How-to · Updated October 2, 2026
What size lamp shade do I need?
Direct answer
Make the bottom diameter about equal to the base height (within 2 inches) and the shade height about two-thirds of that base. An 18-inch base takes 11 × 18 × 12.5 as an empire shade, or 18 × 18 × 12 as a drum, with an 11.5″ harp.
Sizes to shop for
Base height is bottom of the base to bottom of the socket. Listings are top × bottom × slant, in inches.
| Base to socket | Bottom diameter | Empire | Drum | Harp |
|---|---|---|---|---|
| 12 in | 10–14 in | 7 × 12 × 8.5 | 12 × 12 × 8 | 7.5″ |
| 16 in | 14–18 in | 10 × 16 × 11.5 | 16 × 16 × 11 | 10.5″ |
| 18 in | 16–20 in | 11 × 18 × 12.5 | 18 × 18 × 12 | 11.5″ |
| 24 in | 22–26 in | 14 × 24 × 17 | 24 × 24 × 16 | 15.5″ |
How the 18-inch shade is built
- Bottom diameter ≈ base height = 18 in (good range 16 in–20 in)
- Widest part of base 7 in + ½″ each side = at least 8 in
- Shade height ≈ ⅔ × 18 in = 12 in (±1″)
- Empire (classic taper): top ≈ 0.6 × 18 in = 10.8 in
Limits
- These are retailer proportion rules, not a single industry standard. A shade you already like can be copied by measuring it.
- If the number you have is the whole lamp including the shade, it is larger than the base-to-socket height. The shade is about 40% of that finished height.
- Small lamps often use a clip-on or uno fitter. A spider fitter needs the harp.
Use the calculator
Reading a listing: what 9 × 16 × 10 means. Enter a base in the lamp shade size calculator.