How many watts does a light bulb use?

Answer #1:
Anywhere from 1 (power saver) to 200 (filament/halogen).
Answer #2:
It depends on the bulb and its rating. Household incandescent bulbs go
from 2 watts to 200 watts depending on the design and materials used.
Answer #3:
-- Incandescent bulbs are available ranging from 1.19 watts (PR2 flashlight bulb)
to 700 watts (aircraft obstructon lighting beacon).

-- LEDs start at about 0.02 watts.

-- Halogen reflector lamps using 5,000 watts are in regular commercial production.

-- Around 1932, General Electric built a small quantity of 50,000-watt incandescent
bulbs ... enough to establish that they could work, could deliver a reasonable lifetime,
and could be shipped from place to place without breaking.