How to Measure a Lamp Shade

Tags: Lamp Shades | By: Shades of Light | Date: 03-05-2024 (update)

Determining what size lampshade you need for your table or floor lamp doesn’t have to be complicated but it does require a little know-how when it comes to lampshade dimensions and how those measurements are determined. Not sure how to know what size lampshade to buy? We have pulled together a few guidelines to help answer your questions, including one we hear a lot: How do you measure a lampshade?

Lampshade Measurement Guidelines

Lamp shade measurements are listed with three main dimensions: Top x Bottom x Side. If a lamp shade is round or square, one number will be listed for each of these dimensions. Rectangular or oval shades will typically have both the length and width listed for both the top and bottom dimensions. Use the following method to measure your lamp shade.

Top: For round or square shades, measure across the top of the shade. For rectangular or oval shades, measure both the length and the width of the shade.
Bottom: Repeat this process for the bottom of the shade.
Side: Measure along the side of the lamp shade, following the slant if the top is slimmer than the bottom.
Height: Measure from the top of the shade straight down, rather than following the slant.

If you are looking to replace an existing shade, first measure the height and slant of you shade. Tip: consider that lamp shades with steep slants have a longer ‘side’ measurement than ‘height.’ Once you’ve recorded these lamp shade dimensions, shopping for your replacement shade will be a breeze!

What Height Lampshade Do I Need?

If your lamp does not have a shade to use as reference, a good general rule to follow for sizing lampshade height is to measure the lamp itself from the base to the bottom of the socket; choose a shade roughly two-thirds that number for table lamps, and one-fourth that number for floor lamps. To determine a range of heights to search within, multiply the height of your lamp by 60% to 70% for table lamps, and 25% to 40% for floor lamps. If only three dimensions are provided for your prospective lampshade, use the ‘side’ measurement in place of height—the ‘side’ and ‘height’ of the shade will be identical in shades with no taper, and fairly similar in tapered shades unless it has a particularly steep slant.

Let’s test these formulas!

Our Flagon Table Lamp is about 16.5” high from the base to the bottom of the socket. Find two-thirds of the height of the lamp by multiplying that number by .66 for example: 16.5 x 0.66 = 10.89. To find a range, multiply the height by 60% and 70%. For example: (16.5 x .6=9.9) and (16.5 x .7=11.5) This lamp can take shades between 9.9” and 11.5” high. The Flagon Table Lamp comes with an 11” shade, which is a perfect match for this fixture!

We can use the same method for floor lamps, but multiply by .25 to determine one-fourth the height of the lamp. Our Country Club Adjustable Floor Lamp has a height of roughly 35” (Example: 35 x 0.25 = 8.75) To find a range, multiply by 25% and 40% (Example: 35 x 0.25 = 8.75 and 35 x 0.4 = 14).

This lamp can take shades between 8.75” and 14” high. The Country Club Adjustable Floor Lamp comes with a shade that is 10.5” high—right within the suggested range for this fixture!

Keep in mind, an inch or so in either direction can still work if the shade you’ve fallen in love with is just outside the suggested range. If you’re torn between two shades, go with the larger one.

What Width or Diameter Should My Lamp Shade Be?

Lampshade size is usually expressed in terms of the bottom diameter— a 16" shade has a base that is 16” wide—so this number will be essential for refining your lampshade search. There are two recommended ways to find the ideal lampshade diameter for your lamp.

To use the height of the lamp to find the perfect shade diameter, simply find a shade with a diameter within two inches of the height of the lamp. A lamp that is ten inches high can take a shade that is between eight to twelve inches wide.