Daily Protein Calculator
Calculates your optimal daily protein intake in grams based on body weight, activity level, fitness goal, and age. Use it when structuring a diet for muscle building, fat loss, or healthy ageing.
About this calculator
Protein requirements are not fixed — they scale with how much you weigh, how hard you train, and what you are trying to achieve. This calculator uses the formula: daily protein (g) = bodyWeight × activityMultiplier × goalMultiplier × ageMultiplier, where the age multiplier is 1.2 for adults over 65 (reflecting research showing older adults need more protein to combat muscle loss) and 1.0 otherwise. Activity multipliers typically range from around 0.8 (sedentary) to 1.8 (very active), and goal multipliers adjust further for muscle gain versus fat loss versus maintenance. The result gives grams of protein per day. General evidence-based ranges are 0.8 g/kg for sedentary adults, 1.6–2.0 g/kg for those seeking muscle hypertrophy, and up to 2.4 g/kg during aggressive fat loss to preserve lean mass.
How to use
Example: 75 kg person, age 35, moderately active (multiplier 1.4), goal = muscle gain (multiplier 1.6). Step 1 — base: 75 × 1.4 = 105. Step 2 — apply goal multiplier: 105 × 1.6 = 168 g. Step 3 — age check: 35 < 65, so age multiplier = 1.0; final result = 168 g protein per day. Now for a 70-year-old, 70 kg, sedentary (1.0), maintenance goal (1.0): 70 × 1.0 × 1.0 × 1.2 = 84 g/day, reflecting the increased needs of older adults.
Frequently asked questions
How much protein should I eat per day to build muscle?
For muscle hypertrophy, the current evidence-based consensus recommends 1.6–2.2 g of protein per kilogram of body weight per day. This calculator applies a goal multiplier for muscle building that pushes your result toward the higher end of this range, particularly if your activity level is high. Spreading intake evenly across 3–4 meals of 30–40 g each maximises muscle protein synthesis compared with consuming the same amount in one or two large servings. Total daily intake matters more than exact timing, but consistency across days is key.
Why do older adults need more protein than younger people?
From around age 65, the body becomes less efficient at converting dietary protein into new muscle tissue — a phenomenon called anabolic resistance. To achieve the same muscle-building stimulus as a younger adult, older people need to consume roughly 20–40 % more protein per meal and per day. This is why this calculator applies a 1.2 age multiplier for those over 65, nudging recommendations toward 1.0–1.3 g/kg even for relatively sedentary individuals. Adequate protein intake in older adults is strongly linked to reduced risk of sarcopenia, falls, and functional decline.
What happens if you eat more protein than your body needs?
Unlike fat, protein cannot be stored in a dedicated reserve — excess is either oxidised for energy or, in large surpluses, converted to fat. For most healthy people, protein intakes well above recommended levels (even 3+ g/kg) appear safe, with no convincing evidence of kidney damage in those without pre-existing renal disease. The main practical downsides are the added cost, digestive discomfort at very high intakes, and displacing other important macronutrients. If you consistently exceed your calculated target by a large margin, it is worth reviewing your overall calorie balance.