Protein calculator

How your protein target is calculated

Protein needs scale with body weight, not with total calories, so every serious recommendation is expressed in grams per kilogram of body weight. The calculator multiplies your weight by a range that depends on your goal, then gives you the midpoint as a single number to aim for.

The formula in words

Take your body weight in kilograms. Multiply it by a low and a high multiplier for your goal, for example 1.6 and 2.2 for building muscle. That gives a range in grams. The daily target shown is the midpoint of that range, rounded to a whole gram.

The formula with numbers

A 75 kg person building muscle: 75 × 1.6 = 120 g at the low end, 75 × 2.2 = 165 g at the high end. Midpoint: (120 + 165) ÷ 2 = 142.5, rounded to 143 g a day. The same person just maintaining health at the RDA of 0.8 g per kg would need 60 g a day, less than half as much.

Per meal target

The calculator also divides your total across the number of meals you tell it you eat, and separately shows the research backed minimum of about 0.4 g per kg of body weight per meal. For 75 kg that floor is 30 g, roughly what a large chicken breast or five eggs provides.

A worked lean mass example

A 65 kg woman cutting hard at 18 percent body fat: lean mass is 65 × (1 − 0.18) = 53.3 kg. On the aggressive cut band of 2.3 to 3.1 g per kg of lean mass, that is 53.3 × 2.3 = 122.6 g at the low end and 53.3 × 3.1 = 165.2 g at the high end, a midpoint of about 144 g. Compare that with the ordinary muscle gain and fat loss band applied to the same 65 kg: 1.6 to 2.2 g per kg gives 104 to 143 g, midpoint 124 g. The lean mass basis lands 20 g higher here, because at 18 percent body fat a meaningful share of her total weight is fat mass that does not need feeding with protein, so pricing the target off lean tissue rather than total weight keeps the number honest as body fat drops. The calculator runs both versions and uses whichever is higher, so a heavier or higher body fat cutter never sees the number step down just because they entered a body fat percentage.

Which multiplier applies to you, and why the range is wide

Protein research does not converge on one number because the goal changes the requirement. Someone sitting at a desk and someone cutting fat before a competition are not the same problem, so the calculator uses four bands instead of one figure.

RDA, 0.8 g per kg

This is the minimum to avoid deficiency in a sedentary adult, set by national dietary reference bodies. It is not a target for anyone training. Treat it as a floor, not a goal.

Active or general fitness, 1.2 to 1.6 g per kg

Covers people training a few times a week without a specific physique goal. It is enough to support recovery and modest gains without much thought, which is why it works as a sensible default for the calorie deficit calculator crowd who just want to eat reasonably.

Building muscle or losing fat, 1.6 to 2.2 g per kg

The range most resistance training research settles on for maximising muscle gain or preserving muscle in a deficit. A meta-analysis of controlled trials found gains plateaued around 1.6 g per kg, with little extra benefit above that for most lifters, so this band is where the evidence is strongest.

Lean mass basis, 2.3 to 3.1 g per kg of lean mass

When you enter a body fat percentage on the fat loss goal, the calculator runs a second range based on lean tissue instead of total weight, at 2.3 to 3.1 g per kg of lean mass, and automatically uses whichever of the two ranges, total weight or lean mass, is higher. At higher body fat percentages the total weight range usually wins. As body fat drops the lean mass range overtakes it well before the cut would count as aggressive, so do not expect this to switch on only at a very low body fat.

Protein targets at a glance

The table below shows the same four bands applied across a range of body weights, using the midpoint of each range. The aggressive cut column assumes about 15 percent body fat as a working example; the calculator uses your actual body fat percentage when you provide one.

Spreading protein across the day

How much you eat in a day matters more than how you time it, but timing is not irrelevant. Muscle protein synthesis responds to each meal that contains enough protein, and the response flattens off above a certain amount per sitting.

The 0.4 g per kg floor

A 2018 review of dose response studies put the per meal threshold at roughly 0.4 g per kg of body weight, spread across at least four meals a day, to maximise the muscle building response from each one. Below that, a meal contributes less to the daily signal even if the day total is fine.

Why four meals, not two

Two very large meals can hit your daily total but waste some of the per meal response, because intake above roughly 0.4 to 0.55 g per kg in one sitting shows diminishing returns for stimulating muscle protein synthesis, even though it still counts toward digestion and the day total. Four evenly spaced meals get more out of the same total.

Why the muscle gain and fat loss ranges overlap

It looks like a coincidence that building muscle and losing fat share the same 1.6 to 2.2 g per kg range, but it is not. In both cases the job protein does is the same: support muscle protein synthesis and limit breakdown, whether you are trying to add tissue in a surplus or hold onto it in a deficit.

The difference shows up at the edges. In a surplus, going above 2.2 g per kg rarely adds anything because there is already enough building material and the limiting factor is training stimulus, not protein. In a deep deficit, going toward the top of the range, or higher still when lean mass is used as the basis, becomes more important because the body is actively short of calories and protein is the nutrient most protective against muscle loss under that pressure.

