Hong Life CalculatorsUnderstanding the protein intake calculator — concept and principle
This calculator turns your body weight and goal into a daily protein target in grams, splits it over four meals and shows how many calories it supplies. It suits people building muscle, dieting, ageing or checking whether they eat enough protein.
How it is calculated
- Protein per day (g) = weight (kg) × grams per kg for your goal.
- Per meal = daily protein ÷ 4.
- Calories from protein = daily protein × 4 kcal/g.
Goal factors: 0.8 g/kg (general adult RDA), 1.2 g/kg (older or active adults), 1.8 g/kg (muscle gain, middle of 1.6–2.2) and 2.4 g/kg (cutting while preserving muscle).
The principle
The RDA of 0.8 g/kg is set to cover the minimum needs of nearly all healthy adults, based on nitrogen-balance studies; it is a floor, not an optimum. Resistance training increases muscle protein synthesis, and a 2018 meta-analysis found that the benefit of extra protein on muscle gain plateaued around 1.6 g/kg, with 2.2 g/kg as a generous upper limit. In a calorie deficit the body is more likely to break down muscle, so higher intakes help preserve it; contest-prep guidance suggests 2.3–3.1 g per kg of lean mass, which the 2.4 g/kg option approximates using total weight. Older adults respond less to each meal ("anabolic resistance"), so expert groups suggest at least 1.0–1.2 g/kg.
Worked example
- Inputs: 75 kg, goal muscle gain (1.8 g/kg).
- Protein per day = 75 × 1.8 = 135 g.
- Per meal = 135 ÷ 4 = 33.75, shown as 34 g.
- Calories from protein = 135 × 4 = 540 kcal.
| Weight (kg) | Protein per day (g) |
|---|---|
| 18.8 | 34 |
| 37.5 | 68 |
| 56.2 | 101 |
| 75 | 135 |
| 93.8 | 169 |
| 112 | 203 |
| 150 | 270 |
How to read the result
About 0.3–0.4 g/kg per meal (here about 23–30 g) is a common per-meal target, so 34 g across four meals is well spread. If 540 kcal is a large share of a low-calorie diet, that is expected while cutting. If you have a lot of body fat, base the target on goal weight or lean mass rather than total weight, or the number becomes unrealistically high.
Common mistakes
- Counting the weight of a food (a 100 g chicken breast) as 100 g of protein; it provides roughly 20–30 g depending on whether it is weighed raw or cooked.
- Eating almost all protein at dinner and very little at breakfast.
- Assuming more is always better beyond about 2.2 g/kg for muscle gain.
Frequently asked questions
Is high protein bad for healthy kidneys?
Studies in healthy people have not shown harm from intakes up to about 2 g/kg; people with reduced kidney function are different.
Do I need protein shakes?
No. Shakes are a convenience; food such as meat, fish, eggs, dairy, tofu and legumes can supply the same amount.
Should I use total or lean body weight?
For most people total weight works. For people with obesity, goal weight gives a more sensible target.
Sources: Morton RW et al. British Journal of Sports Medicine 2018. · Jäger R et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition 2017. · Bauer J et al. Evidence-based recommendations for optimal dietary protein intake in older people (PROT-AGE). Journal of the American Medical Directors Association 2013.