Estimate how much protein you need each day to support muscle protein synthesis, split across meals, from weight, height, age, sex and training goal.
lbs
in
Results
Calculated
Daily protein
—
grams per day
Protein per meal
—
grams per meal
Estimated TDEE
—
kcal/day at moderate activity
Protein share of calories
—
% of TDEE
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Protein needs and muscle protein synthesis
Muscle protein synthesis is the process by which your body builds new muscle protein from amino acids. Enough dietary protein, spread across the day and combined with resistance training, keeps it running ahead of muscle breakdown. This calculator turns your body weight and training goal into a daily protein target and a per-meal amount, then compares it with your estimated energy needs.
How it is calculated
Daily protein = body weight in kg × the g/kg factor for your goal (0.8 for general health, 1.2 for active people, 1.6 for muscle gain, 2.0 for heavy training or dieting).
Per meal = daily protein / meals per day. Research suggests roughly 0.25 to 0.4 g/kg per meal maximizes the response.
TDEE = Mifflin-St Jeor BMR (10×kg + 6.25×cm − 5×age, +5 for men or −161 for women) × 1.55 for moderate activity.
Protein share = protein grams × 4 kcal / TDEE.
Worked example
A 35-year-old man weighing 175 lb (79.4 kg) and 70 in (177.8 cm) tall, aiming to build muscle (defaults). Protein = 79.38 × 1.6 = 127 g per day; over 4 meals that is 32 g per meal. BMR = 793.8 + 1,111.3 − 175 + 5 = 1,735 kcal; TDEE = 1,735 × 1.55 = 2,689 kcal. Protein supplies 127 × 4 = 508 kcal, or 18.9% of TDEE.
Common mistakes
Using pounds as kilograms. Enter weight in pounds; the tool converts it.
Eating it all in one meal. Spreading protein across meals is generally considered more effective for muscle building than one large dose.
Ignoring medical conditions. People with kidney disease or other conditions should follow their clinician's advice, not a general calculator.
Frequently Asked Questions
How much protein per day do I need to build muscle?
Studies of resistance training support about 1.6 g per kg of body weight per day for most people, with little added benefit beyond roughly 2.2 g/kg.
Is more protein per meal better?
Not beyond a point. About 0.25 to 0.4 g/kg per meal, or 20 to 40 g for most adults, is enough to maximize the response for a single meal.
Does age change protein needs?
Older adults often need toward the higher end of the range because muscle becomes less responsive to protein, so aim for at least 1.2 g/kg.
Why are height and age needed?
They feed the calorie estimate. They do not change the protein target, which is driven by body weight and goal.
Practical Guide for Protein Synthesis Calculator
Protein Synthesis Calculator is most useful when the inputs reflect the situation you are actually planning around, not a best-case estimate. Treat the result as a decision aid: it gives you a structured way to compare assumptions, spot outliers, and decide what to verify next. For Biology work, the most important review lens is sampling method, growth assumptions, measurement window, variability, and biological context.
Start with a baseline run using values you can defend. Then change one assumption at a time and watch which output moves the most. If one input dominates the result, spend your verification time there first. If several inputs have similar influence, use a conservative scenario and an optimistic scenario to create a practical range instead of relying on a single exact number.
Before acting on the result, compare the result with observed measurements, protocol notes, and expected biological ranges. This is especially important when the calculator supports a purchase, project plan, performance target, or operational decision. The calculator can make the math consistent, but the quality of the conclusion still depends on current data, clear units, and assumptions that match your real constraints.
When the output looks surprising, slow down and inspect each input in order. A small change in one high-leverage field can move the final number more than several low-leverage fields combined. For Protein Synthesis Calculator, that means you should first confirm the value with the greatest scale, then confirm the value with the greatest uncertainty, then rerun the calculator with conservative and optimistic assumptions. This sequence turns the calculator from a single answer into a practical decision range.
Review Checklist
Confirm every input uses the unit and time period requested by the calculator.
Run a low, expected, and high scenario so the answer has a useful range.
Check whether rounding or a missing decimal place changes the decision.
Update the calculation whenever the organism, culture condition, population, or sampling period changes.