Serving Size Comparison Calculator

Serving sizes are set by manufacturers and vary widely between brands — a 40g serving and a 55g serving are impossible to compare directly. Normalizing to per 100g levels the playing field so you can see which food is truly more calorie-dense or protein-rich, regardless of how the serving was defined.

Check the Nutrition Facts label on the product packaging — it lists the serving size in grams along with calories, protein, carbohydrates, and fat per serving. For restaurant foods, the information is often available on the restaurant's website or nutrition guide. USDA FoodData Central is also a free resource for thousands of foods.

General guidelines suggest men typically need 2,000–2,500 kcal per day and women 1,600–2,000 kcal, meaning men's individual portion sizes are often 20–30% larger. However, activity level, age, and health goals matter more than gender alone. Use this calculator alongside your total daily calorie target to size portions appropriately.

Use the 'Number of Servings to Compare' field to scale both foods up simultaneously. As a general rule for parties, plan for 1–1.5 main-dish servings per adult and 0.5–0.75 servings per child. It's always safer to prepare slightly more than you think you'll need to avoid running short.

Calorie density is the number of calories per gram (or per 100g) of food. Foods with low calorie density — like vegetables and broth-based soups — let you eat a larger volume for fewer calories, which supports satiety. Comparing calorie density per 100g helps you choose foods that keep you full without overshooting your calorie budget.

Most nutrition guidelines recommend 0.8g of protein per kilogram of body weight per day for sedentary adults, rising to 1.2–2.0g/kg for active individuals. A single serving containing 15–30g of protein is generally considered a high-protein serving. Use the protein-per-100g comparison to spot which food gives you more protein per gram eaten.

Yes — many restaurants publish nutrition data online or on their menus. Simply enter the serving weight in grams and the calorie/macro figures for each menu item into Food A and Food B fields. If a restaurant only lists ounces, multiply by 28.35 to convert to grams.

Store leftovers in airtight containers within two hours of cooking and refrigerate for up to 3–4 days, or freeze for up to 3 months. Labelling containers with the date helps track freshness. Planning portion sizes accurately before cooking — using tools like this calculator — is the best way to reduce leftovers in the first place.