The Best Protein Sources — Ranked by Quality and Value
Not all protein is equal. Some foods deliver complete protein with all nine essential amino acids and plenty of leucine — the amino acid that triggers muscle building — in a small, cheap serving. Others are incomplete, low in leucine, or so expensive per gram that they are a poor way to reach a daily target. Knowing the ranking saves money, saves stomach space, and makes the target easier to hit.
This guide ranks the best protein sources by quality and value: the complete proteins at the top, the plant combinations that match them, the leucine content that decides how much muscle a meal builds, and the cost per gram that decides what is practical to eat every day. It is written for anyone trying to eat 100–180 g of protein a day without spending a fortune or eating the same meal forever.
Use the calculator
Start with your own numbers: try our protein calculator, meal calorie calculator to work out your figures before applying anything on this page. The worked examples below use round numbers so you can follow the maths; the calculators use your real weight, height, age and goal.
Related reading: How Much Protein Per Day? The Evidence-Based Ranges, Mediterranean Diet Explained — Why It Keeps Topping the Rankings, Muscle Gain Diet — Calories, Protein and Meal Structure. You can also browse the full guides section for the rest of the series.
The key points
Complete proteins contain all nine essential amino acids. Animal foods — meat, fish, eggs, dairy — are complete by nature, and so are soy foods (tofu, tempeh, edamame) and quinoa among plants. Most other plant proteins are incomplete — low in one amino acid, usually lysine (grains) or methionine (beans) — but combining them across the day (beans with rice, lentils with bread) gives a complete profile. The combination does not have to be in the same meal; the day's total is what matters.
Leucine is the trigger, and 2–3 g per meal is the dose. Leucine is the amino acid that switches on muscle protein synthesis, and a meal needs about 2–3 g of it to trigger the process fully. Whey protein and eggs are rich in leucine (about 2.5 g per 25 g of protein); most plant proteins are lower (about 1.5–1.8 g per 25 g), which is why plant-based eaters need slightly more total protein per meal — about 30–40 g instead of 25–30 g — to reach the same leucine dose.
Eggs are the reference protein. The egg is the standard against which other proteins are measured: complete, high in leucine, cheap, and versatile. One large egg has about 6 g of protein and 0.5 g of leucine; three eggs have 18 g of protein and 1.5 g of leucine — a good start to a meal, though not quite the full trigger dose on their own. The cholesterol in eggs is not the concern it was once thought to be for most people, though anyone with a medical reason to limit it should follow their clinician's advice.
Dairy is the most convenient high-protein food. Greek yoghurt (about 10 g of protein per 100 g), cottage cheese (about 11 g per 100 g) and milk (about 3.5 g per 100 ml) are complete proteins that need no cooking and are easy to eat in large amounts. A 200 g serving of Greek yoghurt with nuts gives 20 g of protein and 2 g of leucine in two minutes — which is why dairy is the backbone of so many high-protein diets, and why lactose-intolerant eaters need a plan to replace it.
Plant proteins work, with planning. Lentils (9 g per 100 g cooked), chickpeas (9 g), black beans (9 g), tofu (8 g) and tempeh (19 g) are the best plant sources, and they bring fibre and micronutrients that animal foods do not. The planning is the leucine dose — aim for 30–40 g of plant protein per meal — and the variety, so the day's amino acids are complete. A plant-based lifter can reach 1.6–2.2 g/kg, but it takes more food volume and more attention than an omnivore's diet.
Cost per gram decides what is practical. The cheapest proteins per gram are usually eggs, milk, lentils, beans, canned tuna and chicken thighs; the most expensive are fresh fish, steak and protein bars. A diet built on the cheap end of the list can hit 150 g of protein a day for a fraction of the cost of one built on salmon and steak — and the muscle does not know the difference, because the amino acids are the same. The ranking by value matters more than the ranking by prestige.
At a glance
| Food | Protein per 100 g | Leucine per 25 g protein | Complete? | Cost per gram |
|---|---|---|---|---|
| Whey protein powder | 80 g | ~2.7 g | Yes | Low |
| Chicken breast | 31 g | ~2.3 g | Yes | Medium |
| Canned tuna | 26 g | ~2.2 g | Yes | Low |
| Greek yoghurt | 10 g | ~2.2 g | Yes | Low |
| Eggs | 13 g | ~2.5 g | Yes | Very low |
| Cottage cheese | 11 g | ~2.3 g | Yes | Low |
| Tempeh | 19 g | ~1.8 g | Yes | Medium |
| Lentils (cooked) | 9 g | ~1.6 g | No* | Very low |
| Black beans (cooked) | 9 g | ~1.6 g | No* | Very low |
| Tofu | 8 g | ~1.7 g | Yes | Low |
| Peanut butter | 25 g | ~1.5 g | No* | Low |
*Incomplete alone, complete when combined with grains across the day. Protein figures are approximate averages from USDA food composition data; cost rankings are indicative and vary by region.
