Skip to content
Calixo

CIDR Calculator

Find subnet details from a single CIDR block like 192.168.1.0/24.

Inputs

Saved Scenarios

— select 2+ to compare

Network Address

192.168.1.0

Broadcast Address

192.168.1.255

Subnet Mask

255.255.255.0

First Usable Host

192.168.1.1

Last Usable Host

192.168.1.254

Total Addresses

256

Usable Hosts

254

Spark says

Formula

CIDR Block=IP/PrefixCIDR\ Block = IP/Prefix
Prefix
— The number of network bits, e.g. 24 in a /24

What is the CIDR Calculator?

CIDR (Classless Inter-Domain Routing) notation combines an IP address and prefix length into a single string — this calculator parses that notation directly and returns the subnet's key boundaries.

How to use it

  1. 1 Enter a CIDR block in the form IP/prefix, e.g. 10.0.0.0/16.

Worked examples

192.168.1.0/24

254 usable hosts from 192.168.1.1 to 192.168.1.254.

Try it

Frequently asked questions

Does the IP address in the CIDR block need to be the network address itself?

No — any IP address within the subnet works; this calculator finds the containing network's boundaries regardless of which specific address you enter.