FREE · NETWORK & IT INFRASTRUCTURE

IP Range to CIDR Converter.

Convert IP ranges, address lists and overlapping blocks into the smallest set of CIDR blocks, with exclusions and a covering supernet.

CALCULATED IN YOUR BROWSER · NOTHING IS UPLOADED

Addresses, CIDR blocks or ranges (one per line)

Exclude (optional)

Minimal CIDR blocks6from 7 entries

IPv4 addresses covered: 644
IPv6 addresses covered: 1208925819614629174706176
Smallest single IPv4 supernet: 0.0.0.0/0
Smallest single IPv6 supernet: 2001:db8::/48

CIDR list

10.0.0.0/23
192.168.1.0/25
192.168.1.128/31
192.168.1.130/32
203.0.113.7/32
2001:db8::/48

Blocks

CIDR block	First address	Last address	Addresses
10.0.0.0/23	10.0.0.0	10.0.1.255	512
192.168.1.0/25	192.168.1.0	192.168.1.127	128
192.168.1.128/31	192.168.1.128	192.168.1.129	2
192.168.1.130/32	192.168.1.130	192.168.1.130	1
203.0.113.7/32	203.0.113.7	203.0.113.7	1
2001:db8::/48	2001:db8::	2001:db8:0:ffff:ffff:ffff:ffff:ffff	2^80 (1208925819614629174706176)

Overlapping and adjacent entries are merged first, then each range is split into the fewest aligned blocks.
Comments after # are ignored. Commas or semicolons can separate several entries on one line.

How to use IP Range to CIDR Converter

Paste addresses, CIDR blocks or ranges, one per line (commas also work). Optionally list blocks to exclude. Copy or download the resulting list for firewalls, allow-lists or routes.

How it works

Entries are converted to start–end ranges, merged when they overlap or touch, reduced by the exclusions, and each remaining range is cut into the largest aligned power-of-two blocks.

Example

192.168.1.0 – 192.168.1.130 becomes 192.168.1.0/25, 192.168.1.128/31 and 192.168.1.130/32; 10.0.0.0/25 and 10.0.0.128/25 merge into 10.0.0.0/24.

Questions about IP Range to CIDR Converter

Is IP Range to CIDR Converter free, and do I need an account?

Yes. This tool is free to use in your browser without an account. Processing takes place on your device.

What are the limits and what should I check?

Up to 5,000 lines; IPv4 and IPv6 can be mixed. The single supernet may include addresses that were not in the input. Everything is calculated in your browser; nothing is sent or probed on the network. Review the result before using it in your work.

Is my input sent to a server?

Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.