Check how many devices a router can realistically serve at a usable speed before you need a second access point.
Rated capacity is a ceiling, not a design point, so it is derated by the headroom percentage before dividing. The result is rounded up because you cannot deploy a fraction of a router. Sizing to rated capacity leaves nothing for peaks or failures; the spare-capacity line shows whether the rounded-up count actually buys useful router capacity.
WiFi Router Capacity
Units = ⌈demand ÷ (capacity per unit × (1 − headroom))⌉
Units = ⌈demand ÷ (capacity per unit × (1 − headroom))⌉ Rated capacity is a ceiling, not a design point, so it is derated by the headroom percentage before dividing. The result is rounded up because you cannot deploy a fraction of a router.
Sizing to rated capacity leaves nothing for peaks or failures; the spare-capacity line shows whether the rounded-up count actually buys useful router capacity.
This calculator takes 3 inputs: Devices needing service, Devices one router serves well, Headroom reserved for peaks. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.