IPv4 Subnet Calculator
The subnet calculator below instantly calculates, from an IP address and a mask (CIDR), the network address, broadcast address, usable address range, and number of hosts.
Understanding subnet calculation
A subnet divides an IP network into smaller segments. The subnet mask (in CIDR notation, e.g. /24) separates the network part from the host part of an IPv4 address. The network address identifies the segment, the broadcast address reaches all hosts, and the intermediate addresses can be assigned to devices.
Common CIDR masks
| CIDR | Mask | Usable hosts |
|---|---|---|
| /30 | 255.255.255.252 | 2 |
| /29 | 255.255.255.248 | 6 |
| /28 | 255.255.255.240 | 14 |
| /27 | 255.255.255.224 | 30 |
| /26 | 255.255.255.192 | 62 |
| /25 | 255.255.255.128 | 126 |
| /24 | 255.255.255.0 | 254 |
| /23 | 255.255.254.0 | 510 |
| /22 | 255.255.252.0 | 1022 |
Subnetting goes hand in hand with VLANs on a managed switch. To learn more, read our VLAN guide and browse our network switches and enterprise routers.
Indicative IPv4 calculations.
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