WiFi Access Point Calculator
Size a WiFi deployment two ways at once: coverage from the ITU-R indoor path-loss model, and capacity from published client-density design figures.
Your AP datasheet beats any table here. The default is the conservative end of Cisco's published high-density figure — 10 Mbps to each of 50 clients on one access point.
Cell size by building type
α is the distance power loss coefficient from Recommendation ITU-R P.1238-13. Ranges are at 20 dBm, 5 GHz, a −67 dBm cell edge, and the cell is the regular hexagon inscribed in that radius.
| Building type | Interior model | α | Design range | Area per AP |
|---|---|---|---|---|
| Home or apartment | Closed plan, room to room | 4 | 8.7 m | 197 m² |
| Open-plan office | Open floor, no line of sight | 2.39 | 34.2 m | 3,039 m² |
| School or university | Closed plan, room to room | 4 | 7.8 m | 158 m² |
| Hotel or multi-room | Closed plan, room to room | 4 | 8.7 m | 197 m² |
| Retail or showroom | Open floor, no line of sight | 2.39 | 34.2 m | 3,039 m² |
| Hospital or clinic | Closed plan, room to room | 4 | 7.8 m | 158 m² |
| Warehouse or factory | Industrial, high ceiling | 2.8 | 31.6 m | 2,594 m² |
Client density design regimes
Cisco states the last two figures per radio interface; they are applied here per access point, which is the conservative reading. The 802.11 amendments publish no clients-per-AP figure at all.
| Regime | When it applies | Clients per AP |
|---|---|---|
| Standard | An ordinary enterprise office, where people are spread across a floor | 20 |
| High density | A training room, classroom or conference space with everyone seated together | 50 |
| Very high density | An auditorium, arena or assembly hall, with per-client bandwidth shaped down | 100 |
This is a desk estimate, not a site survey. Coverage comes from a statistical indoor path-loss model at one fixed radio budget, so a real building with metal racking, glass partitions, lift shafts or an unusual ceiling height can differ substantially. Capacity uses published design guidance, not a measurement of your own applications. Commission a survey before you buy for anything critical.
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How many access points does this building need?
Two different questions decide the answer, and a WiFi design has to satisfy both. Coverage asks how much floor one access point can reach at a usable signal level; capacity asks how many people one access point can carry at the bandwidth they need. Whichever number is larger is the number you deploy. This calculator works out both, tells you which one is binding, and shows what each user would actually get.
Coverage and capacity, sized separately
The coverage side comes from Recommendation ITU-R P.1238-13, the ITU's site-general model for indoor propagation. It gives a distance power loss coefficient for each kind of interior, which turns a link budget into a radius; the floor one access point serves is the regular hexagon inscribed in that radius, because that is the cell shape a packed grid of access points actually produces. The capacity side comes from the client-density figures Cisco publishes for enterprise and high-density design, capped by the usable throughput one access point has to share among everyone attached to it.
AP count
APs = max(⌈Floor area ÷ Area per AP⌉, ⌈Users ÷ Users per AP⌉)How to use this calculator
Enter the floor area to cover, in square metres or square feet.
Enter how many devices will be connected at the same time — concurrent, not the headcount of the building.
Pick the building type. This chooses the indoor propagation model, which is what sets the radius one access point covers.
Choose how densely people sit: standard for an ordinary office floor, high density for a classroom or training room, very high density for an auditorium.
Set the bandwidth each user needs. Web and email is around 1 Mbps, video calls around 5, HD video and large transfers 15 or more.
Adjust the usable throughput per access point if you have a datasheet figure, and add spare capacity if you want redundancy.
Read the count, then check which constraint is binding and what each user is left with.
Common situations
A house that keeps dropping upstairs
One router in the hallway is a coverage problem, not a speed problem. Enter the floor area, pick Home, and the model will usually show that a floor slab needs its own access point.
