Protein Calculator for Muscle Gain: Exactly How Much You Need

What the research says: 1.6–2.2g per kg of body weight

The question of how much protein is needed to maximise muscle gain has been studied extensively over the past two decades. A landmark meta-analysis examining 49 studies and over 1,800 participants found that protein intakes above 1.62g per kilogram of body weight per day did not produce additional gains in lean mass when subjects were engaged in resistance training. The upper boundary of the confidence interval in this analysis was approximately 2.2g/kg.

This establishes the evidence-based range for muscle gain: 1.6–2.2g of protein per kilogram of body weight per day. For practical purposes, most people building muscle should target the middle of this range — around 1.8–2.0g/kg — which provides a comfortable buffer above the minimum effective dose without overcounting.

For individuals who are simultaneously trying to build muscle while in a slight calorie surplus (a "lean bulk"), targeting the lower end of the range (1.6–1.8g/kg) is sufficient. For those attempting to gain muscle while also losing fat (body recomposition), or for natural trainees further along in their training career, the higher end (2.0–2.2g/kg) provides additional insurance against muscle protein breakdown.

Why more protein does not equal more muscle

Once you exceed the effective range, additional protein does not stimulate more muscle protein synthesis — it is simply used for energy or converted to glucose. Eating 3g/kg of protein per day will not build muscle faster than 2.2g/kg in someone who is training consistently and eating enough total calories.

The primary determinants of muscle gain are, in order: progressive overload in training (consistently adding load, volume, or complexity to workouts), total calorie intake (you cannot build tissue without adequate energy), protein quality and quantity (within the effective range), sleep and recovery, and individual factors like training history and genetics.

Very high protein intakes do have one practical advantage: protein is the most satiating macronutrient, so eating more of it tends to reduce total calorie intake naturally. For this reason, high-protein diets (1.8–2.2g/kg) are effective for body recomposition where fat loss and muscle gain are happening simultaneously. But for pure muscle gain in a surplus, eating 4g/kg of protein provides no physiological benefit over 2g/kg.

Leucine: the amino acid that pulls the trigger on muscle growth

Not all proteins are equal when it comes to muscle building. The amino acid leucine plays a unique role as the primary activator of muscle protein synthesis (MPS) via the mTOR pathway — essentially the molecular switch that tells your muscle cells to start building new proteins.

Research suggests there is a leucine threshold of approximately 2–3g per meal required to maximally stimulate MPS. Below this threshold, MPS is only partially activated. This is one reason why protein dose per meal matters — not just daily total.

Whey protein contains around 10–11% leucine by weight, meaning a 25g serving provides ~2.7g of leucine — enough to hit the threshold. Most high-quality animal proteins hit the leucine threshold at around 20–30g of total protein per meal. Many plant proteins have lower leucine concentrations, requiring larger portions to achieve the same anabolic signal.

Meal timing and frequency for muscle protein synthesis

Muscle protein synthesis is transient — it spikes for 2–4 hours after a protein-containing meal, then returns to baseline. To maximise the total MPS signal across the day, the evidence supports spreading protein intake across 3–5 meals, each containing enough protein to exceed the leucine threshold.

For someone targeting 160g of protein per day, four meals of 40g each stimulates more total MPS than two meals of 80g — even though the daily total is identical. Eating 80g of protein in one sitting does not double the anabolic response: the leucine threshold is already exceeded at around 25–35g, and additional protein in the same meal simply does not further stimulate MPS.

Post-workout protein timing: The post-workout "anabolic window" is real but more forgiving than once believed. As long as a substantial protein-containing meal is consumed within 2–3 hours before or after training, the timing advantage is small. Total daily protein intake matters far more than whether you consume your protein shake within 30 minutes of finishing your last set.

Protein quality: complete vs incomplete sources

Complete proteins contain all nine essential amino acids (EAAs) in adequate quantities. Animal proteins — meat, fish, eggs, dairy — are complete. Most plant proteins are incomplete, meaning they are low in one or more essential amino acids.

This does not mean plant-based athletes cannot build muscle — they absolutely can, and research confirms this. However, plant proteins generally have lower digestibility and lower leucine content, meaning:

• You need a slightly larger total daily intake (approximately 10–20% more) to achieve the same anabolic effect.
• Diversifying protein sources throughout the day ensures you cover the full amino acid spectrum.
• Soy protein is the exception — it is a complete plant protein with a relatively high leucine content and comparable anabolic effects to whey in research settings.

A useful practical approach for plant-based trainees: combine legumes (high in lysine, low in methionine) with grains (high in methionine, low in lysine) across meals in a day. You do not need to combine them at every meal — meeting the full amino acid spectrum over the course of the day is sufficient.

Practical protein targets by body weight

A sample high-protein day for muscle gain

Here is what a full day of eating looks like for a 75 kg person targeting 150g of protein per day (2.0g/kg) in a modest calorie surplus for muscle gain:

• Breakfast (40g protein): 3 whole eggs + 4 egg whites scrambled, with 30g reduced-fat cheddar, on 2 slices of wholegrain toast
• Mid-morning snack (25g protein): 200g Greek yoghurt (0% fat) with a scoop of whey protein stirred in and a handful of berries
• Lunch (40g protein): 180g grilled chicken breast + 100g cooked brown rice + large mixed salad with 30g feta and olive oil dressing
• Post-workout (25g protein): Whey protein shake (25g protein scoop) with 300ml semi-skimmed milk
• Dinner (40g protein): 200g lean beef mince bolognese with courgette noodles or 100g cooked pasta

Use our Macro Calculator to set your full macro targets including calories and carbs alongside your protein goal.

Protein supplements: whey vs casein vs plant

Whey protein

Whey is a fast-digesting protein derived from dairy. It has the highest leucine content of common protein supplements (~10–11%) and a complete amino acid profile. It is the most researched protein supplement and has a well-established track record for stimulating MPS post-exercise. Whey concentrate (~70–80% protein) is cheaper; whey isolate (~90% protein) is lower in lactose and fat, useful if you are sensitive to lactose.

Casein protein

Casein is also derived from dairy but digests much more slowly than whey, releasing amino acids gradually over 5–7 hours. This makes it useful before sleep, when you go the longest period without protein. Some research suggests that consuming 30–40g of casein before bed supports overnight muscle protein synthesis and may incrementally improve long-term muscle gain compared to not eating protein before sleep.

Plant protein powders

Pea, rice, hemp, and soy are the most common plant-based protein powders. Pea protein is notably high in branched-chain amino acids (BCAAs) including leucine. Research comparing pea protein to whey in resistance-trained individuals has found largely comparable muscle gain outcomes when daily totals are equivalent. Blended plant proteins (combining two or more sources for a more complete amino acid profile) are generally superior to single-source plant proteins for muscle building.

For creatine — one of the few supplements with strong evidence for improving strength and muscle gain — see our Creatine Calculator for dosing guidance.