What is the legal bulb wattage for a car in Ireland?

There is no legal requirement for the wattage for most bulbs, only that they are sufficiently visible and do not blind other users.

Most headlights are 35W-55w for road use, with most other external bulbs for indicators, brakes and tail being around 5 watts.

Fog lights can be a higher power output.

The actual light produced by a car bulb of a given wattage varies depending on the technology (traditional filament, LED or HID), the reflector and the lens colour.