All Fermi answers
Fermi #99 · Question 1

How many 8 oz (240 ml) cups of coffee can you brew from one arabica coffee tree's yearly harvest?

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

1QUESTION 1 OF 3

Answer & explanation

Using 0.5 oz (14 g) of ground coffee per cup.

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

Answer & explanation

Official answer

32

cups

How to estimate it

Fermi’s official “Napkin math”

A coffee tree is a big bush covered in red cherries. How many? Maybe 2,000, with 2 beans inside each. How many beans make one cup? A small handful, call it 100.

Cherries on a tree
~2,000
Beans per cherry
× 2
Beans per cup
÷ 100
2,000 × 2 ÷ 100
≈ 40

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

Source calculation & reference
One coffee tree's yearly harvest, roasted (Starbucks)
≈ 1 lb (454 g)
Ground coffee per 8 oz (240 ml) cup
÷ 14 g
454 ÷ 14
≈ 32

Reference cited by Fermi: Starbucks Coffee Blog, 'Roast Story': each coffee tree produces the equivalent of about a pound of roasted beans per year · Specialty Coffee Association Golden Cup standard: 55 g of coffee per liter of water, about 12 to 14.5 g for an 8 oz (240 ml) cup

How close was your guess?

Your comparison will appear here.

Compare by ratio: divide the larger number by the smaller one. The closer to 1×, the better.

Skip to main content