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Speaker Coverage Calculator

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Quick answer

A 40 foot wide seating area at a 50 foot throw needs a loudspeaker with at least a 44 degree horizontal pattern to reach both edges. A common 90 by 50 degree box covers about 100 feet at that same 50 foot throw, so it clears this room with room to spare.

Every loudspeaker data sheet quotes a horizontal and vertical coverage pattern, usually something like 90 by 50 degrees, and that number by itself tells you nothing until it is paired with a distance. The same 90 degree box covers 35 feet at a 20 foot throw and 180 feet at a 90 foot throw.

This calculator runs the trigonometry both directions: tell it your seating width and throw distance and it returns the pattern you need, or tell it a published pattern and throw and it returns the width that pattern actually covers.

Speaker coverage calculator

Measure the widest row that needs coverage, not the whole building.

From the loudspeaker to the furthest seat, not from the platform.

Checked against the width and throw above to see if it fits.

Pattern needed

44 deg

Loudspeakers with a matching coverage pattern

Top matches update when you change your numbers.

On this page
  1. How is a coverage pattern calculated?
  2. Pattern needed by seating width, at a 50 foot throw
  3. How wide does a published pattern actually cover?
  4. Common coverage patterns and what each one is for
  5. What happens if the pattern is wrong in either direction

How is a coverage pattern calculated?

A loudspeaker's horizontal pattern is a cone, and the width it covers at a given distance is straightforward trigonometry:

width covered = 2 * distance * tan( pattern angle / 2 )

Rearranged, the pattern a loudspeaker needs to cover a known width at a known distance is:

angle needed = 2 * atan( width / 2 / distance )

Two things catch installers out here. First, manufacturers usually quote the pattern at 2 kHz or higher, which is where it matters most for intelligibility, and a speaker's actual pattern narrows at low frequencies regardless of what the horn says, so treat the published number as the honest figure rather than a guarantee across the whole spectrum. Second, distance is measured from the loudspeaker to the furthest edge of the seating it must cover, not to the platform.

Pattern needed by seating width, at a 50 foot throw

Holding the throw distance constant at 50 feet and varying only the width to be covered.

At a 50 foot throw, a 40 foot wide seating area needs at least a 44 degree horizontal pattern, and an 80 foot wide area needs about 84 degrees from the same throw distance.

Horizontal pattern needed by seating width at a 50 foot throw
Seating widthPattern needed
20 ft23 deg
30 ft33 deg
40 ft44 deg
60 ft62 deg
80 ft77 deg
100 ft90 deg

Pattern needed rises faster than width once the room gets wide relative to its throw, because the angle is not proportional to the width, it is proportional to its arctangent.

How wide does a published pattern actually cover?

The four common horizontal patterns from the coverage patterns reference, and the width each one covers at six throw distances.

A 90 degree horizontal pattern covers 100 feet at a 50 foot throw and 180 feet at a 90 foot throw, almost double the width of a 60 degree pattern at the same distances.

Coverage width by published horizontal pattern and throw distance
Throw distance60 deg90 deg100 deg120 deg
20 ft23.1 ft40 ft47.7 ft69.3 ft
30 ft34.6 ft60 ft71.5 ft103.9 ft
50 ft57.7 ft100 ft119.2 ft173.2 ft
70 ft80.8 ft140 ft166.8 ft242.5 ft
90 ft103.9 ft180 ft214.5 ft311.8 ft
120 ft138.6 ft240 ft286 ft415.7 ft

These are the horizontal figure only. A wide horizontal pattern paired with a narrow vertical pattern, such as 100 by 60 rather than 100 by 100, is the usual way manufacturers keep energy off the ceiling and the back wall while still covering a wide seating area.

Common coverage patterns and what each one is for

A 90 by 50 degree pattern is the default point-source box for a wide room of normal depth, while 60 by 40 keeps energy off the side walls in a narrow, deep sanctuary.

