CIDR to IP Range
Turn CIDR notation into plain address ranges. Paste blocks such as 10.20.0.0/22 and get “start - end” ranges, IPv4 or IPv6, ready for systems that do not understand CIDR. Tick an option to list only usable host addresses, or to expand each block into every individual address (up to 4,096 per block).
- Runs in your browser
- No sign-up
- Free to use
How to use CIDR to IP Range
- Paste CIDR blocks, one per line.
- Choose whether to include network and broadcast addresses.
- Optionally list every address.
- Copy or download the result.
CIDR to IP Range features
Bulk conversion
Hundreds of blocks at once.
IPv4 and IPv6
Including compressed IPv6 output.
Usable hosts
Exclude the IPv4 network and broadcast addresses.
Full expansion
Every address listed, up to 4,096 per block.
Error reporting
Invalid lines are reported with the reason.
Private
Runs in your browser.
When to use CIDR to IP Range
- Configuring firewalls or devices that take ranges instead of CIDR.
- Producing IP lists for scanning tools you are authorised to use.
- Checking which addresses a block contains.
- Converting cloud provider IP ranges for spreadsheets.
CIDR to IP Range FAQ
How do I calculate the range of a CIDR block?
The first address is the address with all host bits set to 0; the last has all host bits set to 1. For 10.20.0.0/22 that is 10.20.0.0 to 10.20.3.255.
What are usable hosts?
In IPv4, the network address and broadcast address of a subnet cannot be assigned to devices, so usable hosts run from the second to the second-last address. /31 and /32 are exceptions.
Why is the list limited?
Large blocks contain millions of addresses (IPv6 vastly more). Listing is limited to 4,096 per block; use ranges for anything larger.
Can I paste an address with host bits?
Yes. 10.20.1.7/22 is treated as its network, 10.20.0.0/22.
What is the reverse conversion?
The IP Range to CIDR tool turns a start and end address into the smallest set of CIDR blocks.
Is anything sent?
No.
Two ways to write the same addresses
CIDR notation is compact and precise, but not every system accepts it. Older firewalls, some database filters and many spreadsheets want a start and an end address instead. Converting between the two is simple arithmetic that is easy to get wrong by hand, especially across octet boundaries.
The conversion keeps the prefix bits and sets the remaining host bits all to zero for the start and all to one for the end. A /22 has ten host bits, so it spans 1,024 addresses, which crosses four values of the third octet. IPv6 works the same way with 128 bits.
Whether to include the network and broadcast addresses depends on the use. Access control lists usually want the whole block; DHCP pools and device assignments want only usable hosts. The option switches between the two.
Listing individual addresses is occasionally useful for small blocks, for example to import into an inventory. For anything large, keep the range or CIDR form, which every serious tool accepts.