Bulb Guide

Home » Bulb Guide

How to find your Light Bulb

Find your bulb guide

We have listed approximately 1200 of the most commonly used light bulbs.

For most bulbs you may select the initial category by name, General Incandescent, Fluorescent, Compact Fluorescent, HID, Halogen or Exit Signs and Specialty Bulbs or you may also choose by clicking on the pictures provided.

Be sure to read the notes to prevent choosing a similar looking bulb that has different characteristics.

Choose a Category

You start with the general category and progress to the specific bulb you want. First find the correct category. Use the pictures to help determine where you want to start. To clarify the difference between similar looking bulbs we offer the following explanations.

Reflector bulbs – Similar in shape to some halogen bulbs.

  1. Glass lens has smooth appearance.
  2. Lightweight construction when compared to halogen.
  3. Softer lighting effect than halogen.

Halogen – Similar in shape to some reflector bulbs.

  1. Glass lens has a textured or bumpy look to it.
  2. Heavier construction than a reflector bulb.
  3. More lighting punch.

Compact fluorescent – Some can be used as direct replacement for many incandescent, halogen and reflector bulbs. Some retrofits come as a complete individual system. It contains an aluminized glass reflector, a ballast adapter and a replaceable fluorescent lamp.

Pre-assembled units simply screw into any standard incandescent socket. They provide fantastic energy, labor and lamp replacement savings. The only concern here is space. Lampshades or other clearance considerations need to be compared to length and shapes of these bulbs.

Self-ballasted Mercury Vapor – Direct replacement for incandescent. Again the concern here is space and size of screw base.

Bulb Shape and Size

Next determine the size and shape of the bulb you want.

Overall length is listed as M.O.L.

Diameter is measured at the lenses largest point. It is expressed in one eights (1/8″) of an inch. We have converted these improper fractions to proper fractions. i.e. A standard household bulb is an A-19, that is 19/8″ or 2 3/8″ in diameter. An A-21, which is slightly larger, is the same shape and 21/8″ or 2 5/8″ in diameter. These dimensions are listed for each individual bulb.


Next you must choose the base. Simply put, that’s the part that fits in the socket. Sizes of screw in bases are difficult to distinguish between on a computer’s monitor so we offer the following descriptions in an effort to be clear. They are listed from smallest to largest.

minican = mini-candelabra

cand = candelabra

inter = intermediate

med = medium (standard household)

mog = mogul

Most other bases are unique and can be visually identified by shape or number of pins protruding.

Final Selection

Once you have determined the bulb category, shape and base, you will choose from a list that will match your selection criteria. Be sure to be particular in the final details. Is the bulb frosted, clear, a spot light or flood? Is it the correct color temperature, day light, cool light, etc.?


If you do not find the bulb you want or are not sure e-mail us or call during normal business hours 1-877-WHATWAT. 1-877-942-8928. We’ll be glad to help.

Contact Us

"*" indicates required fields

This field is for validation purposes and should be left unchanged.