Instantly decode any IPv4 subnet — mask, hosts, broadcast, and more.
Enter an IPv4 address with a CIDR prefix length (0–32), e.g. , , .
Network
192.168.1.0/24
Address Details
Subnet Mask — Binary
11111111.11111111.11111111.00000000The first 24 bits are the network portion; the remaining 8 bits are the host portion.
Quick Reference — Common Prefix Lengths
| Prefix | Subnet Mask | Hosts | Use case |
|---|---|---|---|
| /8 | 255.0.0.0 | 16,777,214 | Class A |
| /16 | 255.255.0.0 | 65,534 | Class B / VPC |
| /24 | 255.255.255.0 | 254 | Small LAN |
| /25 | 255.255.255.128 | 126 | Half subnet |
| /26 | 255.255.255.192 | 62 | Quarter subnet |
| /27 | 255.255.255.224 | 30 | Small segment |
| /28 | 255.255.255.240 | 14 | Micro segment |
| /30 | 255.255.255.252 | 2 | Point-to-point |
| /32 | 255.255.255.255 | 1 | Host route |
The Subnet and CIDR Calculator breaks down any IPv4 CIDR block in seconds. Enter a network like 192.168.1.0/24 and instantly get the subnet mask, wildcard mask, network address, broadcast address, first and last usable host, total host count, and IP class. Essential for network engineers, sysadmins, cloud architects, and anyone studying for CompTIA Network+ or CCNA.
CIDR (Classless Inter-Domain Routing) notation expresses an IPv4 address and its network prefix length together, e.g. 192.168.1.0/24. The number after the slash tells you how many leading bits define the network portion, with the remaining bits available for host addresses.
A /24 subnet has 256 total addresses (2^8). Two are reserved — the network address (first) and the broadcast address (last) — leaving 254 usable host addresses.
A subnet mask uses 1s to mark the network bits and 0s for host bits (e.g. 255.255.255.0 for /24). A wildcard mask is its bitwise inverse — 0s on network bits and 1s on host bits (e.g. 0.0.0.255). Wildcard masks are commonly used in ACLs and OSPF configurations.
RFC 1918 defines three private IPv4 ranges: 10.0.0.0/8 (Class A), 172.16.0.0/12 (Class B), and 192.168.0.0/16 (Class C). These addresses are not routable on the public internet and are used for internal networks and VPNs.