In short
As a first estimate, one commercial access point covers roughly 100 to 150 square metres of open-plan office, and a unit serves around 25 to 30 busy devices comfortably. Count both, coverage and capacity, and take the larger number. Walls, racking and building fabric shrink the coverage figure fast, which is why the estimate is a starting point and a survey is the answer.
More is not better: overlapping units on a bad channel plan interfere with each other, so placement matters more than quantity.
How many access points is the WiFi version of how long is a piece of string, but unlike the string there is a respectable way to estimate it, and knowing the method is worth more than the number, because it shows you what changes the answer.
Two things drive the count, and every office needs to satisfy both. Coverage is whether the signal reaches every corner at usable strength. Capacity is whether the units can serve every device at once when the building is full. Small offices are usually coverage-driven; dense ones are capacity-driven; and the count is whichever demands more.
The coverage estimate
In open-plan space with ordinary partitions, one well-placed commercial access point covers somewhere around 100 to 150 square metres. Divide the floor area and you have the coverage baseline: a 400 square metre floor suggests three or four units.
Then the building takes its cut. Blockwork and brick walls, foil-backed insulation, metal racking, lift shafts, coated glass and long thin layouts all shrink the effective footprint, sometimes dramatically, and 5GHz, the band doing most of the work in a modern office, travels less well through obstacles than the numbers on the box suggest. An older building or a warehouse mezzanine can halve the coverage figure, which is why two offices with identical floor plates can need very different counts.
The capacity estimate
Count devices, not people. Each person brings a laptop and a phone, then add the shared kit, printers, sensors, card readers, meeting room screens, guest devices, and the total is typically two and a half to three times the headcount. A commercial access point serves dozens of connections, but serving is not the same as serving well: around 25 to 30 actively busy devices per unit is a comfortable planning figure for an office doing video calls and cloud work all day.
Forty people in 200 square metres is therefore a capacity problem before it is a coverage one: the floor area says two units, the device count says three or four. Meeting rooms deserve their own thought, because twelve laptops on video in one room is a burst of demand in a small space.
Why more is not better
The tempting fix for any doubt is to add another unit, and it backfires more often than it helps. Access points share a finite set of radio channels, and units placed too close on a poor channel plan interfere with each other, so devices spend airtime coping with the noise rather than moving data. A floor can genuinely get slower after kit is added to it.
The other quiet requirement is wired backhaul: every access point needs a cable back to the switch, because units that relay wirelessly to each other halve their airtime with every hop. The count therefore comes with a cabling plan attached, and an office short of ceiling outlets has a cabling question before it has a WiFi one.
When the estimate is enough, and when it is not
For a small, regular, single-floor office with normal partitions, the arithmetic above gets you close, and candour says so: two or three units placed sensibly will do the job, and nobody should sell you a design exercise for a floor a designer can see from the door. The estimate stops being enough when the building argues back, multiple floors, thick walls, racking, coated glass, awkward shapes, or when the office is dense enough that capacity is driving the count. At that point a wireless survey measures the building instead of guessing at it, and the extra confidence usually costs less than one access point bought on spec that lands in the wrong place.
How Core Comms can help
We design and install WiFi installations for offices, warehouses and multi-site businesses across Manchester, the North West and West Yorkshire. The count comes from a survey that measures coverage and capacity against how your space is actually used, the units go in on wired backhaul with a proper channel plan, and the data cabling behind them is installed and tested by the same team.
If you are counting access points on the back of an envelope, talk to our team or call 0330 838 1000 and we will turn the estimate into a design.
Ready to fix your office network?
Talk to Core Comms about a network review and we'll help you get to the root of the problem.
Get in touch