How the calculation works
The calculator works out three AP counts and keeps the largest:
- Coverage = floors × (floor area per floor ÷ area per AP), each floor rounded up. APs don’t share coverage between floors in this estimate.
- Throughput = active devices × Mbps per active device ÷ usable Mbps per AP, rounded up.
- Clients = active devices ÷ active clients per AP, rounded up.
Active devices = people × devices per person × the share active at once, rounded up.
Switch ports = one per AP. PoE = APs × the maximum power of the AP’s PoE class at the switch (30 W for class 4), from IEEE 802.3 as used in the PoE budget calculator.
Planning assumptions, not published figures. Every default below is a starting point for a budget estimate, not a design rule, and every one can be changed:
| Building type | Area per AP |
|---|---|
| Open office | 2,500 sq ft |
| Dense office | 1,500 sq ft |
| Healthcare | 1,500 sq ft |
| Education | 1,000 sq ft |
| Warehouse | 5,000 sq ft |
- 2 devices per person, 75% of them active at once, 2 Mbps per active device
- 200 Mbps of usable throughput and 50 active clients per AP: real-world shared capacity, well below the data rate in an AP’s specifications
Walls, materials, ceiling height, racking, interference from neighbors and the AP model all change the real count. A predictive or on-site wireless survey decides the final number and placement.
Worked example
A 20,000 sq ft open office on one floor with 150 people:
- Coverage: 20,000 ÷ 2,500 = 8 APs
- Active devices: 150 × 2 × 75% = 225
- Throughput: 225 × 2 Mbps = 450 Mbps ÷ 200 = 2.25, so 3 APs
- Clients: 225 ÷ 50 = 4.5, so 5 APs
The estimate is 8 access points, set by coverage. They need 8 switch ports and, at class 4, 8 × 30 = 240 W of PoE.
The same floor planned as a dense office (1,500 sq ft per AP) needs 20,000 ÷ 1,500 = 13.3, so 14 APs. A 6,000 sq ft dense office with 300 people is set by clients instead: 450 active devices ÷ 50 = 9 APs, against 4 for coverage.
