IP/CIDR Subnet Calculator
Compute subnet range, network mask, broadcast address, and usable host count for any IPv4 CIDR block. Also shows all subnets when you split a block — useful for network planning.
Network
192.168.1.0
Broadcast
192.168.1.255
Subnet mask
255.255.255.0
Wildcard
0.0.0.255
First host
192.168.1.1
Last host
192.168.1.254
Prefix
/24
Total addresses
256
Usable hosts
254
How to use the ip/cidr subnet calculator
Type a CIDR block in the form A.B.C.D/N. The calculator returns the network and broadcast addresses, subnet mask, total addresses, and the usable host range.
Formula & explanation
Mask = 32 minus N host bits. Network = IP AND mask. Broadcast = network OR ~mask. Usable hosts = 2^(32 − N) − 2 (network + broadcast excluded), except for /31 and /32 which behave specially.
Examples
192.168.1.0/24 → mask 255.255.255.0, range 192.168.1.0–192.168.1.255, 254 usable hosts (.1–.254).
Frequently asked questions
- What about /31 and /32?
- /31 (RFC 3021) is used for point-to-point links — both addresses are usable. /32 is a single host.
- IPv6?
- Not yet — IPv4 only. IPv6 is on the roadmap.
Related network & security tools
- Password Strength CheckerEstimate password entropy and time-to-crack using the zxcvbn algorithm. Shows realistic crack time estimates under different attack scenarios — far more accurate than simple strength bars.
- Hash GeneratorGenerate MD5, SHA-1, SHA-256, and SHA-512 hashes of any string. Useful for checksums, data integrity verification, and understanding hash output lengths for each algorithm.
- SSL Certificate DecoderPaste a PEM-encoded SSL/TLS certificate to inspect issuer, subject, SANs, validity period, public key, and signature algorithm. Everything runs in your browser — no certificate is uploaded.