Market-Sizing Estimate: Total Windows on New York City's Buildings

Estimate the number of windows in New York City. Talk through your approach as you would in an interview: how you break the problem down, the assumption behind each number and the arithmetic. Finish with one figure, a plausible range and a quick check that the result makes sense. ```hint Anchor on what you can count Windows belong to buildings, and buildings exist to house people and the places where they work, study and shop. Start from a quantity you can estimate with some confidence, then decide how many windows each unit of it brings. ``` ### Clarifying Questions - Do only windows in buildings count, or also those in cars, buses and subway cars? - How is one window counted: is a glass curtain wall on an office tower one window per framed panel, and does a window with two sashes count once? - Does New York City mean all five boroughs, or only Manhattan? - Do storefront display windows, skylights and interior glass partitions count? ### What a Strong Answer Covers - A clear definition of what counts as one window and which area the count covers - A segmentation of buildings (apartments, houses, offices, shops, schools and other institutions) that reflects how window counts actually differ between them - Labeled, round-number assumptions and arithmetic that an interviewer can follow and check - A final figure with a range and an independent sanity check - Awareness of which assumptions move the total most ### Follow-up Questions - Which single assumption changes your total the most, and how would you narrow it down? - If a window-cleaning company wanted to use your number to size its market, what would you change in the estimate? - With access to real data such as city building records or street-level imagery, how would you check your answer?