Standard loudspeaker coverage patterns and their typical use
PatternTypical use
90 by 50 degreesThe default point-source box, wide rooms of normal depth
60 by 40 degreesNarrow, deep rooms and long throws; keeps energy off side walls
100 by 100 degreesFills, front fills and very wide fan-shaped rooms
120 by 60 degreesShort-throw wide coverage, small rooms and balconies
70 by 70 degreesUnder-balcony delays and square-ish side rooms

What happens if the pattern is wrong in either direction

Too narrow leaves the side seats thin no matter how much power the amplifier has, because coverage is a geometry problem, not a loudness problem. Turning the system up does not widen the pattern, it just makes the center louder and the sides comparatively worse.

Too wide wastes energy on the side walls and the back of the room, which comes back as reflections that reduce intelligibility rather than adding useful level. A wider pattern than the room needs also throws away gain before feedback on any open microphone in the room.

The honest fix for either case is usually a different loudspeaker rather than a different aim angle. A box like the JBL Professional EON712 Powered PA Speaker, 12 inch, 1300 Watt at 100 by 60 or the Electro-Voice ZLX-12P-G2 12in. 2-Way Powered Loudspeaker with Bluetooth at 90 by 60 covers most rooms of normal proportions, while a narrower box or a column such as the QSC KC12-BK System Column Line Array PA suits a long, deep space where a wide pattern would only add echo.

Frequently asked questions

How do I calculate the coverage pattern I need?

Take the width you need to cover and the distance the loudspeaker will be throwing from, and the angle needed is twice the arctangent of half the width divided by the distance. A 40 foot wide room at a 50 foot throw needs at least a 44 degree horizontal pattern. Manufacturers quote their loudspeakers pattern on the data sheet, usually at 2 kHz or higher.

What does a 90 by 50 degree speaker pattern mean?

The first number is the horizontal spread and the second is the vertical spread, both measured conically from the front of the loudspeaker. A 90 by 50 box spreads 90 degrees side to side and 50 degrees up and down, which is why it is the default choice for a wide room of normal depth: enough horizontal reach for most seating widths and a vertical pattern narrow enough to miss the ceiling and stay off the back wall.

Should I measure coverage from the loudspeaker or from the platform?

From the loudspeaker to the furthest seat it has to reach, never from the platform edge. The loudspeaker is usually set back and raised above the platform, so measuring from the platform undercounts the real throw distance and results in a pattern calculation that looks fine on paper but leaves the back rows underserved in the room.

Why do two loudspeakers with the same power cover different widths?

Because coverage width depends on the horizontal pattern and the throw distance, not on wattage. A 500 watt loudspeaker with a 60 degree pattern covers less width at any given distance than a 200 watt loudspeaker with a 100 degree pattern. Power decides how loud the coverage area gets; pattern decides how big the coverage area is in the first place.

Is a wider coverage pattern always better?

No. A pattern wider than the room needs throws energy at the side walls and the back of the room, which returns as reflections that hurt intelligibility rather than adding useful level, and it reduces gain before feedback for any open microphone in the room. Match the pattern to the actual seating width at the actual throw distance rather than buying the widest box available.

Does the vertical pattern matter as much as the horizontal one?

Yes, for a different reason. The vertical pattern controls how much energy hits the ceiling and how far down the front rows get covered, which is why a wide horizontal pattern is usually paired with a narrower vertical one, such as 100 by 60 rather than 100 by 100. This calculator works the horizontal number, which is usually the harder one to get right in a fixed installation.

Researched, not professional advice. This page is compiled from published manufacturer specifications, operator manuals, FCC rules, published standards and owner-review consensus, not hands-on testing. Sound system design, rigging loudspeakers overhead, and any electrical work are jobs for a qualified professional: have flown loudspeakers and their attachment points signed off by a structural engineer or a certified rigger, and have all wiring done by a licensed electrician to your local code. Wireless microphone rules change, so confirm the current FCC position before buying. As an Amazon Associate we earn from qualifying purchases.