CIDR to IP Range — Free Online Tool
Convert CIDR notation into the first IP, last IP, and total addresses.
About CIDR to IP Range
The CIDR to IP Range calculator converts a CIDR block into the exact range of IP addresses it covers. Paste something like 172.16.0.0/20 and instantly see the first address, the last address, how many addresses the block contains, and the usable host count.
It's ideal for planning address allocations, writing firewall rules, configuring cloud security groups, or just understanding how big a CIDR block really is. Everything is computed locally in your browser.
How to Use CIDR to IP Range
- Type a CIDR block such as 10.0.0.0/24.
- Click Calculate.
- Read the first IP, last IP, total addresses and usable hosts.
- Use the values in your routing, firewall, or cloud configuration.
Key Features
First and last IP address of the block
Total and usable address counts
Matching subnet mask
Accepts any host address with the prefix
100% client-side and private
Frequently Asked Questions
What does this CIDR calculator do?
Enter a CIDR block such as 10.0.0.0/24 and it returns the first and last IP address, the total number of addresses, the usable host count, and the matching subnet mask.
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) writes a network as an address plus a prefix length, like 192.168.0.0/22. The number after the slash is how many bits define the network.
Can I enter any address with the prefix?
Yes. The tool normalises whatever you enter to the network's starting address based on the prefix, so 10.0.0.5/24 is treated as the 10.0.0.0/24 block.
Is it private?
Yes. All calculations run in your browser; nothing is uploaded.