Convert IPv4 subnet masks to CIDR notation quickly and accurately.
Useful for network configuration and routing.
About this tool
This tool converts subnet masks (netmasks) to CIDR notation and provides comprehensive network information
including host counts, wildcard masks, and example network addresses.
Common subnet masks
- /8 — 255.0.0.0 (16,777,214 hosts)
- /16 — 255.255.0.0 (65,534 hosts)
- /24 — 255.255.255.0 (254 hosts)
- /25 — 255.255.255.128 (126 hosts)
- /26 — 255.255.255.192 (62 hosts)
- /27 — 255.255.255.224 (30 hosts)
- /28 — 255.255.255.240 (14 hosts)
- /29 — 255.255.255.248 (6 hosts)
- /30 — 255.255.255.252 (2 hosts)
Understanding CIDR notation
CIDR (Classless Inter-Domain Routing) notation represents the subnet mask as a suffix indicating
the number of network bits. For example, /24 means the first 24 bits are used for the network portion.
Subnet mask formats
- Dotted decimal — 255.255.255.0
- CIDR notation — /24
- Binary — 11111111.11111111.11111111.00000000
- Wildcard mask — 0.0.0.255 (inverse of subnet mask)