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About this tool
Daily and per-meal protein targets for hypertrophy blocks using ISSN g/kg ranges and the 0.4 g/kg per-meal dose.
This calculator turns your bodyweight, body-fat percentage and training phase into a daily protein target and a per-meal dose sized for muscle growth. It applies the ISSN Position Stand range of 1.4-2.0 g per kg bodyweight for building and maintaining muscle, switches to the 2.3-3.1 g per kg fat-free mass range used when dieting down, and then divides the total using the 0.4 g/kg per-meal dose that maximises muscle protein synthesis. It is aimed at lifters running a structured bulk, cut or maintenance block who want the distribution right, not just the daily number.
Open Bodybuilder Protein Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Bulking and maintenance use bodyweight; cutting switches to fat-free mass, as the research does.
Checks every meal against the 0.4 g/kg dose and the ~2.5 g leucine trigger.
Tells you when too many small meals are diluting the per-meal dose, and how many you should eat instead.
The ISSN Position Stand puts it at 1.4-2.0 g per kg of bodyweight per day to build and maintain muscle, so an 85 kg lifter lands around 120-170 g. Intakes at the top of that band, or above it, mainly help when you are also in a calorie deficit.
There is no hard cap on absorption, but about 0.4 g per kg bodyweight per meal — roughly 34 g for an 85 kg lifter — is the dose that maximally stimulates muscle protein synthesis. Eating far more in one sitting is not wasted, it is just used for energy or other tissues rather than adding to that MPS response.
Because fat tissue does not need feeding and scale weight overstates the requirement in anyone carrying extra fat. Research on lean, resistance-trained dieters points to 2.3-3.1 g per kg of fat-free mass to protect muscle in a deficit, which is why the calculator asks for body-fat percentage before using that band.
In healthy adults with normal kidney function, controlled studies of intakes above 2 g/kg for months have not shown harm to kidney or bone health. That evidence does not extend to people with kidney or liver disease, so anyone with an existing condition, or who is pregnant, should get individual advice from a doctor or registered dietitian.
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