CIDR
CIDR Calculator
Get the address range, netmask and host count from CIDR notation — with subnet splitting.
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This tool currently supports IPv4 only. All calculations run entirely in your browser.
ABOUT
CIDR calculator: address range, broadcast and host count
CIDR notation such as 10.20.0.0/22 means the first 22 bits are the network. From it this tool computes the network address, broadcast, first and last usable host, netmask and host count, shows the mask in binary and checks whether an IP falls inside the range. Useful when designing a VPC, writing security groups or choosing a Kubernetes pod CIDR.
HOW TO
How to use it
- Enter a CIDR such as
192.168.1.0/24. - Read the range, mask and host count.
- To test membership, enter an IP in the “IP in range” section.
FAQ
Frequently asked questions
How many usable hosts are in a /24?
254: of 256 addresses, one is the network address and one is the broadcast.
What are /31 and /32?
/32 is a single address; /31 is for point-to-point links and has two usable addresses (RFC 3021).
How do I split a network into several subnets?
Use the VLSM Subnet Calculator, which fits differently sized subnets efficiently.