How to Measure a Table Lamp Shade

To measure a table lamp shade, take four measurements in centimetres: the diameter across the top opening, the diameter across the bottom opening, the vertical height from top to bottom, and, for tapered shades, the slant length along the side. Then check the fitting: most UK table lamps use a ring that drops over the bulb holder, while others use a spider fitting that sits on a harp, or a clip that attaches to the bulb itself. With those details you can replace a shade confidently or choose one that suits a new base.

Shades are often an afterthought, yet they shape the whole character of a lamp and decide how much light reaches the room. If you would rather start with a complete design, our range of modern table lamps UK pairs bases and shades that are already balanced. For everything else, this guide will help.

What You Will Need

You only need a few simple things: a flexible tape measure or a rigid ruler, a pencil and a notepad, and a flat surface to rest the shade on. A metal retractable tape is useful for straight measurements, while a soft dressmaker’s tape is easier for slant lengths on curved shades.

Always switch off and unplug the lamp before removing the shade, and let the bulb cool fully if the lamp has been on. Measuring is a good moment to think about the lighting in the room as a whole, and our wider lighting UK sale collection is a useful reference if you are planning more than one lamp.

Step One: Measure the Top Diameter

Place the shade upright on a flat surface. Lay your tape measure across the top opening, passing through the centre, and measure from one outer edge to the opposite outer edge. Make sure the tape crosses the widest point rather than a shorter chord near the edge.

For square or rectangular shades, measure the length and width of the top separately. For oval shades, measure both the longest and the shortest distances across.

Step Two: Measure the Bottom Diameter

Turn the shade over, or measure across the bottom opening while it rests on its side. Again, go from outer edge to outer edge through the centre. The bottom diameter is usually the measurement retailers list first, because it has the biggest effect on how the shade looks in proportion to the base.

Step Three: Measure the Height

Height means the vertical distance between the top and bottom rims, not the length down the side. Stand the shade upright and hold a ruler straight up beside it, or rest a book flat on top and measure from the surface to the underside of the book. This gives a true vertical height even if the sides are angled.

Step Four: Measure the Slant

The slant, sometimes called the side length, is the distance along the outside of the shade from the top rim to the bottom rim. On a straight sided drum, slant and height are the same. On a tapered empire or coolie shade, the slant is longer than the height.

Slant matters most when you are ordering a replacement fabric cover or comparing shades from different makers, since some list slant rather than height.

Step Five: Identify the Fitting

The fitting is how the shade attaches to the lamp, and it is just as important as the size. A beautiful shade with the wrong fitting simply will not sit properly.

Ring fitting

This is the most common type in British homes. A metal ring sits in the centre of the shade frame, held by struts, and drops over the bulb holder before the bulb or a threaded collar holds it in place. Rings come in different sizes to suit bayonet and screw holders, and many shades are supplied with a reducer ring so they fit more than one type. Measure the inner diameter of the ring, or check the size of your lamp holder, before you choose.

Spider fitting

A spider fitting has a small central washer at the top of the shade, connected to the rim by spokes. It sits on top of a harp, a metal hoop that rises around the bulb, and is fixed with a small finial. If your lamp has a harp, the height of the harp influences how high the shade sits.

Clip fitting

Clip shades attach directly to the bulb with a wire clip. They are usually small and used on candle style bulbs in chandeliers and wall lights, as well as on some compact table lamps.

Proportion Guidelines for Choosing a New Shade

Once you have the numbers, you can judge whether a shade suits its base. These are guidelines rather than strict rules, but they work for most lamps.

• Height. The shade is usually around two thirds of the height of the base, measured from the bottom of the base to the bulb holder. Much taller and the lamp looks top heavy. Much shorter and it looks like it is wearing a hat that is too small.
• Width. The bottom diameter generally works well at roughly twice the width of the widest part of the base. On slim column bases you can go a little wider for balance.
• Coverage. When you are seated or standing near the lamp, the bottom of the shade should hide the bulb holder and any harp. If you can see hardware below the rim, the shade is sitting too high or is too short.
• Shape echo. Rounded bases such as gourds and ginger jars look natural with round drum or empire shades. Square or angular bases often look sharper with square or rectangular shades.

Shade Shapes and How They Affect Light

The shape of the shade changes how light falls. A drum shade, with similar top and bottom diameters, sends light both up and down in roughly equal amounts and gives a modern, even glow. An empire shade, narrower at the top and wider at the bottom, directs more light downwards onto the table, which suits reading lamps. A coolie shade, with a very narrow top and a wide flared bottom, throws a broad pool of light below and very little above. A bell shade, with gently curved sides, gives a traditional and softly diffused effect.

Material matters too. Linen and cotton diffuse light warmly. Paper and parchment give a crisp glow. Dark or lined shades push most of the light up and down, creating a moodier effect with less spill into the room.

Measuring the Space Around the Lamp

A shade that suits its base can still feel wrong if it does not suit the furniture beneath it. Before buying, measure the surface the lamp will sit on and the space around it.

On a bedside table, the bottom of the shade should sit roughly at eye level when you are sitting up in bed, so you get light on your book without seeing the bare bulb. The shade should also be narrower than the table top so it does not overhang and get knocked. If you are choosing new bedroom pieces, our modern bedside cabinets UK range includes a variety of heights and top sizes to suit different lamps.

In a living room, a lamp on a side table beside a sofa looks best when the bottom of the shade sits at about the height of a seated person’s shoulder. Our high gloss lamp tables UK collection offers compact surfaces designed to hold a lamp alongside a drink or a book.

For more detail on bedroom proportions, our guide to bedside table measurements for UK bedrooms explains how table height relates to mattress height, and our explainer on lamp tables and side tables in UK homes clarifies which table suits which spot.

Common Measuring Mistakes to Avoid

• Measuring the slant instead of the height. On tapered shades this can make a shade seem several centimetres taller than it really is.
• Measuring inside the rim. Always measure the outer edges for diameters, as listed sizes are external.
• Forgetting the fitting. Size is only half the story. Note the fitting type and ring size every time.
• Ignoring the bulb. Make sure there is enough space between the bulb and the fabric. Check the maximum wattage marked on the lamp and choose an LED bulb, which runs much cooler than older types.
• Rounding too generously. A centimetre or two can change proportions noticeably on a small lamp, so note exact figures.

A Quick Measuring Checklist

Before you shop, make sure you have written down the top diameter, the bottom diameter, the vertical height, the slant length if the shade is tapered, the fitting type and ring size, the height of the base to the bulb holder, and the dimensions of the table the lamp will sit on. With that list, you can compare shades with confidence and avoid disappointment.

At Furniture in Fashion we list clear dimensions for our lamps and furniture, so you can measure once and choose pieces that work together in your room.

Frequently Asked Questions

Which measurement is most important for a lamp shade?

The bottom diameter usually has the biggest effect on proportion, but you also need the height and the fitting type to be sure a shade will suit your base and attach properly.

How big should a lamp shade be compared to the base?

As a guide, the shade height is around two thirds of the base height, and the bottom diameter is about twice the width of the widest part of the base.

What is the difference between height and slant on a lamp shade?

Height is the straight vertical distance between the rims. Slant is the length measured along the side. On straight drum shades they are equal, but on tapered shades the slant is longer.

How do I know which fitting my lamp needs?

Look at how the current shade attaches. A ring that drops over the bulb holder is a ring fitting, a shade that sits on a metal hoop is a spider fitting, and a shade that grips the bulb is a clip fitting.