How Much Protein Should I Eat Per Day? Calculator

Protein needs vary far more than the old 'one size fits all' RDA suggests. A sedentary 150 lb office worker may do fine on around 55 grams per day (0.36 g/lb), while a 180 lb lifter cutting body fat often targets 160–200 grams (around 0.9–1.1 g/lb) to preserve lean mass. This calculator combines body weight, activity level, training goal, age, and biological sex to estimate a daily protein range, then splits it into 3–5 meals so each serving lands in the 25–45 g window that research links to maximal muscle protein synthesis.

Use the tool as a planning anchor, not a strict rule. For example, a 65 kg recreational runner aiming to maintain muscle might land near 100 g/day (1.5 g/kg), while the same person training for a marathon and lifting 4×/week could push to 130 g/day (2.0 g/kg). The example numbers shown on this page (like 0.8 g/kg or 150 lb body weight) are defaults—you can plug in any realistic weight, age, and goal and the math scales accordingly. Pair the result with adequate calories, fiber, and water for best results.

How it works: Enter your weight, pick an activity level and goal, then add age and sex. The calculator selects a protein-per-kg coefficient from evidence-based ranges, multiplies it by your body weight, adjusts for age (older adults need more) and goal (cutting, maintaining, or building), and splits the daily total across your chosen meal count.

How Much Protein Do You Really Need in 2026?

Protein recommendations have shifted significantly since the 1970s RDA of 0.8 g/kg. Modern sports nutrition research (ISSN, 2017–2024) supports 1.4–2.2 g/kg for active adults, with the upper end during fat loss. Here's how to dial in your number.

Protein targets by goal and activity (grams per kg body weight)

Protein content of common foods

The Outdated 0.8 g/kg RDA

The original 0.8 g/kg recommendation comes from nitrogen balance studies designed to prevent deficiency in sedentary adults—not to optimize body composition, recovery, or healthy aging. For a 70 kg adult, that's just 56 g/day, roughly two chicken breasts. Modern reviews from the International Society of Sports Nutrition consistently show that 1.4–2.0 g/kg produces better outcomes for anyone who exercises. Rule of thumb: treat 0.8 g/kg as the floor that prevents deficiency, not the ceiling for thriving. If you train at all, double it as a starting point and adjust from there.

Protein for Fat Loss

When you're in a calorie deficit, higher protein protects lean muscle and increases satiety through elevated GLP-1 and PYY hormones. Research by Helms et al. suggests 2.3–3.1 g/kg of fat-free mass for lean dieters, which translates to roughly 1.0–1.2 g per pound of body weight for most people. A 180 lb dieter targeting fat loss should aim for 180–220 g protein daily. Practical guideline: when cutting, calculate protein first, fill remaining calories with fats and carbs second. This 'protein-first' approach typically reduces hunger and minimizes the muscle-loss tax of dieting.

Protein for Muscle Gain

Contrary to bro-science, you don't need 400 g of protein to build muscle. Meta-analyses (Morton, 2018) show diminishing returns above ~1.6 g/kg (~0.73 g/lb) for hypertrophy in trained lifters. A 175 lb lifter bulking can do exceptionally well on 130–160 g/day, paired with a modest calorie surplus and progressive overload. Rule of thumb: hit 0.7–1.0 g per lb body weight, ensure each meal contains at least 0.4 g/kg (around 30–40 g for most adults), and prioritize leucine-rich sources like dairy, eggs, and lean meats. More protein beyond this mostly displaces carbs needed for training fuel.

Protein and Aging

Adults over 60 face anabolic resistance—muscle protein synthesis becomes less responsive to the same dose of amino acids. The PROT-AGE expert consensus recommends 1.0–1.2 g/kg for healthy older adults and 1.2–1.5 g/kg for those with acute or chronic illness. For a 150 lb (68 kg) grandparent, that's 80–100 g/day, ideally split into 25–30 g doses per meal. Practical tip: front-load breakfast (most older adults underconsume protein at AM), and combine resistance training with protein for the strongest sarcopenia defense. Whey or skim milk after exercise is especially effective in this group.

How to Split Protein Across Meals

Muscle protein synthesis (MPS) peaks at about 0.4 g/kg per meal, roughly 25–40 g for most adults. Beyond that, additional protein is still useful (anti-catabolic, satiety) but provides diminishing MPS returns within a 3–4 hour window. Practical rule: aim for 3–5 evenly spaced meals containing 25–45 g protein each, not one giant 100 g dinner. A 180 g daily target works well as 4 meals × 45 g, or 5 meals × 36 g. Include a protein-rich meal within 2 hours of training, and consider 30–40 g of slow casein before bed to support overnight recovery.

Plant-Based Protein Considerations

Plant proteins generally have lower digestibility (DIAAS scores) and less leucine per gram than animal sources. Practical workaround: vegans and vegetarians should aim for the upper end of recommended ranges (about 10–20% more), combine complementary sources (legumes + grains, soy + nuts), and consider a leucine-rich isolate like soy or pea protein post-workout. A 70 kg vegan lifter might target 130–150 g instead of 110–130 g. Tofu, tempeh, seitan, lentils, and edamame are the highest-density plant options. With deliberate planning, plant-based eaters can absolutely match the muscle and performance outcomes of omnivores.

Common Protein Myths Debunked

Myth 1: 'High protein damages healthy kidneys.' A 2018 meta-analysis in the Journal of Nutrition found no adverse renal effects in healthy adults consuming up to 2.8 g/kg. Myth 2: 'Your body can only absorb 30 g per meal.' Absorption is nearly 100%—what's capped is the MPS response, not absorption. Myth 3: 'More protein equals more muscle.' Beyond ~1.6 g/kg for lifters, gains plateau. Myth 4: 'You need protein within 30 minutes of training.' The 'anabolic window' is more like 4–6 hours. Rule of thumb: total daily intake and consistency matter far more than precise timing.

How This Calculator Works: Methodology & Parameter Explanations

Core formula: daily_protein_g = body_weight_kg × (base_coefficient + goal_adjustment + age_adjustment + sex_adjustment), where body_weight_kg = body_weight_lb / 2.2046, base_coefficient varies from 0.9 (sedentary) to 2.0 (athlete), and per-meal protein = daily_protein_g / meals.

Assumptions

Coefficients derive from ISSN position stands and the PROT-AGE consensus; ranges are evidence-based, not arbitrary.

The defaults shown (e.g., 160 lb, 32 years old) are starting examples—any realistic weight, age, or goal will recalculate correctly.

Calculator assumes healthy kidney function; people with chronic kidney disease should follow medical guidance.

Protein is modeled at 4 kcal per gram; calorie totals don't include fat or carbohydrate intake.

Per-meal target is a simple division; real-world distribution can vary by ±10–20% without compromising results.

This tool is for general planning, not medical nutrition therapy.

Parameter meanings