Free tool · Cantein Research
Amino Acid Calculator
Log what you ate today. Get your optimal protein target, see your biggest essential amino acid gaps, and find the foods and amounts that close them.
Step 3
Your results
Enter your age and weight to see your protein and amino acid targets.
How it works
A protein and amino acid check-up for one day of food
Cantein’s Amino Acid Calculator is a free nutrition tool that compares one day of food against optimal—not minimum—protein and essential amino acid targets for your age, sex, weight, body fat, and training.
Tell it about you
Age, sex, weight, activity, and body fat. No body fat number? Estimate it with a tape measure using the US Navy method.
Log a day of food
Pick from 85 foods with USDA amino acid data: meat, fish, eggs, dairy, legumes, grains, nuts, seeds, vegetables, and protein powders.
Close the gaps
See your protein target, all nine essential amino acids against optimal and minimum levels, a per-meal leucine check, and a food plan that closes what is missing.
Methodology
How your targets are set
Daily protein target
Your target is grams of protein per kilogram of body weight, chosen by activity. The minimum shown for reference is the RDA of 0.8 g/kg. Adults 65 and older never go below 1.2 g/kg.
| Activity | Target | Range | Basis |
|---|---|---|---|
| Mostly sedentary | 1.2 g/kg | 1.2–1.6 g/kg | Intakes above the RDA support muscle and metabolic health (Phillips et al., 2016) |
| Active | 1.4 g/kg | 1.4–2.0 g/kg | ISSN position stand for exercising adults (Jäger et al., 2017) |
| Strength training | 1.6 g/kg | 1.6–2.2 g/kg | Muscle gains plateau near 1.6 g/kg in a meta-analysis of 49 trials (Morton et al., 2018) |
| Strength training + fat loss | 2.2 g/kg | 2.0–2.6 g/kg | ISSN: 2.3–3.1 g/kg of lean mass while in a calorie deficit |
| Age 65+ | At least 1.2 g/kg | 1.0–1.5 g/kg | 1.0–1.2 g/kg for healthy older adults, more with exercise or illness (PROT-AGE, Bauer et al., 2013; ESPEN, Deutz et al., 2014). We use the top of the healthy range. |
Lean-mass adjustment
Protein needs follow lean mass, not fat mass. If your body fat is above 15% (men) or 25% (women), the calculator uses your lean mass divided by 0.85 or 0.75—the weight you would be at that body fat with your current muscle. If you leave body fat blank, it uses your total weight. All per-kilogram targets on this page use that same weight.
Essential amino acid targets
The minimum is the WHO/FAO/UNU (2007) requirement per kilogram. The optimal target applies WHO’s adult amino acid pattern—milligrams of each essential amino acid per gram of protein—to your optimal protein target. In plain terms: it is what you would get by hitting your protein target with high-quality protein.
| Amino acid | Minimum (mg/kg/day) | Optimal pattern (mg/g protein) | Example: 75 kg at 1.6 g/kg |
|---|---|---|---|
| Histidine | 10 | 15 | 1.8 g |
| Isoleucine | 20 | 30 | 3.6 g |
| Leucine | 39 | 59 | 7.1 g |
| Lysine | 30 | 45 | 5.4 g |
| Methionine + cysteine | 15 | 22 | 2.6 g |
| Phenylalanine + tyrosine | 25 | 38 | 4.6 g |
| Threonine | 15 | 23 | 2.8 g |
| Tryptophan | 4 | 6 | 0.7 g |
| Valine | 26 | 39 | 4.7 g |
Per-meal targets
Muscle protein synthesis responds to each meal, not just the daily total. The calculator checks breakfast, lunch, and dinner for about 0.4 g/kg of protein if you are 65+ or strength training (0.3 g/kg otherwise), and for a leucine dose of 2.5 g (3 g at 65+).
Food data and suggestions
Food values come from USDA FoodData Central (SR Legacy). Cantein values come from our bag labels; the labels do not list cysteine, so we estimate it from USDA hemp seed’s ratio of cysteine to methionine. Whey and pea protein powders use typical label protein (24 g per 30 g scoop) with USDA whey and pea protein profiles, so treat them as estimates. Amino acids are not adjusted for digestibility, and plant proteins are usually somewhat less digestible than animal proteins.
Suggested foods are ranked by how much of your remaining gaps they close per calorie, filtered by your diet, with realistic portion limits.
Reference
The 9 essential amino acids and where to get them
Sources are ranked by milligrams per calorie using the calculator’s food data. Concentrated powders rank high because they are mostly protein.
