IP Range ↔ CIDRBrowser-local network tool
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Convert IP ranges to CIDR and merge CIDR lists

Paste ranges, CIDRs or single IPs, one per line. You get the shortest equivalent CIDR list, start–end ranges or IP + netmask lines for firewalls, allowlists and route tables.

One per line, or separated by commas. Accepts 1.2.3.4-1.2.3.9, 1.2.3.0/24, 1.2.3.0/255.255.255.0 and single IPs. IPv4 and IPv6 can be mixed.

Result

7 in → 7 out

10.0.0.0/23
172.16.0.5/32
192.168.1.10/31
192.168.1.12/30
192.168.1.16/30
192.168.1.20/32
2001:db8::/32

IPv4 addresses

524

IPv6 addresses

2^96

Common tasks

  • ip range to cidr
  • cidr merge
  • cidr aggregator
  • cidr to ip range
  • ip range calculator
  • IP 段转 CIDR

Quick answer

Paste 192.168.1.10-192.168.1.20 and get 192.168.1.10/31, 192.168.1.12/30, 192.168.1.16/30 and 192.168.1.20/32. Paste overlapping CIDRs to get a merged, minimal list.

How to use

  1. 1. Paste your listRanges, CIDRs, masks or single IPs, one per line.
  2. 2. Pick an output formatCIDR for most firewalls, start–end or IP + mask for older devices.
  3. 3. Copy or downloadUse the result in allowlists, WAF rules or route tables.

Common use cases

  • Turn a provider's IP range into CIDRs for a firewall
  • Shrink long allowlists and blocklists
  • Convert CIDRs to ranges for tools that only take start–end
  • Check if a client IP is in an allowlist

Features

  • Range to minimal CIDR list
  • Merge and de-duplicate overlapping or adjacent CIDRs
  • Output as CIDR, start–end range or IP + netmask
  • Mixed IPv4 and IPv6 input
  • Check if an IP falls inside the list
  • Copy or download the result

Related tools

Subnet CalculatorCalculate network, broadcast, usable host range, netmask and wildcard from CIDR or dotted DNS LookupLook up A, AAAA, CNAME, MX, TXT, NS, SOA, CAA, PTR and more over DNS-over-HTTPS with CloudPort LookupSearch common TCP and UDP port numbers by number, range or service: SSH 22, HTTPS 443, RDP

Frequently asked questions

Why does one range become several CIDRs?
A CIDR block must start on a boundary of its size, so arbitrary ranges are covered by a few blocks of different sizes.
What does merge do?
It joins overlapping or touching blocks, so 10.0.0.0/25 and 10.0.0.128/25 become 10.0.0.0/24.
Is my list uploaded?
No. Everything runs in your browser.