Yes, T8 LED bulbs can often replace T12 bulbs because they are the same length and use the same bi-pin (G13) base.

The Philips InstantFit LED replacement tube requires no re-wiring as it includes a smart electronic design that is compatible with existing electronic instant start ballasts and sockets.

Cree, Inc. is aiming to relegate fluorescent tubes to the pages of history with its new T8 series of LED tubes that promise LED-level energy savings and greatly improved light quality.