Convert IP Address Range to CIDR Notation
Convert an IPv4 address range (start–end) into the minimal CIDR blocks.
🔒 100% client-side — no data sent
Turn a start-to-end IP range into the minimal CIDR blocks. A fast tool for planning networks, firewalls and ACL rules. All calculations stay 100% in your browser, fully private.
What is it for?
- ▸ Convert an IP range into one or more CIDR blocks
- ▸ Prepare firewall rules and access control lists
- ▸ Aggregate addresses into CIDR prefixes
- ▸ Estimate the number of blocks needed for a range
FAQ
What is CIDR notation?
CIDR describes an address block as an IP followed by a prefix (e.g. /24), indicating how many network bits are fixed.
Does an IP range always map to a single CIDR block?
No. An arbitrary range may need several CIDR blocks to cover it exactly without overflow.
Is the data I enter kept anywhere?
No, all processing happens in your browser and nothing is sent or stored.