How many Wi-Fi access points does an office need?

Why the box coverage figure misleads

Packaging often promises coverage of several hundred square metres. That figure assumes open air, no walls and a handful of devices, which describes almost no office. Real buildings have partition walls, concrete cores, kitchens full of metal and staff with a laptop and a phone each. Coverage is only half the question; capacity, meaning how many devices can talk at a decent speed at the same time, is the other half.

An access point can reach a long way at a low speed. What you want is a strong signal at every desk, so that devices connect at a fast rate, finish their transfers quickly and leave the air free for others. A slow device holds the airtime for longer, which drags down everyone else connected to the same access point. Designing for strong signal everywhere keeps the whole network quicker, not just the desks nearest the cupboard.

Plan for people and devices, not just area

Count people, then multiply by the devices they carry. A typical office worker brings a laptop and a phone, and sometimes a tablet or a smartwatch. Add printers, meeting-room screens, wireless presentation units and any smart devices. Twenty-five staff can easily mean seventy wireless clients. Remember the devices that arrive with visitors, contractors and the occasional client workshop, and the laptops that stay connected while their owners are in a meeting room.

Each modern business access point handles dozens of clients comfortably, but performance falls off as the count climbs, especially on video calls. A sensible design keeps each access point to around twenty-five to thirty-five active users. A meeting room that holds twelve people on video at once may justify its own unit even if the floor plan says coverage is fine.

What walls and building materials do

Plasterboard partitions cost a little signal. Concrete, brick, lift shafts, toilets with tiled walls and fire doors cost a lot. Many older Auckland and Hamilton buildings have heavy internal walls that carve a floor into zones, each needing its own access point regardless of the total area. Kitchens, bathrooms and server rooms with metal racks also tend to create shadows behind them, which is easy to miss on a plan.

Glass is tricky too. Modern energy-efficient glazing often has a metallic coating that reflects Wi-Fi strongly, so a glass-walled boardroom can be a dead spot right next to the open office. Multi-level offices need each floor treated separately, because floors block signal more than most people expect. Testing with a phone app in each room before the fit-out is finished can reveal these surprises while it is still easy to add a cable run.

A worked example

Picture a 400 square metre office in a converted warehouse with 30 staff, an open-plan area, four glass meeting rooms and a kitchen behind a block wall. Area alone suggests two access points. People and devices suggest two to three. The block wall and coated glass push it to three or four, with one placed to cover the meeting rooms and one covering the kitchen and break area where people take calls.

Spending a little more on one extra unit is usually cheaper than the lost time from patchy coverage, and it gives you headroom when the team grows. It also means that if one access point fails, its neighbours can cover most of the gap while a replacement is arranged, so the office keeps working rather than losing Wi-Fi in a whole wing.

Placement matters as much as the number

Ceiling mounting in the middle of each zone is ideal. Access points tucked in a cupboard, on top of a filing cabinet or behind a TV throw signal in odd directions and lose strength through whatever surrounds them. Each one should have its own data cable back to a switch, which also powers it through PoE, so there is no power point needed on the ceiling.

Avoid placing access points too close together at full power. They then hear each other and compete, which lowers performance. A good design overlaps coverage just enough for laptops to roam smoothly between them. Business systems can lower transmit power automatically so neighbouring units share the space politely. On a consumer router there is no such coordination, which is one reason simply adding more of them can make things worse.

When to get a survey

For small, simple spaces, the rule of thumb is often enough. For larger floors, multiple levels, heavy walls, warehouses or anywhere you plan to run voice over Wi-Fi, a survey pays for itself. A predictive survey uses the floor plan and wall types to model coverage; an onsite survey measures the real signal with test equipment.

Either way, ask for a drawing that shows where each access point goes and why. That drawing becomes part of your network documentation and makes future changes far easier. Store it with the cabling records and the switch port list, so anyone working on the network later can see which cable feeds which unit and which spare runs are available.