IP / CIDR Subnet Calculator
Calculate IPv4 and IPv6 subnets from any CIDR (e.g. 192.168.1.0/24): expand to the full address range, convert subnet masks, detect IP class and classification (private, loopback, broadcast), and check range containment. Pure algorithms, works fully offline in your browser.
Enter a CIDR block and click Calculate.
How to use the IP / CIDR Subnet Calculator
Turn any CIDR block or IP+subnet-mask combination into its full network details: address range, mask, network and broadcast addresses, usable hosts, IP class, and classification. It handles both IPv4 and IPv6 with zero external dependencies.
Supported inputs
- CIDR notation — e.g. 192.168.1.0/24, 10.0.0.5/255.255.255.0, or fd00::/64.
- An IP without a mask is treated as a host within its default class range.
What you get
- Range — the full first-to-last address span the CIDR covers.
- Mask — dotted-decimal mask, CIDR prefix length, and (IPv4) the mask in hex.
- Network / broadcast (IPv4) — the network and broadcast addresses.
- Usable hosts (IPv4) — how many usable addresses remain.
- Classification — private, loopback, link-local, multicast, broadcast or public.
You can also check containment: paste two CIDRs or an IP + a CIDR and the tool tells you whether one range is inside the other.