The label says one serving.
You ate another.

If the label serving is 30g and you ate 45g, your factor is 45 ÷ 30 = 1.5. The free serving size and portion calculator runs the same calculation and keeps the original label values beside the result.

Use numbers from one consistent column. If calories are per serving, protein, carbohydrate, and fat must also come from that same serving column. For bottles, packets, and shared dips, the sauce and dressing guide shows practical ways to get the amount used.

Worked example: 45g from a 30g serving

Suppose one 30g serving lists 150 calories, 5g protein, 18g carbohydrate, and 6g fat. You weigh the food you ate and get 45g.

• Portion factor: 45 ÷ 30 = 1.5
• Calories: 150 × 1.5 = 225
• Protein: 5 × 1.5 = 7.5g
• Carbohydrate: 18 × 1.5 = 27g
• Fat: 6 × 1.5 = 9g

The same method works when you eat less. An 18g portion from that 30g serving uses a factor of 0.6.

When pieces and grams disagree

A label might say “about 7 pieces (28g).” The pieces can vary, so seven of them may not weigh 28g. This mismatch comes up often in real-world tracking discussions about chips, bread, jerky, and other foods with uneven pieces.

If you have a scale and the label gives grams, the gram amount is the more reproducible basis. Weigh the portion, then compare it with the metric serving weight. Household measures are still useful when weighing is not practical, but they are estimates rather than identical units.

This is optional precision, not a rule for every bite. If weighing food starts to feel compulsive, stressful, or disruptive, step back and consider talking with a qualified health professional.

Eating the whole package

First check whether the label has a per-container column. Some packages show nutrition for both one serving and the whole container. If the whole-package values are present, use that column directly.

Otherwise, you can multiply one-serving values by the listed servings per container when you eat the entire package. Keep in mind that “about 2.5 servings” is itself a rounded label statement. For a measured partial package, scaling from the labeled gram serving is clearer.

Three mistakes that quietly change the answer

1. Mixing prepared and unprepared weights. Do not compare cooked pasta on the scale with a serving defined for dry pasta. Match the food state named on the label. For batches that change weight during cooking, use the raw versus cooked guide.
2. Treating per-100g values as per-serving values. If the label basis is per 100g, use the per-100g calculator instead.
3. Rebuilding calories from macros. Scale the printed calories directly. Label rounding and nutrients such as fibre or sugar alcohols can make 4/4/9 math differ.

For homemade food with several ingredients, calculate the whole batch and divide by servings or cooked weight with the recipe macro calculator.