Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
109,586
hydrants
How to estimate it
Fermi’s official “Napkin math”
New York has roughly 6,000 miles of streets. How far apart are the hydrants? You pass one about every block, so call it every 300 feet, which works out to about 18 per mile.
- Miles of NYC street
- ≈ 6,000
- Hydrant every 300 feet
- ≈ 18 per mile
- 6,000 × 18
- ≈ 108,000
New York has roughly 10,000 kilometers of streets. How far apart are the hydrants? You pass one about every block, so call it every 100 meters, which is 10 per kilometer.
- Kilometers of NYC street
- ≈ 10,000
- Hydrant every 100 meters
- 10 per km
- 10,000 × 10
- ≈ 100,000
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- NYC Comptroller audit of DEP hydrants (2019)
- 109,586
- NYC Open Data citywide hydrant records
- 109,725
- ≈
- 110,000
Reference cited by Fermi: NYC Department of Environmental Protection citywide hydrant records via NYC Open Data
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