All Fermi answers
Fermi #24 · Question 1

How many grains of basmati rice fit in a 500 ml (16.9 oz) water bottle?

Explore the official answer and the simple reasoning behind this Fermi estimate.

1QUESTION 1 OF 3

Answer & explanation

The official answer, with Fermi’s reasoning step by step.

Answer & explanation

Official answer

20,000

grains

How to estimate it

Fermi’s official “Napkin math”

Picture a level teaspoon of dry rice, a common kitchen measure. Maybe 150 grains fit on it. A teaspoon is about 5 milliliters, so a 500 milliliter bottle holds about 100 teaspoons.

Rice on one teaspoon (5 ml)
≈ 150 grains
Teaspoons in 500 ml
≈ 100
150 × 100
≈ 15,000

Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.

Source calculation & reference
USDA: 1 cup (240 ml) uncooked white rice
≈ 185 g
Average grain weight
≈ 0.02 g
185 ÷ 0.02
≈ 9,250 grains per cup
Scaled to a 500 ml bottle
≈ 20,000 grains

Reference cited by Fermi: USDA FoodData Central (uncooked white rice, cup measure)

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