Developer tools
IP Subnet Calculator
Calculate the network address, broadcast address, usable host range, and host count for an IPv4 address and subnet locally in your browser.
Enter an IPv4 address with a CIDR prefix length or a contiguous dotted-decimal subnet mask to see the network address, broadcast address, host range, host count, and address class.
Subnet math runs locally in your browser; your address is not uploaded or stored.
Work out subnet details without uploading anything.
Enter an IPv4 address with a CIDR prefix length or a contiguous dotted-decimal subnet mask to see the network address, broadcast address, subnet and wildcard masks, usable host range, host count, and address class. Prefix lengths from /0 to /32 are accepted, including the RFC 3021 /31 point-to-point and /32 single-host cases. Everything runs locally in your browser, so your address is not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What does the IP subnet calculator show?
It shows the network address, broadcast address, subnet mask with its CIDR prefix, wildcard mask, usable host range, number of usable hosts, and the address class. For example, 192.168.1.10 with a /24 prefix gives network 192.168.1.0, broadcast 192.168.1.255, and 254 usable hosts from 192.168.1.1 to 192.168.1.254.
Which subnet inputs are accepted?
Enter a dotted-decimal IPv4 address with octets from 0 to 255, plus either a CIDR prefix length from 0 to 32 or a contiguous dotted-decimal subnet mask such as 255.255.255.0. Non-contiguous masks like 255.0.255.0 and IPv6 addresses show a clear error instead of a result.
How are /31 and /32 networks handled?
A /32 prefix is a single host, so the result shows that address with a host count of 1. A /31 prefix is an RFC 3021 point-to-point link with 2 usable addresses and no separate network or broadcast subtraction. Prefixes of /30 or shorter subtract the network and broadcast addresses from the host count.
Do my values stay private?
Yes. The subnet calculation and copy action run locally in your browser. CodeASystem does not upload or store the values you enter.