Networking tool

IPv4 Subnet Calculator

Calculate network boundaries, masks and usable host ranges from an IPv4 address and CIDR prefix. The calculation runs entirely in your browser.

IPv4 Client-side No API

Network input

Enter an address and prefix, or enter CIDR notation directly in the address field.

IPv4 address Example: 172.17.174.1 or 172.17.174.1/23

CIDR prefix

/

Common

Your input stays on this device. No address entered here is sent to the website backend.

Subnet details

Standard classless IPv4/CIDR calculation with RFC 3021 handling for /31 point-to-point networks.

Ready to calculate Enter an IPv4 address and CIDR prefix to see the network boundaries and host range.

Quick reference

Common IPv4 prefixes

/24255.255.255.0254 usable hosts

/25255.255.255.128126 usable hosts

/26255.255.255.19262 usable hosts

/27255.255.255.22430 usable hosts

/28255.255.255.24014 usable hosts

/29255.255.255.2486 usable hosts

/30255.255.255.2522 usable hosts