User Guide

Online IPv4 CIDR Calculator — Subnet Mask and IP Range

Check an IPv4 CIDR subnet mask, network, broadcast, usable IP range and address counts.

How to use

1. Enter an IPv4 address with a prefix, such as 192.168.1.25/24.
2. Results update automatically. The left column shows network, broadcast and mask; the right shows usable range and counts.
3. Copy individual results using their copy icons.

Input and output example

192.168.0.1/24

Network: 192.168.0.0/24
Subnet mask: 255.255.255.0
Wildcard mask: 0.0.0.255
Broadcast: 192.168.0.255
Usable IP range: 192.168.0.1 ~ 192.168.0.254
Total IPs: 256
Usable IPs: 254

Background knowledge

IPv4 / CIDR

An IPv4 address has 32 bits. /24 assigns the first 24 bits to the network, leaving 8 bits for 2^8 = 256 addresses. A larger prefix number describes a smaller range.

Subnet mask

The subnet mask separates network bits from host bits; /24 corresponds to 255.255.255.0. Subtract each mask octet from 255 to obtain the wildcard mask, 0.0.0.255 for /24.

Usable IPs

For ordinary /0–/30 ranges, the network and broadcast addresses are excluded from host allocation. /24 therefore gives 256 − 2 = 254 usable addresses. /31 and /32 are exceptions; they allow 2 and 1 addresses respectively.

Notes

• IPv4 prefixes /0–/32 are supported; IPv6 range calculations are not.
• Calculated ranges do not indicate actual address allocation or network reachability.

Frequently asked questions

What can I use this online tool for?

Check an IPv4 CIDR subnet mask, network, broadcast, usable IP range and address counts.

Why does /24 have 256 addresses but only 254 usable?

For ordinary /0–/30 networks, the network and broadcast addresses are not assigned to hosts. For 192.168.1.25/24, usable addresses run from 192.168.1.1 to 192.168.1.254.

Do /31 and /32 also exclude two addresses?

No. /31 assumes a point-to-point link and reports two usable addresses; /32 reports a single address. This tool calculates IPv4, not IPv6 CIDR.

Baro Work is a collection of tools with no login. Inputs and results are not stored on the site server or in browser storage. See the translation and DNS guides for external transfers.