The formula behind it
The cost-per-gram calculation is simple: cost per gram of protein = price ÷ (weight × protein per gram). A dozen eggs costing £2.50 contains 12 × 6 g = 72 g of protein, so the cost is 250 ÷ 72 ≈ 3.5 pence per gram. A chicken breast costing £6 per kg contains 310 g of protein per kg, so the cost is 600 ÷ 310 ≈ 1.9 pence per gram — cheaper than eggs per gram, despite the higher price per kilogram, because the protein density is higher. A protein bar costing £2 for 20 g of protein is 10 pence per gram — five times the cost of chicken, for the same amino acids.
The daily maths is the same as in the protein guide: a target of 1.6–2.2 g/kg a day. At 80 kg and 1.8 g/kg, that is 144 g a day, or about 36 g per meal across four meals. One day built from the cheap end of the table — eggs and Greek yoghurt for breakfast (35 g), lentils and rice for lunch (30 g), chicken for dinner (45 g), cottage cheese for a snack (30 g) — reaches 140 g for a modest cost, with complete amino acids across the day. The calorie context comes from Mifflin-St Jeor (Mifflin et al., 1990): a 30-year-old man, 80 kg, 180 cm, moderately active has a TDEE of about 2,759 kcal, and 144 g of protein is 576 kcal of that total.
Your plan, step by step
- Work out your daily protein target (1.6–2.2 g/kg if you lift or diet) and divide it across 3–4 meals.
- Build each meal around one protein food from the table — aim for 30–40 g per meal.
- If you eat plants, aim for the higher end per meal (30–40 g) and combine beans with grains across the day.
- Use the cheap proteins (eggs, dairy, lentils, beans, chicken, tuna) as the backbone, and the expensive ones as variety.
- Track intake for a week to check you are hitting the target — most people eat 20–30% less protein than they think.
How to use this guide
Use the table to build a rotation, not a single diet. Three or four protein foods per day, rotated across the week, covers the amino acids, the budget and the boredom problem at once: chicken on Monday, fish on Tuesday, lentils on Wednesday, eggs on Thursday, and so on. The variety is not just for enjoyment — different proteins bring different micronutrients, and a varied diet is a more complete one.
Do not chase the "best" protein at the expense of the practical one. The best protein source is the one you will eat, afford and enjoy every day — and for most people that is eggs, dairy, chicken and beans, not the exotic or expensive options. A diet built on the cheap, convenient end of the table and followed for a year beats a diet built on the perfect end of the table and abandoned in a month.
What this guide does NOT tell you
The protein and leucine figures are approximate averages from food composition data (USDA) and the sports-nutrition literature: individual products vary, cooking methods change the numbers slightly, and the cost rankings are indicative and vary by region and season. The leucine threshold of 2–3 g per meal is an average that varies with age and body size — older adults need the higher end.
This guide is general information, not medical advice. The protein ranges are for healthy adults; kidney disease, liver disease and certain metabolic conditions change the answer, and anyone with a medical condition should follow a clinician's protein target. Food allergies (egg, milk, fish, soy, nuts) obviously change which sources are usable, and the ranking should be read with your own dietary needs in mind — not as a prescription to eat foods you cannot or should not eat.
Frequently asked questions
What is the best source of protein for muscle gain?
The best sources are complete proteins rich in leucine: whey protein, eggs, chicken, fish, Greek yoghurt and cottage cheese all deliver 2–3 g of leucine per 25 g of protein, which is the dose that triggers muscle building. Plant sources (tofu, tempeh, lentils, beans) work too, but need slightly more per meal (30–40 g) to reach the same leucine dose. The best source in practice is the one you will eat consistently, afford, and enjoy — usually eggs, dairy and chicken.
Is plant protein as good as animal protein for muscle?
Nearly, with planning: plant proteins are lower in leucine and often incomplete in one amino acid, so plant-based eaters need slightly more total protein per meal (30–40 g) and variety across the day (beans with grains) to match animal protein. Studies comparing plant and animal protein find similar muscle gains when total protein and leucine are matched — the gap is in the dose and the planning, not in the protein itself. Soy foods (tofu, tempeh) are the exception: they are complete proteins.
How much protein is in an egg?
About 6 g in a large egg (about 13 g per 100 g), with about 0.5 g of leucine — so three eggs give 18 g of protein and 1.5 g of leucine. Eggs are the reference protein: complete, high in leucine, cheap, and versatile. Three eggs alone do not quite reach the 2–3 g leucine threshold for a meal, so pair them with another protein food (Greek yoghurt, cheese, beans) to clear it.
What is the cheapest way to eat enough protein?
Eggs, milk, lentils, beans, canned tuna and chicken thighs are usually the cheapest proteins per gram — a dozen eggs or a bag of lentils delivers 70–100 g of protein for very little money. Protein bars, fresh fish and steak are among the most expensive per gram, often five times the cost of chicken for the same amino acids. A diet built on the cheap end of the list can hit 150 g of protein a day for a fraction of the cost of one built on salmon and steak.
Do I need protein powder to build muscle?
No — protein powder is convenient food, not a requirement, and the same grams come from meat, fish, eggs, dairy, beans and tofu. Whey protein is useful because it is complete, high in leucine, and easy to drink when a meal is impractical — but it does not build muscle faster than food, and a diet that reaches its target from ordinary food needs no powder at all. Use it as a tool for convenience, not as a belief about necessity.
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.