Subnet calculator
Enter an IPv4 address with a prefix like /24 or a mask like 255.255.255.0.
Calculate a subnet
Common subnet sizes
| Prefix | Subnet 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 | 1,022 |
| /16 | 255.255.0.0 | 65,534 |
| /8 | 255.0.0.0 | 16,777,214 |
/31 and /32 have no separate network and broadcast address, so every address is usable (/31 is used for point-to-point links).
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Related
Questions
How many hosts are in a /24?
A /24 has 256 addresses. Two are reserved for the network and broadcast address, leaving 254 usable hosts.
What is a wildcard mask?
The inverse of the subnet mask: 0.0.0.255 for a /24. Routers and firewalls such as Cisco ACLs use it to match a range of addresses.
What does CIDR mean?
Classless Inter-Domain Routing. The /24 after an address says how many leading bits are the network part; the rest identify hosts.
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