How this protein calculator works
Your protein target depends on three things: your body size, your age, and your goal. We start with your weight. If your BMI is over 30, we use the weight you would be at a BMI of 30 instead. Body fat does not need extra protein, so this keeps your target from being too high.
Next, we multiply that weight by a range of grams per kilogram (g/kg) that fits your goal:
- Maintain weight: 0.8 to 1.2 g/kg. The low end is the RDA for adults.
- Lose fat or build muscle: 1.6 to 2.2 g/kg. Studies show this range helps you keep or build muscle.
- On a GLP-1 medication: 1.2 to 1.6 g/kg, based on a 2025 joint advisory on nutrition with these medicines.
- Healthy aging: 1.0 to 1.2 g/kg. If you are 50 or older, we never go below 1.0 g/kg for any goal.
We round your range to the nearest 5 grams and split it across your meals. Many people find it easier to hit a per-meal number than a daily total.
How we work out calories and macros
We estimate the calories your body burns at rest with the Mifflin-St Jeor equation. Then we multiply by your activity level to get your maintenance calories. For fat loss we take off 20%. For GLP-1 users we take off 15%. For muscle gain we add 10%. We never suggest fewer than 1,200 calories for women or 1,500 for men.
Your macro split starts with protein. Fat gets 30% of your calories. Carbs fill the rest. This is a simple starting point, not a strict rule.
Tips to hit your protein target
- Build each meal around a protein food, like eggs, chicken, fish, Greek yogurt, tofu, or beans.
- Spread protein across the day instead of eating most of it at dinner.
- Eating out? Many chains now list protein on their menus. Our restaurant chain guides show the best high-protein orders.
These numbers are estimates. Your needs can change with your health, training, and medicines. Use them as a starting point and adjust with help from a professional.