MAC Address Randomisation

MAC address randomisation is a privacy feature in modern phone and laptop operating systems that presents a random hardware address to each WiFi network, instead of the device's permanent, factory-assigned MAC address. Its purpose is to stop networks and retail sensors from tracking a device (and therefore a person) across locations using the MAC address as a persistent identifier.

How each operating system behaves

• iOS / iPadOS: since iOS 14, "Private Wi-Fi Address" is on by default. The device generates one random address per network, which stays stable for that network across visits; iOS 18 added an optional rotating mode that changes it periodically.
• Android: since Android 10, a random per-SSID address is the default, persistent for each saved network; later versions add a non-persistent option for some networks.
• Windows 10 / 11: random hardware addresses are supported but off by default.
• While scanning: all modern devices also randomise the address in probe requests, before joining any network at all.

What it breaks, and what it does not

Randomisation largely killed passive WiFi analytics - counting probe requests to estimate footfall, or recognising the same phone across different venues - because the address changes per network and per scan. It does not break captive-portal marketing: the randomised address is typically stable on any one network, and the guest's identity comes from the sign-in itself (email or social profile), not the hardware address. A returning regular is still recognised.

What venues should take from it

Build measurement on authenticated, consented first-party capture rather than passive device tracking. It is more accurate, unaffected by OS privacy changes, and compliant by design - see WiFi data capture and why anonymous foot-traffic counting is fading.