Ceiling speaker spacing calculator

How many ceiling speakers does the room need, and how far apart? Enter the ceiling height, the speaker's coverage angle and the room size.

How it works

A ceiling speaker covers a circle at ear height. A 90° speaker in a 10 ft ceiling, heard by seated people, covers a circle 12 ft across. How far apart you put those circles decides how even the sound is:

• Edge to edge: circles just touch (spacing = 2 × radius). Fewest speakers, with quieter spots between them. Fine for background music.
• Minimum overlap: on a square grid, every point falls inside at least one circle (spacing = radius × √2). A common choice for paging and general use.
• Center to center: each speaker's circle reaches its neighbors (spacing = radius). Many more speakers, and the most even level, which speech intelligibility benefits from.

Which layout suits which use is industry convention, not a hard rule.

The speaker count rounds up the rows and columns on a square grid, starting half a spacing in from the walls.

Field notes

• Use the manufacturer's coverage angle, usually quoted at the −6 dB point, and use the figure for the frequency range that matters (speech band for paging). Coverage narrows at higher frequencies.
• Ear height: about 4 ft (1.2 m) for seated listeners and about 5.5 ft (1.7 m) for standing ones, such as lobbies and retail.
• Low ceilings need more speakers, not louder ones. Halve the distance from ceiling to ears and each speaker covers a quarter of the area.
• High ceilings widen the circles, but every speaker is further away and the room's reverb has more say. Pendant speakers or a different design may serve better.
• After the layout, size the amp. Add up the taps in the 70V line calculator.