A flush ceiling light sits against the ceiling. A semi flush hangs a little below it on a short stem. That is the whole definition, and on its own it will not stop you buying the wrong one.
The useful question is not which name a fitting goes by. It is how far down it comes, because that number decides whether anyone walks into it. On the fittings below, semi flush covers everything from 231mm to 480mm. The deepest is more than twice the shallowest, so read the measurement and ignore the word.
The short version
- Flush means against the ceiling, semi flush means on a short stem below it
- Projection, the figure from ceiling to the bottom of the fitting, is what you actually need
- Semi flush fittings here run from 231mm to 480mm, so the name settles nothing
- Our planning figure is 2.1 metres of clear headroom where people walk beneath a light
- On a standard 2.4 metre ceiling that leaves you about 300mm of fitting
The difference, properly stated
A flush fitting mounts directly against the ceiling with no visible gap. The Interiors 1900 Fargo 2 Light Tiffany Flush Ceiling Light in Satin Black (£163.95, checked 9th November 2026) is one: it projects 170mm and is 415mm across. A semi flush fitting mounts on a short stem or spacer so the body of the light sits below the ceiling with daylight behind it. The Hinkley Collier 3 Light Semi Flush Ceiling Light in Heritage Brass (£166.10, checked 9th November 2026) is one: it stands 231mm tall and is 417mm across.
The two are the same diameter within two millimetres, so in a photograph they look like near relations. In the room they are 61mm apart, which sounds like nothing until the fitting is above a doorway.
Projection, and the 2.1 metre rule
Where people pass beneath a fitting we plan for about 2.1 metres of clear headroom. On a standard 2.4 metre British ceiling that leaves roughly 300mm for the whole fitting, which is the single most useful number in this article. Here is what that rules in and out across eight fittings we sell today.
| Fitting | Type | Projection | Diameter | Clear under a 2.4m ceiling | Price |
|---|---|---|---|---|---|
| Interiors 1900 Fargo 2 Light | Flush | 170mm | 415mm | 2.23m | £163.95 |
| Hinkley Collier 3 Light | Semi flush | 231mm | 417mm | 2.17m | £166.10 |
| Quintiesse Chance 2 Light | Semi flush | 254mm | 362mm | 2.15m | £166.95 |
| Hinkley Collier 4 Light | Semi flush | 293mm | 559mm | 2.11m | £229.95 |
| Interiors 1900 Dark Star 3 Light | Semi flush | 315mm | 490mm | 2.09m | £125.75 |
| Novena Caroli 3 Light | Semi flush | 380mm | 450mm | 2.02m | £176.95 |
| Endon Berenice 3 Light | Semi flush | 410mm | 456mm | 1.99m | £75.10 |
| Endon Orta 6 Light | Semi flush | 480mm | 540mm | 1.92m | £152.95 |
Four of those eight clear 2.1 metres on a 2.4 metre ceiling and four do not, and every one of the four that do not is still sold as a semi flush. The Endon Orta 6 Light Semi Flush Ceiling Light in Satin Brass (£152.95, checked 9th November 2026) comes down 480mm. None of this makes it a bad fitting. It makes it a fitting for a room with height, or for a position nobody walks under.
Which one your room wants
- Ceiling under 2.3 metres, or a hallway, landing or doorway: flush, unless the light sits over a bed or a table that nobody walks under.
- 2.4 metres with the light over seating or a bed: a deeper semi flush is fine, because nobody walks under it, so you can spend the height on something that looks better lit. Anywhere people do walk, keep to about 300mm.
- 2.5 metres and above: the whole semi flush range opens up, and a deeper fitting starts to look right rather than apologetic.
- A sloped or beamed ceiling: flush, almost always, and check the fitting is specified for an angled surface before you order.
Diameter is the other half of the decision, and it depends on the room rather than the ceiling. Our guide to what size ceiling light your room needs works that sum through. The short version is that the fittings in the table run from 362mm to 559mm across, and the larger end of that wants a room that can carry it.
Can you swap a flush for a semi flush?
Usually yes, because both fix to the same light point, each with its own ceiling plate. Three things decide it, and all three are on the product page before you buy: whether the fitting needs an earth, what it weighs, and whether the new plate covers the mark the old one left. A fitting listed as Class 1 needs an earth connection at the light point, so if there is no earth there, do not fit it. Check too that the ceiling can take the weight. If you are unsure about any of this, have an electrician fit it.
The mark is the easy one to forget. A smaller fitting replacing a larger one can leave a ring of unpainted ceiling where the old one sat, so if you are going smaller, budget for a tin of paint as well as a light.
Style, briefly, because it is the easy part
Flush and semi flush fittings come in the same decorative language as everything else. Clear or ribbed glass on brass reads traditional and suits a period hall. Opal or frosted glass gives the most even light and the least glare, which is why it ends up in bedrooms. Clear glass shades on a brass frame, like the Endon Allegra 6 Light Semi Flush Ceiling Light in Antique Brass with Clear Spiral Glass (£85.75, checked 9th November 2026), show the lamp inside, so choose a decorative one, because you will see it.
Finish matters less than people fear. A brass fitting does not have to match the door handles, and the argument for and against is in our guide to mixing metals in a room.
Frequently asked questions
What is the difference between a flush and a semi flush ceiling light?
A flush fitting mounts directly against the ceiling with no gap. A semi flush mounts on a short stem so the body of the light hangs a little below, with daylight visible behind it. The practical difference is projection: a flush fitting here comes down 170mm, while semi flush fittings range from 231mm to 480mm, so the measurement matters more than the name.
How much headroom do I need under a ceiling light?
We plan for about 2.1 metres of clear space where people walk beneath a fitting. On a standard 2.4 metre ceiling that leaves roughly 300mm for the light itself. Over a sofa, a bed or a dining table nobody stands under, you can use a deeper fitting, because the clearance rule is about walkways rather than about the whole room.
Is a semi flush light suitable for a low ceiling?
Some are and some are not. A semi flush at 231mm leaves 2.17 metres clear under a 2.4 metre ceiling, which is fine. One at 480mm leaves 1.92 metres, which is not. Where people walk beneath it on a ceiling of about 2.3 metres or less, choose a flush fitting instead and spend the money on the glass rather than on the drop.
Can I replace a flush ceiling light with a semi flush one?
Usually, because both fix to the same light point using their own ceiling plate. Check three things on the product page first: whether the fitting needs an earth, what it weighs, and the diameter of its ceiling plate against the one coming down. A smaller plate leaves a ring of unpainted ceiling where the old one sat.
How big should a semi flush ceiling light be?
Diameter is decided by the room rather than the ceiling height. The fittings in the table above run from 362mm to 559mm across, and the larger end needs a room with the floor area to carry it. Our guide to sizing a ceiling light works the calculation through for a room of any shape.