| Amino acid | Why it matters | Top animal sources | Top plant sources |
|---|---|---|---|
| Leucine | The main trigger for muscle protein synthesis after a meal. | Egg whites, whey, tuna, cod | Soy protein, spirulina, hemp protein, pea protein |
| Lysine | Needed for collagen cross-links and carnitine. Usually the first to run short on plant-heavy diets. | Tuna, cod, shrimp, chicken | Soy protein, pea protein, edamame, tofu, lentils |
| Methionine + cysteine | Sulfur amino acids for glutathione, taurine, and methylation. Often lowest in legumes. | Egg whites, tuna, cod, whey | Hemp protein, soy protein, spirulina, Brazil nuts |
| Isoleucine | Branched-chain amino acid burned for energy in muscle; involved in blood sugar regulation. | Egg whites, whey, tuna, cod | Soy protein, spirulina, hemp protein, tofu |
| Valine | Branched-chain amino acid used for muscle repair and energy. | Egg whites, tuna, cod, whey | Soy protein, spirulina, hemp protein, tofu |
| Threonine | Abundant in the mucins that line the gut; used to build collagen and elastin. | Whey, tuna, cod, egg whites | Spirulina, soy protein, hemp protein, tofu |
| Phenylalanine + tyrosine | Building blocks of dopamine, norepinephrine, and thyroid hormones. | Egg whites, tuna, cod, shrimp | Soy protein, hemp protein, spirulina, tofu |
| Tryptophan | Precursor of serotonin, melatonin, and niacin. | Whey, tuna, cod, egg whites | Soy protein, spirulina, pea protein, tofu, pumpkin seeds |
| Histidine | Precursor of histamine and carnosine; needed for growth and tissue repair. | Pork tenderloin, tuna, cod, chicken | Hemp protein, soy protein, pea protein, tofu |
FAQ
Frequently asked questions
How much protein do I need per day?
The RDA of 0.8 g per kg of body weight is a minimum to prevent deficiency, not an optimal intake. Research supports about 1.2–1.6 g/kg for general health, 1.6–2.2 g/kg if you strength train, and at least 1.2 g/kg for adults 65 and older. The calculator picks a target inside those ranges from your activity, age, and body fat.
What are the 9 essential amino acids?
Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Your body cannot make them, so they have to come from food. Cysteine and tyrosine can cover part of the need for methionine and phenylalanine, which is why WHO counts those pairs together.
What is the difference between the minimum and optimal amino acid targets?
The minimum is the WHO/FAO/UNU requirement, set to keep a healthy adult in nitrogen balance at a basic protein intake. Optimal is the amount of each amino acid you would get by meeting a higher, evidence-based protein target with high-quality protein, which is more relevant for muscle, training, and aging.
Can you get all essential amino acids on a vegan diet?
Yes. Most plant foods contain all nine essential amino acids, just in different proportions: legumes run low in methionine and cysteine, while grains and hemp run low in lysine. Mixing plant proteins, leaning on soy, lentils, and seeds, and eating a little more total protein closes most gaps.
What is the leucine threshold?
Leucine is the amino acid that switches on muscle protein synthesis after a meal. Studies suggest roughly 2–3 g of leucine per meal maximizes the response, with older adults needing the higher end. The calculator checks each logged meal against 2.5 g, or 3 g if you are 65 or older.
How accurate is the US Navy body fat method?
It estimates body fat from your height and neck, waist, and hip measurements. For most adults it lands within a few percentage points of lab methods, and it is less accurate at very low or very high body fat. Careful, repeated measurements make the biggest difference.
Is hemp protein a complete protein?
Yes. Hemp contains all nine essential amino acids, but lysine is its limiting amino acid, so it scores lower than soy or whey on protein-quality scales. Pairing hemp with lysine-rich foods such as lentils, tofu, or pea protein balances it. See the hemp protein research.
Does the calculator store my data?
Your profile and food log stay in your browser and are never sent to Cantein. They are saved on your own device so they are still there when you come back, and Reset clears them. The one exception: when a food search finds no match, we record the words you searched, and nothing else, so we can add missing foods.
Is this medical advice?
No. It is an educational estimate for healthy adults. If you have kidney disease, are pregnant or breastfeeding, or follow a medically prescribed diet, talk with your clinician before changing your protein intake.
Source library
Sources
- WHO/FAO/UNU Expert Consultation. Protein and amino acid requirements in human nutrition.WHO Technical Report Series 935, 2007.
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids.National Academies Press, 2005.
- Phillips, Chevalier & Leidy. Protein “requirements” beyond the RDA: implications for optimizing health.Applied Physiology, Nutrition, and Metabolism, 41(5), 2016.
- Jäger et al. International Society of Sports Nutrition position stand: protein and exercise.Journal of the International Society of Sports Nutrition, 14, 2017.
- Morton et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength.British Journal of Sports Medicine, 52(6), 2018.
- Bauer et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group.Journal of the American Medical Directors Association, 14(8), 2013.
- Deutz et al. Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group.Clinical Nutrition, 33(6), 2014.
- Moore et al. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men.Journals of Gerontology: Series A, 70(1), 2015.
- Schoenfeld & Aragon. How much protein can the body use in a single meal for muscle-building?Journal of the International Society of Sports Nutrition, 15, 2018.
- Katsanos et al. A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly.American Journal of Physiology: Endocrinology and Metabolism, 291(2), 2006.
- Hodgdon & Beckett. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height.Naval Health Research Center, Reports 84-11 and 84-29, 1984.
- U.S. Department of Agriculture, Agricultural Research Service. FoodData Central: SR Legacy.2018.
- Mariotti & Gardner. Dietary protein and amino acids in vegetarian diets—a review.Nutrients, 11(11), 2019.
- House, Neufeld & Leson. Evaluating the quality of protein from hemp seed products through the use of the protein digestibility-corrected amino acid score method.Journal of Agricultural and Food Chemistry, 58(22), 2010.
- Meléndez-Hevia et al. A weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis.Journal of Biosciences, 34(6), 2009.
Not medical advice. This calculator gives educational estimates for healthy adults 18 and older. Talk with your clinician before changing protein intake if you have kidney disease, are pregnant or breastfeeding, or follow a medically prescribed diet. Corrections: info@cantein.com.