Free Online Protein Calculator
Calculate your daily recommended protein target based on your body weight, activity level, and fitness goals. This accurate protein calculator supports both US Imperial units and UK/EU Metric units, helping you align your dietary intake with clinical guidelines from the FDA, NHS, and EFSA.
How It Is Calculated
Daily protein recommendations are calculated by assigning a baseline multiplier corresponding to your physical activity level and adding a goal-specific adjustment. This yields a customized protein multiplier (grams per kilogram of body weight).
The baseline multipliers based on activity are:
- Sedentary: 0.8 g/kg (minimum recommended daily intake for healthy adults to prevent deficiency)
- Lightly Active: 1.2 g/kg
- Moderately Active: 1.6 g/kg
- Very Active: 2.0 g/kg
- Extra Active: 2.2 g/kg
Next, the goal-specific adjustments are applied:
- Maintenance: +0.0 g/kg (maintains current nitrogen balance)
- Muscle Building: +0.2 g/kg (provides surplus amino acids to support hypertrophy and repair)
- Fat Loss: +0.4 g/kg (higher requirements to protect lean skeletal muscle tissue from catabolism during a calorie deficit)
The final formula is:
A target range of +/-10% is also computed to give individuals a realistic daily target range. The calorie contribution of protein is calculated by multiplying grams of protein by 4 kcal/g.
Protein Synthesis, Recovery, and Safe Upper Limits
Dietary protein provides the building blocks (amino acids) necessary to repair muscle fibers micro-damaged during exercise. When muscle protein synthesis (MPS) exceeds muscle protein breakdown, muscle recovery and hypertrophy occur.
Is high protein safe? For healthy individuals with normal kidney function, scientific studies indicate that protein intakes up to 2.8 g/kg per day are safe and do not impair renal health. However, intakes exceeding this level offer little to no additional benefit for muscle retention or synthesis.
Reference Table: Daily Protein Targets by Weight and Goal
This reference table presents protein targets (in grams) for healthy adults at different weights, assuming a baseline of Moderately Active (1.6 g/kg). For US Imperial units, divide your weight in pounds (lbs) by 2.20462 to convert to UK/EU Metric units (kg) before using this tool.
| Weight | Maintenance (1.6 g/kg) | Muscle Building (1.8 g/kg) | Fat Loss (2.0 g/kg) |
|---|---|---|---|
| 50 kg | 80 g | 90 g | 100 g |
| 60 kg | 96 g | 108 g | 120 g |
| 70 kg | 112 g | 126 g | 140 g |
| 80 kg | 128 g | 144 g | 160 g |
| 90 kg | 144 g | 162 g | 180 g |
| 100 kg | 160 g | 180 g | 200 g |
Frequently Asked Questions
How is daily protein calculated by this free online protein calculator?
This accurate protein calculator takes your weight in kilograms, determines your custom protein multiplier based on your selected activity level (ranging from 0.8 g/kg for sedentary individuals to 2.2 g/kg for extra active lifestyles), applies a goal adjustment (+0.2 g/kg for muscle building or +0.4 g/kg for fat loss), and multiplies the numbers.
What is the RDA for protein according to the FDA, EFSA, and NHS?
The Recommended Dietary Allowance (RDA) established by the FDA, EFSA, and NHS is 0.8 grams of protein per kilogram of body weight (approximately 0.36 grams per pound) for a sedentary adult. This represents the minimum intake required to prevent deficiency, but active individuals and those looking to build muscle require higher intakes.
How do I convert pounds (US Imperial) to kilograms (Metric) to find my protein requirements?
Since this calculator uses metric parameters for precision, you can convert your weight in pounds to kilograms by dividing by 2.20462 (e.g., 180 lbs / 2.20462 ≈ 81.6 kg).
Can eating too much protein damage my kidneys according to health experts?
Clinical evidence reviewed by the WHO, NHS, and EFSA indicates that high protein intakes (up to 2.8 g/kg per day) do not negatively impact kidney function in healthy individuals with normal renal performance. However, people with pre-existing chronic kidney disease (CKD) should limit their protein intake as advised by their doctor.