Food Portion & Comparison Calculator
Look up rounded reference nutrition for common foods, convert a typical portion into grams and macros, and compare two foods on an equal basis.
Reference lookup
Convert a common portion
Amount
Chicken breast, roasted
165 kcal
Reference amount: 100 g
Side-by-side
Compare foods on the same basis
For 100 calories
Chicken breast, roasted
61 g reference amount
100 kcal
For 100 calories
Lentils, cooked
86 g reference amount
100 kcal
Values are rounded references for common, unbranded foods. Variety, ripeness, cooking method, drainage, brand, and portion size can change nutrition. Match packaged foods to their own label and use a food scale when quantity matters.
How this tool works
Each food uses rounded per-100-gram reference values and a representative common portion. The calculator multiplies the per-100-gram values by the selected gram amount.
The comparison view can hold weight constant, hold energy constant at 100 calories, or use each food's common portion. The chosen basis changes the question, so it can legitimately change which food appears higher in a nutrient.
Food composition varies with variety, maturity, cooking, drainage, formulation, and brand. Packaged-food labels and records that match the exact preparation should take priority over a generic reference.
Sources
Frequently asked questions
Are common portions exact?
No. A medium fruit, slice, fillet, scoop, or cup can vary. The gram amount shown is a representative reference, not a measurement of the food in front of you.
Why compare foods per 100 calories?
Holding energy constant can make differences in protein, carbohydrate, fat, and food mass easier to see. It does not make one food universally better.
Should I use raw or cooked values?
Match the food you actually measured. Cooking changes water content and therefore nutrition per gram, even when it does not meaningfully change the recipe's total energy.