How the protein calculator works
Protein needs scale with body size, so the calculator multiplies your body weight by a range in grams per kilogram (g/kg) that matches your goal. Each range comes from a published source:
| Goal | g per kg a day | g per lb a day | Source |
|---|---|---|---|
| Sedentary / general health | 0.8–1.0 | 0.36–0.45 | Recommended Dietary Allowance, US Institute of Medicine (2005) |
| Active or endurance training | 1.4–2.0 | 0.64–0.91 | International Society of Sports Nutrition (ISSN) position stand, Jäger et al. (2017) |
| Build muscle | 1.6–2.2 | 0.73–1.0 | Morton et al., meta-analysis, British Journal of Sports Medicine (2018) |
| Lose fat, keep muscle | 1.8–2.7 | 0.82–1.22 | Phillips & Van Loon, Journal of Sports Sciences (2011) |
Daily protein (g) = body weight (kg) × g/kg range for your goal Per meal (g) = daily target ÷ meals a day
The calculator shows the middle of the range as your daily target, plus the full range.
Two adjustments
- Lean mass for fat loss. If you choose the fat loss goal and enter your body fat percentage, the calculator works from lean body mass instead, at 2.3–3.1 g per kg of lean mass. That range comes from a review of studies in lean, resistance-trained people dieting to lose fat (Helms et al., 2014) and is the one the ISSN cites for that situation. It stops people with higher body fat getting an inflated target.
- Age 65 and over. For older adults the minimum rises to 1.0–1.2 g per kg, following the PROT-AGE study group (Bauer et al., 2013), because muscle responds less to protein with age.
Per meal
Research summarised by the ISSN suggests about 0.25 g of protein per kg of body weight at a meal, typically 20–40 g, is enough to fully stimulate muscle protein synthesis for most people. The calculator shows this figure next to your even per-meal split.
Worked example
A 30-year-old man weighing 180 lb (81.6 kg) who lifts weights 4 times a week and wants to build muscle:
- Range = 81.6 × 1.6 to 81.6 × 2.2 = 131–180 g a day
- Daily target (middle of the range) = 155 g
- Across 4 meals = about 39 g per meal
- Per-meal amount that maximises muscle building = 0.25 × 81.6 = about 20 g, so 39 g per meal comfortably covers it.
If he switched to cutting at 90 kg (198 lb) and 30% body fat, his lean mass would be 63 kg and his range 63 × 2.3 to 63 × 3.1 = 145–195 g a day. Using total body weight at 1.8–2.7 g/kg would give 162–243 g, more than he needs.
For a 70-year-old woman weighing 68 kg (150 lb) who is not very active, the RDA range of 54–68 g is raised to 68–82 g a day (1.0–1.2 g/kg).
Protein by body weight
Grams of protein a day for each goal, by body weight:
| Body weight | Sedentary / general health 0.8–1 g/kg | Active or endurance training 1.4–2 g/kg | Build muscle (strength training) 1.6–2.2 g/kg | Lose fat, keep muscle 1.8–2.7 g/kg |
|---|---|---|---|---|
| 110 lb (50 kg) | 40–50 g | 70–100 g | 80–110 g | 90–135 g |
| 130 lb (59 kg) | 47–59 g | 83–118 g | 94–130 g | 106–159 g |
| 150 lb (68 kg) | 54–68 g | 95–136 g | 109–150 g | 122–184 g |
| 170 lb (77 kg) | 62–77 g | 108–154 g | 123–170 g | 139–208 g |
| 190 lb (86 kg) | 69–86 g | 121–172 g | 138–190 g | 155–233 g |
| 210 lb (95 kg) | 76–95 g | 133–191 g | 152–210 g | 171–257 g |
| 230 lb (104 kg) | 83–104 g | 146–209 g | 167–230 g | 188–282 g |
| 250 lb (113 kg) | 91–113 g | 159–227 g | 181–249 g | 204–306 g |
Getting enough protein
- Build each meal around a protein source: eggs, Greek yoghurt, cottage cheese, chicken, fish, lean meat, tofu, tempeh, lentils or beans.
- Spread it out. Three to five meals with 20–40 g each is easier to hit than one large serving at dinner.
- Count protein in grams of protein, not grams of food. 100 g of cooked chicken breast has about 30 g of protein; 100 g of cooked lentils has about 9 g.
- Use shakes if they help. A scoop of whey or plant protein powder usually adds 20–25 g. It is convenient, not necessary.
Protein provides 4 kcal per gram, so 150 g a day is 600 kcal. If you are also counting calories, the macro calculator fits your protein into a full plan with carbs and fat.
Who should be careful
High protein intakes are considered safe for healthy adults. If you have chronic kidney disease, liver disease or another condition where protein is restricted, follow your doctor’s or dietitian’s advice. The calculator is designed for adults, not children or teenagers, and is not tailored to pregnancy, when needs change.
Frequently asked questions
How much protein do I need a day?
The minimum for healthy adults is 0.8 g per kg of body weight (about 0.36 g per lb), the Recommended Dietary Allowance. That prevents deficiency but is not the best amount for building or keeping muscle. People who exercise regularly usually do better on 1.4 to 2.0 g per kg (ISSN, 2017), and people lifting weights to build muscle on about 1.6 to 2.2 g per kg.
How much protein do I need to build muscle?
A 2018 meta-analysis of 49 studies (Morton et al., British Journal of Sports Medicine) found that gains in muscle from strength training levelled off at about 1.6 g of protein per kg of body weight a day, with some people benefiting from up to 2.2 g per kg. That is about 0.7 to 1 g per lb.
Is 1 gram of protein per pound too much?
For healthy people it is a safe, if generous, target. 1 g per lb is 2.2 g per kg, the top of the range for muscle gain. It is a convenient number to remember, especially while dieting, but most people get the full benefit from a little less.
How much protein should I eat per meal?
The ISSN position stand suggests about 0.25 g per kg of body weight per meal, or 20 to 40 g for most people, spread every 3 to 4 hours. Larger servings are not wasted, but spreading protein across meals helps keep muscle building active through the day.
Do older adults need more protein?
Yes. The PROT-AGE study group recommends at least 1.0 to 1.2 g per kg a day for adults over 65, and more for those who are active or recovering from illness, to slow the muscle loss that comes with age. The calculator raises the minimum automatically if you enter an age of 65 or over.
Should I use my current weight or goal weight?
If you carry a lot of body fat, targets based on total body weight can be higher than you need. Entering your body fat percentage with the fat loss goal switches the calculation to lean mass. Alternatively, many dietitians use goal weight for people with obesity.
Is a high protein diet bad for your kidneys?
In healthy people, research has not found that high protein intakes harm kidney function. If you have kidney disease, though, protein may need to be limited, so follow your doctor’s advice rather than this calculator.