Vegetable Serving Calculator

One cup of vegetables sounds like a standard serving, but the weight varies enormously. A cup of spinach is 30 grams — barely an ounce. A cup of tomato is 180 grams. The volume is identical; the food is not.

This matters for meal planning because recipes give cups while nutrition databases list grams.

Why the weights differ so much

Texture and density. Raw spinach is mostly air pockets. Carrots are solid and dense. Corn kernels pack tightly. Sweet potato cubes settle. One cup of kale is a loose pile of leaves; one cup of peas is a fairly tight fill.

For practical cooking, 1 cup per person is a reasonable portion for most non-starchy vegetables. Corn, peas, and sweet potato are exceptions — they are calorie-dense and a half-cup is often more appropriate.

Calories per serving

Leafy greens and watery vegetables are very low: spinach (7 kcal/cup), zucchini (19 kcal/cup), cucumber (16 kcal/cup). You can eat large volumes without much caloric impact.

Starchy vegetables are different: corn (132 kcal/cup), peas (117 kcal/cup), sweet potato (114 kcal/cup). These are nutritionally valuable but need to be counted if you are tracking intake.

Meal planning rule of thumb

For side dishes, 1 cup raw per person is the default, dropping to half a cup for the starchy three (corn, peas, sweet potato) and rising to 1.5 or 2 cups when the vegetable is the main event in a bowl or salad. The portion dropdown above covers all of those, so pick the one that matches the plate you are building rather than mentally multiplying afterwards.

The other thing volume charts leave out: shrinkage

Buy a cup of spinach and you will not serve a cup of spinach. Leafy greens are mostly air and water held in a loose structure, and heat destroys that structure almost immediately. Spinach comes down to something like 15% of its raw volume, kale to 25%. A pan that looks absurdly overfull when you start is exactly right by the time it wilts.

Denser vegetables barely move. Corn and peas hold their volume completely, carrots lose a little water, and zucchini sits in the middle at about a third lost. The calculator does this arithmetic for whichever vegetable you pick, and for the collapsing ones it tells you what to buy rather than what to serve.

The calorie numbers here are all raw. Roasting changes them, and not by a small amount: oil is 120 kcal per tablespoon, so a tray of broccoli that started at 31 kcal a cup lands nearer 80 by the time it comes out browned and glossy.