Size of T12 Bulbs

T12 bulbs are among the most commonly used fluorescent lights.

The designations that identify fluorescent bulbs can be confusing. The bulb type may look like a random group of letters and numbers but it's actually a simple categorization of the wattage, size and shape of the bulb.

Shape

The letter T in "T12 bulb" stands for "tubular" and indicates the shape of the light bulb. Most people are familiar with fluorescent light tubes but it's important to specify the shape because fluorescent lights are also available in other shapes. Circular, U-shaped, and other fluorescent models do not have the letter T in their names.

Width

In "T12 bulb," the number 12 is used to identify the diameter of the bulb. This number shows how many eighths of an inch wide the bulb is, making the T12 bulb 1 1/2 inches wide. T5 and T8 are also common widths for fluorescent tubes.

Length

The length of a fluorescent bulb is not expressed in this designation. According to the website eLightBulbs, fluorescent lights can measure from 15 inches to 12 feet long.

References

• ELightBulbs.com: T12 Fluorescent Lighting