Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
43,000
feathers
How to estimate it
Fermi’s official “Napkin math”
Picture plucking a chicken. How many feathers come off? Thousands, call it 10,000. The bird weighs about 5 pounds and the feathers are a small slice of that, maybe a twentieth, so a quarter pound.
- Feathers on one chicken
- ≈ 10,000
- Their weight, 1/20 of a 5 lb bird
- ≈ 1/4 lb
- 1 lb is 4 birds' worth
- × 4
- 10,000 × 4
- ≈ 40,000
Picture plucking a chicken. How many feathers come off? Thousands, call it 10,000. The bird weighs about 2 kilograms and the feathers are a small slice of that, maybe a twentieth, so 100 grams.
- Feathers on one chicken
- ≈ 10,000
- Their weight, 1/20 of a 2 kg bird
- ≈ 100 g
- 450 g is 4.5 birds' worth
- × 4.5
- 10,000 × 4.5
- ≈ 45,000
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Cobb-Vantress: 9,000 feathers weigh 74 g on a 5 lb (2.3 kg) broiler
- ≈ 55,000 per lb
- Feedipedia: feathers are 3 to 7% of body weight, 6,000 to 10,000 per bird
- ≈ 32,000 per lb
- Middle of the two sources
- ≈ 43,000
Reference cited by Fermi: Cobb-Vantress broiler feather data (about 9,000 feathers weighing 74 g) and Feedipedia (FAO/INRAE), feathers as 3 to 7% of a chicken's body weight
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.