Post-Workout Protein Timing Calculator

Muscle protein synthesis, MPS, is the process of building new muscle tissue. Two things drive it: a resistance training stimulus and dietary protein. Getting both of those roughly right matters far more than getting the timing exactly right.

How much protein per meal

Moore and colleagues (2015) pooled the dose-response studies and found synthesis topped out at about 0.24 g of protein per kg of body weight in a meal for young men, and about 0.40 g/kg for older men. Schoenfeld and Aragon (2018) then recommended 0.4 g/kg a meal, spread over at least four meals, as a practical target for anyone training. This calculator uses that 0.4 figure, and the reason is worth explaining because most calculators quietly use the bottom of the range.

Leucine is the actual trigger, and the arithmetic has to work

MPS is switched on by leucine crossing a threshold, not by protein in the abstract. That threshold is roughly 2.5 g of leucine for a young adult and about 3 g for someone over about 60, whose muscle is less responsive to the same signal.

Now the arithmetic. Leucine content varies by source. The rows below are rounded from Gorissen and colleagues (2018), who measured whey at 11%, milk at 9%, egg at 7%, pea protein at about 7.1%, brown rice protein at 7.3%, wheat at 6.2% and hemp at 5.1%:

At 0.25 g/kg, a 75 kg person eating chicken gets 19 g of protein and about 1.5 g of leucine, which does not reach the threshold. At 0.4 g/kg they get 30 g and 2.4 g, a hair under. That is why this calculator uses the higher figure and then checks the leucine result against the threshold instead of assuming it clears.

Bigger servings are not wasted either, which is a recent change. The old idea that anything past about 25 g in one sitting is simply burned off took a knock in 2023, when Trommelen’s group in Maastricht gave trained young men either 25 g or 100 g of protein after a workout. The 100 g dose drove more muscle building, and kept it going for more than 12 hours. So 0.4 g/kg a meal is a sensible dose to plan around, not a ceiling.

The 0.4 figure is used here to decide how many meals your daily total needs splitting into. The actual per-meal dose then comes from dividing the total by that count, which lands close to 0.4 g/kg and, more importantly, means the meal plan and the daily target are the same number rather than two numbers that disagree by 10%.

The anabolic window is wider than you were told

The old 30-minute window was overstated to the point of being wrong. Current evidence puts the period of elevated protein sensitivity at 4 to 6 hours after training, and possibly up to 24. If you ate a protein-containing meal 1 to 2 hours before training, that meal is still being digested and you have plenty of time. Train genuinely fasted and the picture changes: getting protein in within 30 to 60 minutes does matter, because there is nothing circulating.

Daily total

The build range is Morton’s 2018 meta-analysis: gains stopped improving at about 1.6 g/kg, with the top of the estimate at 2.2. The cut range is Helms and colleagues’ 2.3 to 3.1 g per kg of lean mass, turned into body weight for someone at about 20% fat.

The cut figure being the highest surprises people. In a calorie deficit the body is more willing to break down muscle for fuel, so protein needs go up rather than down. This is the single most common mistake in a diet phase.

How the day is split matters too. In Areta’s 2013 study, 80 g of whey over 12 hours built more muscle protein as four 20 g doses than as two of 40 g or eight of 10 g.