eating, or any condition where protein intake is clinically managed, this general-adult tool is not your reference — a clinician is.
The goal selector maps to a coefficient: general adult → 0.8 g/kg (the IOM 2005 RDA); endurance training → 1.4 g/kg (the ISSN 2017 range's lower bound); strength and hypertrophy → 1.6 g/kg (the Morton 2018 group-average plateau); fat-loss retention focus → 2.0 g/kg (the ISSN range's upper bound, where the higher end is commonly used while dieting). Custom mode takes your number, displayed against the published bands so you can see where it falls.
Grams per day = coefficient × weight. From there the derived fields are pure arithmetic: grams per pound = grams ÷ 2.205; energy = grams × 4 kcal/g (the same American Atwater factor used across kcalcraft); energy share needs a calorie target, and if you didn't provide one, that field says "not computed" rather than inventing a number. RDA comparison divides your coefficient by 0.8 so the baseline context is one glance away.
The per-meal split is an even division across three meals (four on expand) — a practical convention for spacing protein through the day, not a proven optimum. Total daily intake is what the cited evidence actually speaks to; meal-timing refinements are a layer above what these papers establish, and we don't dress up a convention as a finding.
Every output is labeled with its basis: the coefficient's source (RDA, ISSN range bound, or Morton plateau estimate), and the weight basis you entered. If you train hard and your results diverge from the estimate for weeks, the calibration guide walks through reconciling the target with your own trend data instead of assuming the paper is right about you personally.
Frequently asked questions
Is 0.8 g/kg per day enough protein?
It is the RDA — an adequate intake for general healthy adults set in the IOM's 2005 DRI report — so for a sedentary person eating at maintenance, yes, it is a defensible baseline. It was not designed for people doing serious endurance or resistance training, which is why the ISSN's 2017 position stand frames 1.4–2.0 g/kg/day for healthy exercisers. "Enough" depends on what you ask your body to do; the RDA answers a narrower question than most fitness sites imply.
Can eating more protein harm healthy kidneys?
For healthy adults, protein intakes within the ranges used here have not been shown to harm kidney function in the evidence underlying these position stands, and the ISSN range is explicitly framed for healthy exercising populations. That framing matters: if you have existing kidney disease, diabetes, or any condition involving clinically managed protein intake, this calculator's population is not you — that decision belongs with your clinician, and no general-purpose tool should make it.
Should I base protein on current weight, target weight, or lean mass?
This calculator defaults to current weight and says so. During fat loss, anchoring to target weight is a legitimate coaching choice, which is why the form invites you to enter that weight explicitly. Lean-mass-based equations (commonly called Katch–McArdle; same form in Cunningham 1991) are a third option that genuinely needs a trustworthy body-fat measurement — plug one in casually and the error in lean mass swamps the elegance of the equation. What we won't do is switch the basis without telling you.
Does protein timing matter, or just the daily total?
The cited evidence speaks to daily totals: both the ISSN range and the Morton plateau are grams-per-day findings. Spreading protein across three or four meals is a sensible practical convention, and the calculator shows an even split for convenience — but present it as convention, not as a proven optimum. If your daily total is right and your meals are reasonably spaced, chasing a specific "anabolic window" protocol is a smaller variable than the total itself.
Is 2.0 g/kg an upper limit I shouldn't exceed?
It is the upper bound of the ISSN's 2017 range for healthy exercising adults, not a hard physiological cliff. Morton's 2018 analysis found the average marginal benefit of adding protein approaches zero around 1.6 g/kg, with an uncertainty interval extending to roughly 2.2 — so for most people most of the time, more than the range adds little. Values slightly above 2.0 are not automatically harmful for healthy adults, but if you feel you need substantially more than the range to make progress, the bottleneck is probably elsewhere: total energy, training stimulus, or sleep.
Does any of this apply if I eat mostly plant protein?
The published coefficients were not recalibrated for protein source in the papers cited here. Practically, many plant-forward eaters aim toward the upper part of the range to compensate for digestibility and amino-acid profiles of their staples — that is reasonable practical guidance, not a recalibrated coefficient from these sources, and we label it as such. If you want the full-day picture of how protein sits beside carbohydrate and fat, the macro calculator puts the pieces together.
References & sources
Supports: The 0.8 g/kg/day RDA used as the general-adult baseline coefficient.
Supports: The 1.4–2.0 g/kg/day range that bounds every training coefficient on this page.
Supports: The ~1.6 g/kg/day average plateau behind the strength/hypertrophy default.