Subnet Calculator · Manual

How to Use the Subnet Calculator

Enter an IPv4 address, choose CIDR prefix or subnet mask input, calculate, then review the normalized network and host range.

IPv4 address

Enter four decimal octets from 0 through 255. You can append CIDR directly, for example 192.168.1.130/26.

CIDR prefix

Use a whole prefix from /0 through /32. If the IPv4 field already contains CIDR, a conflicting separate prefix is rejected instead of guessed.

Subnet mask

Use a contiguous dotted-decimal mask such as 255.255.255.192. Masks with separated one-bit groups, such as 255.0.255.0, are invalid.

Reading results

The result shows the normalized CIDR block, network, broadcast behavior, usable endpoints, subnet and wildcard masks, bit counts, and address totals. /31 and /32 use explicit edge-case semantics.

Copy, CSV, and Print / Save PDF

Exports use the current calculated result. Editing an input makes the result stale and disables those actions until you calculate again.