Estimate how much dietary protein to eat each day from your age, sex, height, weight, and activity. Switch US and metric units, pick Mifflin St Jeor or Katch-McArdle, and compare American Dietetic Association, CDC, and WHO ranges.
Formula
Calories start with basal metabolic rate (BMR), then an activity factor. Mifflin St Jeor (the default) uses kilograms (W), centimetres (H), and years (A). Katch-McArdle uses lean mass from body-fat fraction (bf):
Men: BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161
Katch: BMR = 370 + 21.6 × W × (1 − bf)
Calories = round(BMR × activity)
Protein recommendations (grams/day, rounded):
ADA sedentary: 0.8W – 1.0W
ADA active: 1.0W – 1.8W
CDC: (calories × 0.10 / 4.1) – (calories × 0.35 / 4.1)
WHO: 0.83W
| Activity level | Factor |
|---|---|
| Sedentary (little or no exercise) | 1.2 |
| Light (1–3 times/week) | 1.375 |
| Moderate (4–5 times/week) | 1.465 |
| Active (daily, or intense 3–4 times/week) | 1.55 |
| Very Active (intense 6–7 times/week) | 1.725 |
| Extra Active (very intense daily, or physical job) | 1.9 |
CDC uses 4.1 kcal per gram of protein (the same metabolizable-energy density as the Macro Calculator), not the rounded 4 kcal/g Atwater figure.
These numbers are typical-situation estimates for healthy adults. Children, athletes, pregnancy, and nursing usually need more. If you have kidney disease, liver disease, diabetes, or another condition where protein is a factor, ask a doctor or registered dietitian before changing how you eat.
Exercise here means 15–30 minutes of elevated heart rate. Intense exercise is 45–120 minutes; very intense is 2+ hours.
What are proteins?
Protein is one of three primary macronutrients (with carbohydrate and fat). It supplies essential amino acids, supports tissues and organs, and does much of the work inside cells — antibodies, enzymes, messengers, structural fibers, and transport molecules are all proteins.
There are 20 amino acids in human proteins. Nine are essential: you have to get them from food. Foods that provide all nine in useful amounts are complete proteins (meat, dairy, eggs, fish, soy, quinoa, buckwheat). Most nuts, seeds, legumes, grains, and vegetables are incomplete on their own — eating a variety across the day still covers the set.
How much protein do I need?
Needs depend on energy intake, growth, and activity. A commonly cited adult RDA is 0.8 g per kilogram of body weight — a minimum to cover basic requirements, not an athlete's target. Practical ranges often sit between about 0.8 and 1.8 g/kg; highly active people who want to build muscle sometimes aim near 1.8–2 g/kg. None of this is an exact science for one person — a dietitian, doctor, or qualified coach can personalize it.
Recommended dietary allowance (RDA) of protein, based on age:
| Age | Protein (grams/day) |
|---|---|
| 1 – 3 | 13 |
| 4 – 8 | 19 |
| 9 – 13 | 34 |
| 14 – 18 (girls) | 46 |
| 14 – 18 (boys) | 52 |
| 19 – 70+ (women) | 46 |
| 19 – 70+ (men) | 56 |
Extra protein for pregnancy and lactation:
| Stage | Extra safe intake (g/day) | Extra energy (kJ/day) | Protein : energy ratio |
|---|---|---|---|
| Pregnancy trimester 1 | 1 | 375 | 0.04 |
| Pregnancy trimester 2 | 10 | 1,200 | 0.11 |
| Pregnancy trimester 3 | 31 | 1,950 | 0.23 |
| Lactation, first 6 months | 19 | 2,800 | 0.11 |
| Lactation, after 6 months | 13 | 1,925 | 0.11 |
Foods high in protein
A mix of meat, dairy, and plants is an easy way to hit a daily target without leaning on any one food. Complete-protein examples include eggs, chicken breast, cottage cheese, Greek yogurt, milk, lean beef, tuna, turkey, fish, shrimp, soy (tofu, tempeh, edamame), quinoa, and buckwheat. Incomplete but useful sources include beans and rice, hummus and pita, peanut butter on toast, hemp and chia seeds, lentils, oats, almonds, and many vegetables.
Amount of protein in common food:
| Food | Protein |
|---|---|
| Milk (1 cup / 8 oz) | 8 g |
| Egg (1 large / 50 g) | 6 g |
| Meat (1 slice / 2 oz) | 14 g |
| Seafood (2 oz) | 16 g |
| Bread (1 slice / 64 g) | 8 g |
| Corn (1 cup / 166 g) | 16 g |
| Rice (1 cup / 195 g) | 5 g |
| Dry bean (1 cup / 92 g) | 16 g |
| Nuts (1 cup / 92 g) | 20 g |
| Fruits and vegetables (1 cup) | 0–1 g |
| Pizza (1 slice / 107 g) | 12 g |
| Hamburger (medium) | 20 g |
Examples
Man, 25, 5 ft 10 in, 160 lb, light activity
Mifflin St Jeor at light activity (1.375) is 2,361 Calories/day. ADA protein is at least 73 – 131 g/day, CDC (10–35% of calories) is 58 – 202 g/day, and the WHO safe lower limit is 60 g/day.
Same person, sedentary
With activity 1.2, calories drop to 2,060. ADA tightens to 58 – 73 g/day (0.8–1.0 g/kg). CDC becomes 50 – 176 g/day. WHO stays 60 g/day because it depends only on body weight.
Metric default, 180 cm, 60 kg
The same age-25 male at light activity in metric units is ADA 60 – 108 g/day, CDC 54 – 188 g/day, and WHO 50 g/day.