An office floor moving to all-day video calls
The floor area has not changed but the bandwidth per user has. Raise the per-user figure and watch the capacity count overtake the coverage count.
A school before a device rollout
A class of thirty connecting at the same moment is a high-density problem in a closed-plan building, which is the combination that needs the most access points per square metre.
A warehouse fitting out for scanners
Very few users, very little bandwidth each, and a large open volume. Almost always coverage-limited, and worth re-checking once racking is installed.
Why size it before you buy
The two constraints rarely agree
An open-plan office is almost always capacity-limited and a hotel almost always coverage-limited. Sizing on one and ignoring the other is how a deployment ends up either full of dead spots or full of access points fighting each other for airtime.
Client counts are not a property of WiFi 6 or WiFi 7
The 802.11 amendments publish no clients-per-access-point figure. Vendors publish a theoretical per-radio maximum in the hundreds and say plainly it is not something to design to. What decides the number is airtime and the bandwidth each user needs.
Overspending is as expensive as under-provisioning
Access points are the cheap part of a deployment. Each one also needs a switch port, PoE budget, a cable run and a licence, so a count that is twice what the building needs costs far more than twice the hardware.
It shows you which lever to pull
If throughput is the binding constraint, a better access point helps. If the client ceiling is binding, more access points help. If coverage is binding, neither helps as much as moving the ones you have.
Frequently asked questions
Usually one per floor rather than one for the house. A 2,000 sq ft floor is about 186 m², and with the closed-plan indoor model at a −67 dBm cell edge one access point covers roughly 197 m², so a single-storey home of that size needs one. A two-storey home of the same total area needs two, because a concrete or timber floor slab attenuates far more than an internal partition. Enter your own figures above rather than relying on the rule of thumb — a long, narrow layout needs more than a square one of the same area.
About 1.7 times the cell radius, centre to centre. Access points laid out on a grid produce hexagonal cells, and the distance between neighbouring centres in that packing is √3 times the radius. At the design range this calculator reports, that works out at roughly 15 m apart for a closed-plan interior and 55 m or more for an open floor. The calculator shows the exact figure for your building type. Corridors are the exception: they act as waveguides and carry signal much further along their length than across it.
Yes, and it is a real failure mode rather than just wasted money. Too many access points on overlapping channels means every one of them has to wait for the others before transmitting, so adding hardware reduces the throughput each user sees. There are only three non-overlapping 20 MHz channels at 2.4 GHz, which is why dense designs steer clients to 5 GHz or 6 GHz, cut transmit power, and use smaller cells rather than more powerful ones.
Yes — that is how every multi-access-point network is meant to work. Devices see one network name and roam between access points as they move. Give every access point the same SSID and security settings, put neighbouring ones on different channels, and let the client decide when to move. Separate names per access point force the user to switch manually and break roaming for calls.
Coverage-based planning asks whether the signal reaches everywhere, and it is driven by floor area, building materials and layout. Capacity-based planning asks whether there is enough airtime and bandwidth for everyone connected, and it is driven by user count and what those users are doing. A warehouse is usually coverage-limited; a lecture theatre is usually capacity-limited. A deployment has to satisfy both, so the count is the larger of the two.
Less than the marketing suggests. Newer amendments raise peak throughput and handle dense environments more efficiently, which lifts the capacity side of the calculation. They do not extend range much, because range is set by the link budget and the building, not the amendment — so a coverage-limited deployment needs about the same number either way. The amendment also publishes no clients-per-access-point limit; that number comes from your hardware and your RF design, which is why this calculator asks for usable throughput per access point instead of a WiFi generation.
This calculator multiplies your own price per access point by the count, because published prices go stale and vary by vendor, licensing model and volume. Get a quote and enter it. When you budget, remember the access point is not the whole cost: each one needs a switch port with PoE, a cable run, mounting, a controller or cloud licence, and often a site survey. On many projects the hardware is well under half the total.