Protein, satiety and the thermic effect in a deficit

Protein does more than protect muscle in a deficit, it also makes the deficit itself easier to hold. Of the three macronutrients, protein has the highest thermic effect, the energy your body spends digesting, absorbing and processing what you eat: roughly 20 to 30 percent of protein calories are spent this way, against roughly 5 to 10 percent for carbohydrate and close to zero for fat (Westerterp, 2004). A gram of protein at the top of your range therefore returns slightly fewer net calories than the same gram counted at face value, a small but real assist while cutting.

Protein is also the most satiating macronutrient per calorie, which matters more in a deficit than in a surplus, when hunger is already working against adherence. In a controlled feeding trial, raising protein's share of total calories led people to spontaneously eat less later in the day without being told to restrict, an effect linked to protein's influence on hormones that signal fullness (Weigle et al, 2005). Neither effect is large enough to change which multiplier you use, but both are part of why the higher end of the range is worth defending on a cut rather than trimmed first to save calories.

How to use your protein target

Treat the number as a daily minimum to hit consistently, not a ceiling to avoid. Protein is the macro most people undershoot, so build meals around it first and fill the rest of your calories with carbs and fats.

Start with sources, not a target you can not hit

Lean meat, fish, eggs, dairy and, for higher volumes, a protein shake are the easiest ways to close the gap without adding a lot of extra calories. A shake with 30 to 40 g of whey or plant protein is a reasonable way to hit a meal that would otherwise fall short.

Recalculate when your weight or goal changes

The target is a percentage of your current weight, so it moves as you gain or lose. Rerun the calculator every 5 kg change or when you switch from cutting to building, whichever comes first.

Common mistakes

Basing the target on goal weight instead of current weight. Protein needs track the body you have now, not the one you are aiming for. Recalculate as you change, do not calculate once for the end state.

Skipping breakfast and loading up at dinner. One 80 g meal is not the same as two 40 g meals for the per meal response. Spread the total across the day.

Confusing protein grams with protein powder scoops. A typical scoop of whey is 20 to 25 g of protein, not the full serving size on the tub, which often includes other ingredients.

Not entering body fat on a cut. The calculator automatically switches to the lean mass basis whenever it produces a higher number than the total weight range, which can happen well before a cut would count as aggressive. Enter your body fat percentage so it can run that comparison.

Assuming more is always better. Above roughly 2.2 g per kg in a surplus or maintenance phase, extra protein mostly displaces carbs and fats without adding muscle. It is not harmful for a healthy adult, just not doing extra work.

Where this estimate breaks down

These ranges come from research on healthy, resistance trained adults, and they hold up reasonably well across that group. They are less reliable outside it.

If you have kidney disease, the usual advice is to keep protein lower and closer to the RDA, under medical guidance, since higher intakes increase renal workload. Older adults sometimes need the upper half of the active range even without training, because muscle maintenance gets harder with age regardless of activity. And a body fat percentage entered from a rough visual estimate, rather than a scan or reliable caliper reading, will throw off the lean mass based range more than it helps, so use total body weight instead if you are not confident in the number.

Plant vs animal protein quality

Every gram figure on this page assumes a mixed diet with a reasonable share of high quality protein, and protein quality is not uniform. Animal sources such as meat, fish, eggs and dairy are complete, digest efficiently, and are relatively dense in leucine, the amino acid most directly tied to triggering muscle protein synthesis. Many plant sources are lower in one or more essential amino acids, digest somewhat less completely, and deliver less leucine per gram of protein, so a given intake of plant protein produces a smaller anabolic response than the same intake of animal protein (van Vliet et al, 2015).

That is not a reason to abandon the ranges above if you eat mostly or only plant protein, only a reason to pay more attention to hitting them. Combining sources across the day, legumes with grains, for example, and leaning on a concentrated plant protein like soy or pea isolate for some meals, closes most of the gap in essential amino acid coverage. Sticking to the higher end of your goal range, as the FAQ on vegetarians and vegans below suggests, is a simple, practical adjustment rather than a precise correction, since no calculator can weigh your actual amino acid intake meal by meal.

Soy protein is the closest plant source to a complete, animal-like amino acid profile and is a reasonable exception to treat like any other source at the ranges above. Most other single plant sources, beans and rice or oats on their own, are worth pairing with something else across the day rather than relied on alone, particularly for anyone eating a purely plant based diet at the muscle building or aggressive cut end of this page rather than just meeting the RDA.

How coaches use a protein calculator

For a coach, the number from this calculator is the opening move of a nutrition plan, not the whole plan. It sets the protein target; the coaching is in making sure the client actually eats it, meal after meal, for months.

A workable routine: set the target and a rough per meal split at onboarding, then check adherence weekly rather than daily, since one off day rarely matters if the average holds. Adjust the target only when body weight or the training goal changes, not on a whim.

Scraler builds that into the client view: set a protein target per client, let them log meals in the app, and see daily and weekly protein adherence next to their weight trend in one place instead of piecing it together from screenshots. See nutrition coaching for how the targets and logging connect.