Enter an IPv4 address with a CIDR prefix, such as 192.168.1.0/24, and this calculator works out the network address, broadcast address, subnet mask, wildcard mask, the first and last usable host, the total number of addresses and the number of usable hosts. CIDR notation packs a subnet mask into a single number after the slash, which is compact but not always obvious to reason about, so seeing every derived value at once removes the guesswork. This is exactly what you need when planning subnets, writing firewall rules, or filling in a cloud VPC configuration. Prefixes from /0 to /32 are supported, including the small edge cases like /31 point to point links and /32 single hosts. All math runs locally in your browser with plain integer arithmetic, so nothing is sent to a server.
From an IPv4 block like 192.168.1.0/24 it returns the network address, broadcast address, usable host range, subnet mask and total host count.
For prefixes up to /30 it is two raised to the number of host bits, minus two for the network and broadcast addresses.
A /32 describes a single address and a /31 point to point link has two addresses with no separate broadcast, so the usable count is reported accordingly.
Enter an IPv4 address with a CIDR prefix, such as 192. 168.
Yes. CIDR Calculator is completely free, with no sign-up and no usage limits.
Yes. CIDR Calculator runs in any modern web browser. There is nothing to download or install.
Yes. CIDR Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.