How big should the light be over a vanity mirror?

How Do I Figure Out What Size Vanity Light I Need? Every bathroom is different, so the size of the vanity light needed varies. An easy rule to remember is to pick a lighting fixture that's around three-quarters of your vanity's width. You'll want to centre the light above the mirror.

Is it better to have bathroom vanity lights facing up or down?

Bright task lighting: Downward-facing lights provide the bright, direct light ideal for grooming tasks such as applying makeup and shaving. Reduced shadowing: With downward-facing lights, there is less shadowing around the face and under the chin, making it easier to see while performing grooming tasks.