Ceiling Grid Calculator
The tile count for a suspended ceiling, the size of the cut border tiles when the grid is centred in the room, and the main runners and cross tees to order.
Centre the grid so the cut tiles at opposite walls match and none is a sliver: for each direction, the full tiles are the floor of room ÷ tile, and the border is half the remainder.
How the ceiling grid calculator works
Centre the grid so the cut tiles at opposite walls match and none is a sliver: for each direction, the full tiles are the floor of room ÷ tile, and the border is half the remainder. If a border comes out under half a tile, shifting the grid by half a tile makes it larger and more even. Main runners run one way at the tile spacing; cross tees complete the grid; add 10% waste to tiles for cuts.
Formula: full tiles = floor(room ÷ tile); border = (room − full × tile) ÷ 2; tiles = ceil(room_L ÷ tile_L) × ceil(room_W ÷ tile_W)
Worked examples
| Inputs | Tiles to order | Note |
|---|---|---|
| 7.3 × 4.5 m with 600 × 600 tiles | 115 | 13 × 8 = 104 tiles, order 115 |
| 6 × 4 m, 1200 × 600 tiles | 39 | 5 × 7 = 35, order 39 |
| 20 × 15 ft office, 2 × 4 ft tiles | 42 | 5 × 8 = 40, order 42 |
FAQFrequently asked questions
Why center the grid?
So the cut tiles at opposite walls are the same size and the ceiling looks symmetrical; an uncentred grid ends with a full tile on one side and a sliver on the other. Centring also keeps light fittings in the grid pattern symmetrical.
Why shift by half a tile?
If centring leaves borders narrower than half a tile they look mean and are hard to cut and support. Dropping one full tile and re-centring widens both borders by half a tile — the standard installer’s trick.
What about lights and diffusers?
They replace tiles in the grid; count them and subtract from the tiles, or leave the spares. Heavy fittings need independent support, not the grid.
How much grid do I need?
Main runners every 1.2 m across the room, hung on wires every 1.2 m along their length, with cross tees at the tile spacing between them and wall angle around the perimeter. The runner row estimates the lengths; the perimeter is 2 × (L + W).
Where these figures come from
- Sabine (1922) — Collected Papers on Acoustics — the reverberation-time equation
- CIBSE Guide A — Environmental design — daylight, comfort and ventilation criteria
- Neufert — Architects' Data — the standard reference for space and dimension
- International Code Council — International Building Code — occupant load and egress factors
- International Code Council — publisher of the model codes most US jurisdictions adopt
Last checked: September 2026. Formulas are the standard building-science and code relationships; default thresholds are common international values and should be replaced with the ones in your code.