CIDR to IP Range Calculator: First and Last Address, Mask, Hosts
Turn CIDR blocks like 10.0.0.0/22 into first and last IP address, netmask, wildcard and usable host count. Many ranges at once.
Paste one or many IPv4 ranges, one per line, and see the first and last address, the netmask, the wildcard mask and how many hosts each block holds. Useful for firewall rules, allow lists and cloud security groups.
What it does
- Shows first and last address, netmask, wildcard mask and total addresses for each block.
- Shows the usable host range, and handles /31 and /32 correctly.
- Accepts a prefix (/24), a netmask (/255.255.255.0) or a single address.
- Warns when blocks overlap, or when host bits are set and the block is rounded down to its network.
- Up to 5,000 lines at once, all in your browser.
Example
Before
10.0.0.0/22After
Range: 10.0.0.0 - 10.0.3.255
Netmask: 255.255.252.0
Addresses: 1024Frequently asked questions
- What does /22 mean?
- The first 22 bits of the address are the network part. That leaves 10 bits for hosts, so the block holds 1,024 addresses.
- What are usable hosts?
- The first address is the network address and the last is the broadcast address, so a normal block has two fewer usable hosts than addresses. /31 and /32 are special cases.
- What is a wildcard mask?
- The reverse of the netmask. Cisco access lists and some firewalls use it, for example 0.0.0.255 for a /24.
- Does it handle IPv6?
- No, this tool is for IPv4. For IPv6 formats use the IPv6 expander on this site.
More tools
Code formatters
CSS beautifier CSS minifier HTML beautifier HTML minifier JavaScript beautifier JavaScript minifier JSON formatter YAML formatter XML formatter SQL formatter Markdown preview
Converters
Base64 encoder and decoder URL encoder and decoder Unix timestamp converter CSV to JSON JSON to CSV HTML entity encoder and decoder Number base converter Time zone converter JSON to TypeScript XML to JSON HTML to Markdown Date difference calculator
Text tools
Regex tester Remove duplicate lines Lorem ipsum generator Word counter Case converter Text diff checker
Color and images
Color converter Contrast checker Image to Base64 Image resizer
Network
Subnet calculator Download time calculator Common ports list IPv6 address expander and compressor MAC address formatter curl command builder
Server and files
Cron expression explainer chmod calculator HTTP status codes
Encoding and security
Password generator UUID generator Hash generator JWT decoder QR code generator Password strength checker Wi-Fi QR code generator