Network & Debug
IPv4 Subnet Calculator
Calculate IPv4 network and broadcast addresses, host ranges, address counts, subnet and wildcard masks locally from an IP and CIDR prefix or contiguous mask, including /31 and /32.
About this tool
Enter an IPv4 address and CIDR prefix or contiguous subnet mask to inspect network boundaries, broadcast and host ranges, and address counts. Calculations stay local without network scanning.
Best use cases
- Check subnet boundaries when configuring a LAN or server.
- Compare CIDR prefixes with dotted subnet masks and copy the results for documentation.
How to use it
- Enter a bare IPv4 address such as 192.168.1.42.
- Enter a prefix from 0 to 32, such as 24 or /24, or a contiguous mask such as 255.255.255.0.
- Calculate and inspect the network, broadcast, host range and address counts, then copy the results.
FAQ
How are /31 and /32 handled?
/31 is interpreted as a point-to-point network with two endpoints and no broadcast address. /32 represents a single host with no broadcast address.
Can all addresses in the host range be assigned?
This calculates numeric boundaries. Special-use, reserved and allocation rules still apply; a calculated address is not necessarily reachable.
Are IPv6 or non-contiguous masks supported?
This page supports IPv4 only and rejects non-contiguous masks. It never enumerates or scans the entire address list.