Guide
MAC address vs IP address
A MAC address identifies a network chip; an IP address identifies a position on a network. Compare formats, lifetimes and privacy.
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They look like two kinds of address for the same machine, and beginners often use them interchangeably. In practice they live on different layers of networking, change for different reasons, and are seen by completely different observers.
Two layers, two jobs
- MAC address — Media Access Control, a hardware identifier burned into a network interface (or assigned per connection by modern firmware). It identifies which physical interface is on a local network segment. Switches use it to decide which port a frame goes to.
- IP address — a logical address assigned by software, which identifies where a device sits on a network so that packets can be routed across the internet. It changes when you move networks or when your ISP re-leases — see why your IP changes.
One sentence to keep them apart: the MAC answers "which adapter?", the IP answers "which network location?"
Format and permanence
| MAC address | IP address | |
|---|---|---|
| Format | Six hex pairs: 3C:5A:B4:1F:2D:88 | IPv4 203.0.113.45, or IPv6 2001:db8::1 |
| Length | 48 bits (64 in EUI-64 form) | 32 bits (IPv4) or 128 bits (IPv6) |
| Assigned by | Manufacturer (OUI prefix) or OS randomisation | Router via DHCP, ISP, or manually |
| Scope | Local network segment only | Local network, then translated to a public address |
| Changes | Rarely, unless randomised or spoofed | Often — every reconnect is a fresh chance |
| Visible to websites | Never | Always (the public one) |
The first three pairs of a MAC are the OUI, which identifies the manufacturer — a fact that makes MAC addresses weakly identifying on a LAN, and one that local network tools display.
What websites and networks see
This is the distinction that matters in practice:
- A website sees your public IP address — never your MAC. Frames carrying MAC addresses are stripped at the first router, and your MAC never crosses the internet. Anyone claiming a site can read your MAC is wrong.
- Your router and local network see your MAC for every device, together with the local IP the DHCP server handed out. That pairing is how DHCP reservations, parental controls and device lists work — see who is on your Wi-Fi.
The IP checker therefore shows your network details and nothing hardware-related: address, ISP, ASN, location — no MAC.
MAC randomisation and spoofing
Because MAC addresses are stable, they used to be a tracking vector: a shopping centre's Wi-Fi or a campus network could recognise your phone every visit. Every major platform now randomises the MAC per network or per session — iOS, Android, Windows and macOS all have the setting. That is also why MAC-based access control is weak security: a randomised or spoofed MAC walks straight past it.
To see your own: ip link or ip addr on Linux, ifconfig on macOS, getmac /v or ipconfig /all on Windows, and the network details screens on phones.
Where each is useful
| Task | Use |
|---|---|
| Stable local IP for a server or printer | DHCP reservation keyed to the MAC |
| Identifying which device is on the Wi-Fi | MAC + vendor prefix in the client list |
| Block-list removal, abuse reporting | Public IP (reputation) |
| Blocking one device from a network | MAC filter — weak, easily bypassed |
| Paying respect to the OSI model | Both: L2 MAC, L3 IP |
Bottom line: MAC tells your local network which adapter is present; IP tells the internet where to deliver packets. Only the IP leaves your house — and it is the one worth protecting, because it is the one every website can collect.
Frequently asked questions
Can a website see my MAC address?
No. MAC addresses exist only inside the local network segment; the first router removes them. Websites see your public IP address and browser metadata, never hardware identifiers.
Does my IP address change when I connect to a different network?
Yes. You get a local address from that network's router and a public address from its ISP, so both change. Your MAC stays with the device, which is why phones randomise it per network.
Should I change my MAC address?
Modern devices do it automatically for privacy. Spoofing manually can bypass a MAC filter, but that is not a security control anyone should rely on — use WPA2/WPA3 and strong Wi-Fi passwords instead.
Keep reading
- Static vs dynamic public IP
- Public vs private IP addresses
- How to fix an IP address conflict
- Is an IP address personal data?
- Check your IP address from the command line
- How to find your IP address on a computer
- How to find your router's IP address
- How to trace an IP address
- What can someone do with my IP address?
- What is a local IP address?
- How to change your IP address
- How to hide your IP address
- Browse all IP guides
- Check my public IP address
Check any other IP address
Investigating a suspicious login, a spam email header or a server log entry? Run any IPv4 or IPv6 address through the same geolocation and proxy checks.