Popcorn Calculator (kernels to pop for your guests: cups, grams, tablespoons)

Understanding the popcorn calculator — concept and principle

This calculator works out how many unpopped kernels to use for a group, and how many batches your pot or popper needs, from the number of people and how much popped popcorn each one eats. It is handy for movie nights, parties and school events.

2 tablespoons pop 1 quart: with the default inputs the result is 1 cup kernels (≈ 227 g · 2 batches).

How it is calculated

Popped popcorn (quarts) = people × cups per person ÷ 4.
Kernels: 2 tablespoons (⅛ cup, about 1 oz or 28 g) make 1 quart popped.
Kernels in cups = quarts ÷ 8; in tablespoons = quarts × 2; in ounces = quarts; in grams = quarts × 28.35.
Popped litres = quarts × 0.946.
Batches = kernel cups ÷ cups per batch, rounded up.

The principle

Each popcorn kernel holds a little water inside a hard hull. Heated to around 180 °C, the water turns to steam, the pressure bursts the hull and the starch puffs into foam. That expansion is why a small amount of kernels makes a large volume of popcorn. The Popcorn Board's rule of thumb is that 2 tablespoons of kernels make about 1 quart (4 cups) popped, so half a cup makes about 4 quarts.

Worked example

Default inputs: 8 people, 4 cups each, ½ cup of kernels per batch.

Popped = 8 × 4 ÷ 4 = 8 quarts = 7.6 L.
Kernels = 8 ÷ 8 = 1 cup = 16 tablespoons = 8 oz = 8 × 28.35 = 227 g.
Batches = 1 ÷ 0.5 = 2.

Each point is the calculator re-run with only “People” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

People	Unpopped kernels (cups)
2	0.25
4	0.5
6	0.75
8	1
10	1.25
12	1.5
16	2

How to read the result

Old or dry kernels pop less and leave more unpopped, so buy a little extra. Popped volume varies with the variety (butterfly or mushroom) and popping method. For kids or as a side snack, fewer cups per person may be enough.

Common mistakes

Overfilling the pot, which leaves many kernels unpopped.
Measuring popped and unpopped cups the same way.
Storing kernels in the fridge, which can dry them out.
Forgetting oil, butter and seasoning in the shopping list.

Keep in mind: Hot oil and steam can burn; keep a lid on while popping. Popcorn can be a choking hazard for young children.

Frequently asked questions

How many kernels make a bowl of popcorn?

2 tablespoons make about 4 cups popped.

How much popcorn for 8 people?

About 1 cup of kernels for 4 cups popped each.

How much does ½ cup of kernels make?

About 4 quarts (16 cups) popped.

Sources: The Popcorn Board, "Unpopped to Popped" · NIST Handbook 44, Appendix C (1 oz = 28.349523125 g; 1 US quart = 0.946352946 L)

Checked 9 Nov 2026. The Popcorn Board, “Unpopped to Popped” (1 oz, ⅛ cup or 2 tablespoons of kernels yield 1 quart popped; ½ cup yields 4 quarts). 1 oz = 28.349523125 g, 1 US quart = 0.946352946 L (exact). Serving size and batch size are example values.

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