What bar spacing do I need for my bird?

Across the specialist communities we read, the rough consensus is roughly 3/8 inch for budgies, parakeets, finches, and canaries; about 1/2 to 5/8 inch for cockatiels, lovebirds, and conures; and 3/4 to 1 inch for African greys, Amazons, and small cockatoos. r/parrots commenters repeatedly flag cages whose bar spacing is too wide for the listed bird, so confirm the spec before buying.