Estimate the spider harp size that fits your lamp body, shade height, and shade style. The calculator also checks proportional width and bulb clearance so the shade does not sit too high or too low.
Typical harp range6-15 inMost table lamps land here.
Best fitter typeSpiderUse a harp-mounted shade.
Rounding rule0.5 inRound to the nearest half-inch.
✨Preset lamp scenarios
Input values are converted automatically. Harp hardware is still shown in the common buying format.
🛠Measure your lamp
Measure from the table to the top of the lamp body or finial point.
Spider shades usually work best when the harp tracks the shade height closely.
Useful for empire, bell, oval, or tapered shades.
This helps check whether the shade is visually proportional.
Many spider shades have a small fitter drop that changes the harp target.
Bulb shape changes how much clearance the shade needs.
Style shifts the harp slightly up or down for a cleaner line.
Tall, narrow lamps often need a slightly different harp target than compact ones.
Choose how much of the bulb you want hidden behind the shade.
Recommended lamp shade harp setup
Enter your measurements to calculate a harp range, shade width target, and fit score.
Fit score: --
Recommended harp size
--
Estimated spider harp height.
Safe harp range
--
Nearest half-inch window.
Shade width target
--
Helps judge visual balance.
Bulb clearance
--
Clearance suggestion for the lamp style.
Calculation breakdown
Lamp profile--
Shade style--
Bulb type--
Fitter drop--
Shade height input--
Height adjustment--
Width band--
Proportion check--
📚Reference tables
Harp size by shade height
Use this as a starting point when you only know the shade height and need a fast replacement match.
Shade height
Typical harp
Best use
Note
8-9 in
6-7 in
Desk
Small shade
10-11 in
8-9 in
Bedside
Most common
12-13 in
10-11 in
Buffet
Balanced look
14-17 in
12-15 in
Tall lamp
Statement shade
Shade style adjustment guide
These offsets help the calculator keep the shade line looking natural for the style you selected.
Style
Offset
Look
Works best
Drum
+0.0 in
Even
Modern lamps
Empire
+0.5 in
Tapered
Classic bases
Bell
+0.5 in
Soft curve
Traditional rooms
Rectangle
+0.3 in
Architectural
Corner tables
Bulb clearance guide
Clearance is a practical check, not a hard rule. The lamp should stay cool, covered, and visually centered.
Bulb type
Clearance
Note
Use when
LED compact
0.5-1 in
Low heat
Small shades
Standard A19
0.75-1.25 in
Common fit
Bedside lamps
Globe
1-1.5 in
Wider bulb
Open shades
Decorative
1.25-2 in
Visible bulb
Statement lamps
Fitter compatibility guide
Harps are for spider shades. If your shade uses a different fitter, the calculator will still explain the result clearly.
Fitter
Uses harp?
Hardware
Note
Spider
Yes
Harp + finial
Standard choice
Uno
No
Socket ring
Harps not used
Clip-on
No
Bulb clip
Tiny shade
Euro uno
No
Euro ring
Special mount
Tip box 1
For replacement shades, the quickest check is shade height first, then harp height, then width balance.
Measure the existing shade if you already have one.
Round to the nearest half-inch for a cleaner hardware match.
Keep spider shades centered over the bulb.
Tip box 2
If the shade is a little taller or wider than expected, use the next harp size up so the finial can still seat cleanly.
Shallow shades may need a shorter harp.
Tall empire and bell shades often need more clearance.
Clip-on and uno shades do not use this hardware.
This calculator estimates a practical spider-harp size using shade height, lamp proportions, and fitter drop. For very unusual lamp bodies, specialty shades, or antique hardware, compare the result with the shade spec sheet before ordering replacement parts.
Most lamps use a harp to hold the shade. Those lamps, that have a harp or 3/8″ diameter holder, use harp lamp shades. The harp sets the shade to the lamp and you can remove it easily.
Lamps come in many sizes, shapes and materials, so it matters to choose the right size of harp
How to Choose the Right Harp and Lamp Shade
Harps are available in a wide range of sizes, usually from 4 to 15 inches, with half-inch steps. Brass lamp harps come in half-inch and full-inch steps from 6 to 15 inches. The measure shows the whole length of the harp together with the screw on top.
Brass harps come with nickel or brass cover and in sizes of 4″ to 15″. Heavy harps, also covered with nickel or brass, come in 5.5″ to 15″.
To ensure a good fit of the shade, you need the right size of harp. You measure harps in inches from the bottom edge to the top. Practical advice is to choose a harp that puts the bottom of the shade so it covers only the port and bulb.
The shade itself decides the harp size. You measure it commonly from the ring to the bottom. A higher lamp can use a shorter harp to hide the port.
A short harp puts the shade lower on the lamp, while a long harp raises it higher. When the shade sits too high, a shorter harp solvs the problem.
To find the right harp size, you put the shade at a good height and measure between the top donut in the center of the shade and the bottom of the edge. Usually the whole height of the shade should not be more than the harp height plus half an inch, nor be less than harp height minus half an inch.
When you hesitate between two sizes, it is better to choose the bigger. Even so, very slim and high lamps commonly use smaller shades. The size of the lamp base also affects the shade and harp size.
About shade size, the width should double the base size, and the height be around a third.
To measure a shade well, check three main parts: the top diameter across the top opening, the bottom diameter across the bottom opening and the slant height from the top edge to the bottom edge. Between the bulb and the shade fabric should stay at least 2 to 3 inches of space, so that heat does no harm it, especially with non-LED bulbs.
IKEA shades use integrated rings that sit directly on the port, not harps. This does not match standard American lamps. Adapter rings are little inserts that narrow or widen the hole in the fitter of the shade, so you can use IKEA shades on non-IKEA lampbases.
