Protein per 100g is the standard way nutrition labels and food databases express protein density. It lets you compare foods fairly regardless of how big the serving is. This calculator turns any serving size into that per-100g value instantly, then lets you rescale it to the portion you actually plan to eat.
Whether you are tracking macros, meal prepping, checking a food package, or comparing chicken breast with tofu or Greek yogurt, this tool does the math for you. Enter the serving weight you used and the protein in that serving, and the calculator returns the protein density plus the protein in any target portion — like your 180 g cooked chicken or a 50 g snack.
The result screen breaks down every step, so you can see exactly how the per-100g value was calculated. Optional fields for a target portion and a protein goal turn the result into practical portion guidance. Use it for meats, fish, dairy, legumes, nuts, or packaged products.
How to Use This Tool
Enter the weight of the food you actually measured — either in grams or ounces — and the grams of protein listed for that serving on the label, package, or nutrition database. The calculator first converts everything to a standard protein-per-100g figure, then scales it to whatever portion size you plan to eat.
- Type in the serving weight you used, then pick its unit from the dropdown (grams or ounces).
- Enter the grams of protein in that serving.
- Optional: set a target portion size (e.g., 200 g of meat) to see its protein content.
- Optional: set a protein goal (e.g., 40 g) to find out how much of the food you need.
- Press Calculate and read the main result plus the step-by-step breakdown below.
Formula Explained
The calculation is simple proportional reasoning. If a 150 g serving contains 30 g of protein, then every gram of that food contains 30 ÷ 150 = 0.2 g of protein, and 100 g contains 100 × 0.2 = 20 g. In one line:
Protein per 100g = (Protein in serving ÷ Serving weight) × 100
When the serving weight is in ounces, the calculator first converts it to grams using 1 oz = 28.3495 g, then applies the same formula. Once you have the per-100g density, scaling to a different portion is straightforward:
Protein in portion = (Protein per 100g ÷ 100) × Portion weight
You can also invert the relationship to answer the question "how much food do I need?" If you know your protein target:
Food weight needed = (Protein goal ÷ Protein per 100g) × 100
All three formulas are built into the calculator, so you get the density, the portion protein, and the goal-based food weight in a single run.
Worked Examples
Example 1: Chicken breast. You weigh a cooked chicken breast at 150 g and it contains 46.5 g of protein. Protein per 100g = (46.5 ÷ 150) × 100 = 31 g. If your planned portion is 200 g, the protein is (31 ÷ 100) × 200 = 62 g. If your daily meal target is 40 g, you would need (40 ÷ 31) × 100 ≈ 129 g of that chicken.
Example 2: Salmon in ounces. A 6 oz salmon fillet provides 34 g of protein. Convert to grams: 6 × 28.3495 = 170.1 g. Protein per 100g = (34 ÷ 170.1) × 100 ≈ 20 g. A 170 g fillet of the same fish would give about 34 g of protein, which matches the label.
Example 3: Meeting a goal with Greek yogurt. Non-fat Greek yogurt has roughly 10 g of protein per 100 g. To get 30 g of protein you would need (30 ÷ 10) × 100 = 300 g — about one large tub. Entering your goal in the optional field shows this automatically.
Common Mistakes to Avoid
Mixing up cooked and raw weights. Meat and poultry lose water as they cook, so the same piece of chicken weighs less after cooking and has a higher protein-per-100g value. Raw chicken breast is roughly 21–23 g per 100g, while cooked is closer to 31 g. Pick the weight state that matches your label entry and stay consistent.
Ignoring the unit. If your scale shows ounces but you enter grams, the per-100g result will be roughly 3.5× too high. Always confirm the unit dropdown before calculating.
Using the whole package instead of the edible portion. For foods with bones, shells, or peel, weigh only the part you actually eat. A bone-in pork chop includes bone weight, which lowers the apparent protein density if you enter the total weight.
Reference Data
Approximate protein density for common foods. Values are for cooked or ready-to-eat edible portions unless noted:
| Food | Protein per 100g |
|---|---|
| Chicken breast (cooked) | 31 g |
| Lean pork chop (cooked) | 27 g |
| Cheddar cheese | 25 g |
| Ground beef, 85% lean (cooked) | 24 g |
| Almonds | 21 g |
| Salmon (cooked) | 20 g |
| Tempeh | 20 g |
| Egg (whole, boiled) | 13 g |
| Cottage cheese | 11 g |
| Greek yogurt (plain, non-fat) | 10 g |
| Lentils (cooked) | 9 g |
| Chickpeas (cooked) | 9 g |
| Firm tofu | 8 g |
Values vary by brand, cut, and preparation method. For precise numbers, consult the USDA FoodData Central database at fdc.nal.usda.gov.
Frequently Asked Questions
Why compare protein per 100g instead of per serving? Serving sizes differ between brands, countries, and product lines. A "serving" might be 30 g for one cereal and 45 g for another. Per-100g gives a consistent baseline so any two foods can be compared fairly at a glance.
Does protein per 100g change with cooking? Yes. Cooking removes water, which concentrates protein within the same weight. For example, 100 g of raw chicken and 100 g of cooked chicken are different amounts of actual meat. Track protein using the same state as the weight you recorded.
Can I use this for packaged foods with protein listed per serving? Absolutely. Enter the serving size from the label (for example, 30 g) and the protein listed for that serving (for example, 6 g). The calculator will give you the per-100g density, which is often not printed on the package.
What about protein shakes and powders? The tool works for any food or drink. A scoop of powder is often labeled per 30 g scoop with 24 g protein — that gives about 80 g per 100g of powder. Just use the label serving weight and protein amount.