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Free Nutrition Tool

Protein Calculator

Get a personalised protein target based on your weight, activity level, and goal, grounded in the 1.6–2.2 g/kg research consensus.

Based on ISSN 2017 & Morton et al. 2018 kg or lbs Free, no sign-up

Enter Your Details

All three inputs affect your target, activity and goal have a bigger impact than most people expect.

Enter your current body weight in kg.

How to Use This Calculator

  1. Enter your body weight

    Use your current body weight, not your goal weight. Protein targets are based on current weight. Toggle between kg and lbs, the calculator converts automatically.

  2. Select your activity level honestly

    "Moderately active" means you train 3–4 times per week with real intensity. If you walk occasionally and do one gym session a week, that is "lightly active." Being honest here prevents under-eating protein.

  3. Choose your primary goal

    Building muscle requires the most protein per kg because you need surplus amino acids for new muscle synthesis. Cutting requires high protein to preserve muscle during a caloric deficit. Maintenance sits in the middle.

  4. Distribute protein across meals

    Each meal should contain 20–50 g of protein to maximise muscle protein synthesis per eating occasion. Four evenly spaced meals covering your daily target is a practical framework for most people.

The Research Behind the Numbers

Key Research Finding

1.62 g/kg/day

The protein intake at which further increases produced no additional gain in lean mass across 49 randomised controlled trials, Morton et al., 2018 (British Journal of Sports Medicine)

The 1.6–2.2 g/kg/day range is the current evidence-based consensus for maximising muscle hypertrophy in adults who resistance train. This figure comes from:

  • › Morton et al. (2018): Meta-analysis of 49 RCTs. Upper 95% CI was 2.20 g/kg, hence the 2.2 g/kg upper bound.
  • › ISSN 2017 Position Stand (Stout et al.): Recommends 1.4–2.0 g/kg for general athletic populations, 2.3–3.1 g/kg lean body mass during severe caloric restriction.
  • › Areta et al. (2013): 20–40 g protein per meal maximises acute muscle protein synthesis. Spreading intake across 4–5 meals outperforms 2-meal or 8-meal patterns.

The RDA (0.8 g/kg) is not a target, it is a minimum designed to prevent nitrogen deficiency in sedentary adults. Active individuals and those seeking to build or preserve muscle need significantly more.

During a caloric deficit, protein requirements increase (up to 2.4–3.1 g/kg) because some dietary protein is oxidised for energy. Higher protein intake during a cut is one of the most evidence-backed strategies for preserving lean mass while losing body fat.

Source Recommendation Population
RDA (WHO/IOM) 0.8 g/kg/day Sedentary adults (minimum)
Morton et al. 2018 1.62 g/kg/day (1.03–2.20) Resistance-trained adults
ISSN 2017 1.4–2.0 g/kg/day Athletic populations
ISSN 2017 (cutting) 2.3–3.1 g/kg LBM/day Caloric deficit / lean athletes
Phillips 2016 1.8–2.7 g/kg/day Masters athletes (>50 yrs)

Frequently Asked Questions

How much protein do I need to build muscle?
The most robust evidence (Morton et al. 2018, meta-analysis of 49 RCTs) puts the effective range at 1.6–2.2 g of protein per kg of body weight per day. Beyond 2.2 g/kg, additional protein produces no further lean mass gains for most people. This calculator targets this research-supported range based on your activity and goal.
Should I eat more protein when cutting?
Yes, higher protein during a caloric deficit (up to 2.4–3.1 g/kg) helps preserve lean muscle mass that would otherwise be lost as the body seeks energy sources. Protein also has the highest thermic effect of food (~25–30% of calories consumed are used in digestion). This calculator adds a meaningful uplift to your protein target when you select the "lose fat" goal.
Does protein source matter, animal vs plant?
Complete proteins, those containing all essential amino acids, especially leucine, are most effective for stimulating muscle protein synthesis (MPS). Animal proteins (whey, eggs, meat, dairy) are generally complete. Plant-based athletes should combine sources and may need 10–20% higher total intake to account for lower leucine density and digestibility. Soy and pea protein are the most complete plant options.
How many protein meals should I eat per day?
Research (Areta et al. 2013) shows that 3–5 evenly spaced meals each containing 20–40 g of high-quality protein maximises 24-hour muscle protein synthesis. A single meal provides only one MPS stimulus; spreading intake provides multiple stimulation events throughout the day.
Is it safe to eat high protein long-term?
In healthy adults with normal kidney function, protein intakes up to 3.5 g/kg/day appear safe based on available evidence (ISSN 2017). The concern about high protein and kidney damage applies to people with pre-existing kidney disease, not healthy individuals. Staying well-hydrated is recommended at higher intakes.

Struggling to Hit Your Protein Target from Whole Foods?

Whole food sources (chicken, eggs, Greek yoghurt, lentils) should be the foundation of your protein intake. When they fall short, a quality protein powder makes up the deficit conveniently. Optimum Nutrition Gold Standard Whey remains the most rigorously tested, transparent-label option in the category.

Affiliate disclosure: we earn a small commission on qualifying purchases at no extra cost to you. Our recommendation reflects the evidence, not the commission rate.

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