Choosing the wrong cutout size is one of the most common mistakes when sourcing LED downlight housing kits. If the ceiling opening is too small, the fixture won’t fit. If it’s too large, the trim ring won’t cover the hole — and you’ll end up with a costly rework on site.
This guide walks you through standard cutout sizes, how to measure your ceiling opening, and how to match the right housing kit to your project.
What Is a Cutout Size?
The cutout size (also called hole size or opening diameter) is the circular hole you cut into the ceiling to recess the downlight housing. It is measured in millimeters (mm) or inches, and it must match the housing’s specified cutout range — otherwise the spring clips won’t hold the fixture in place.
Rule of thumb: The cutout size is always smaller than the face diameter (the visible trim ring on the ceiling). The trim ring covers the edge of the hole, so it looks clean and finished.
Standard Cutout Size Chart (Round Downlights)
Below is the standard size range for ECOLEDKIT’s COB LED downlight housing kits. Use this chart to match your ceiling opening to the right model.
| Nominal Size | Typical Cutout Range | Face Diameter Range | Power Range | Common Applications |
|---|---|---|---|---|
| 2.5″ (Mini) | Ø55–75mm | Ø62–82mm | 5–15W | Hotel rooms, corridors, washrooms |
| 3″ (Compact) | Ø55–95mm | Ø64–104mm | 9–35W | Offices, retail shops, showrooms |
| 4″ (Most Popular) | Ø55–105mm | Ø62–115mm | 9–65W | Offices, meeting rooms, lobbies |
| 5″ (Mid-Size) | Ø75–150mm | Ø88–160mm | 18–65W | Conference rooms, classrooms |
| 6″ (Large) | Ø95–200mm | Ø108–216mm | 30–65W | Shopping malls, warehouses, atriums |
| 8″ (Extra Large) | Ø150–255mm | Ø200mm+ | 40W+ | Industrial warehouses, high-ceiling spaces |
How to Measure Your Ceiling Cutout
If you’re replacing existing downlights, you don’t need to guess — measure the hole directly.
Step 1: Remove the old fixture
Take out the existing downlight (or the old trim ring) so you can see the actual hole in the ceiling.
Step 2: Measure the diameter
Use a tape measure or caliper to measure the diameter of the circular hole across the center. Measure twice — once horizontally, once vertically — to make sure it’s round and not oval.
Step 3: Compare with the housing spec
Match your measured cutout size to the housing’s specified cutout range. For example:
- If your hole is Ø75mm → it fits any housing with a cutout range that includes 75mm (e.g., 4″ round kits with cutout Ø55–105mm).
- If your hole is Ø100mm → you need a 4″ or 5″ kit with cutout range covering 100mm.
Important: Always check the exact cutout range on the product spec sheet. “4 inch” is a nominal size — the actual cutout can vary from 55mm to 105mm depending on the model and power.
Common Cutout Size Mistakes to Avoid
Mistake 1: Matching the trim diameter instead of the cutout
The trim ring (face diameter) is always larger than the cutout. Don’t measure the old trim ring and think that’s the hole size — measure the actual hole in the ceiling.
Mistake 2: Forgetting that spring clips have tolerance
Most spring-clip housings have a small tolerance (±5mm). For example, a housing rated for Ø75mm cutout will usually fit 70–80mm openings. But don’t push it too far — if the hole is 10mm off, the trim ring won’t cover it.
Mistake 3: Ordering before measuring on site
Always confirm the cutout size on site before placing a bulk order. A sample order of 5–10 pcs lets you test fit on the actual ceiling before committing to 1000+ pcs.
What If My Cutout Is Non-Standard?
If your ceiling opening is not a standard size (for example, an 88mm hole for a European project), you have two options:
- Choose a housing that covers your size — ECOLEDKIT’s 4″ range covers cutouts from 55mm to 105mm, so most non-standard openings fall within this range.
- Custom trim ring — if the hole is slightly larger than the housing’s max cutout, we can supply a larger trim ring to cover the gap. Contact us with your exact cutout size and we’ll recommend the right model.
ECOLEDKIT Cutout Size Range at a Glance
| Series | Cutout Range | Best For |
|---|---|---|
| 6100 Series (Standard Recessed) | Ø55–105mm | General commercial lighting, 9–25W |
| 6200 Series (Deep Anti-Glare) | Ø55–130mm | Offices, showrooms, UGR<19 projects |
| 6200 Series (Flat / Flush) | Ø75–200mm | Modern ceilings, large open spaces |
| Surface Mount (6105) | No cutout needed | Solid ceilings, wood panels, concrete |
Need Help Choosing the Right Cutout Size?
Send us your ceiling cutout size, project type, and required wattage — we’ll recommend the exact ECOLEDKIT model that fits.
- WhatsApp: +86 132 4938 9989
- Email: sales@ecoledkit.com
- Free samples: Ship within 7 days, MOQ from 50 sets