Quant interview prep guides

Fermi Estimation Benchmark Numbers

Fermi estimation benchmark numbers for rough population, time, usage, money, and scale assumptions in interview estimates.

Candidates who need reference scales without inventing facts.

Benchmarks are starting points

Fermi benchmarks help with scale, but they are not verified current data. State them as rough assumptions unless the prompt gives exact facts.

Useful categories

Population scale, days per year, hours per day, usage frequency, average price, and order-of-magnitude money values are common categories.

Concrete example

Using about 365 days per year is a benchmark. Rounding to 350 or 400 can be fine when the rest of the estimate is rough.

Check against bounds

A benchmark should help a sanity check. If the final answer violates a simple upper bound, revise the assumption or unit.

Common mistakes

Candidates often present remembered numbers as facts. In interviews, transparent roughness is safer than fake precision.

Practice the pattern

Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.