Like bulbs in the A group, their most common base types are the E26 and E27 medium screw in bases, the E12 candelabra base, as well as the E17 base. Bulbs in the R and BR group include reflectors and bulged reflectors, respectively.

Find the light bulb base type you’re looking for with this visual chart- detailed illustrations of general bases, fluorescent bases and specialty halogen base types.

“A” type bulb shapes are standard types for household lighting but you will see different variations and types of them. However, the standard bulb sizes are A19 and A60. The letter indicates the shape of the bulb but the number following it is the diameter of the bulb in eighths of an inch.

Most type A bulbs have a pear-like, circular shape. They look exactly like what comes to your mind when you think of a “light bulb.” They typically have an E26 or an E27 base. You can also find the type of bulb on its package. If you find the letter “A,” followed by two digits, that’s a type A bulb. How Long Do Type A Light Bulbs Last?

Here are the most common light bulb base types and sizes: A (Arbitrary): Represents similar to a standard household bulb. These bulbs are used in chandeliers and kitchens as focused lighting for meal preparation or cooking. C (Conic): Similar to a traditional Christmas tree bulb, these bases are best for task and decorative lighting.