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.
Related tools
Chmod · calculator Compute Unix permissions (octal ↔ symbolic): read, write, execute. IPv4 · decimal / binary / hex Convert an IPv4 address to a decimal integer, binary and hexadecimal. IPv4 subnet · calculator Calculate an IPv4 / CIDR subnet: mask, range, broadcast and host count. IPv6 · expand / compress Expand an IPv6 address to full form and compress it (::). Common network ports Look up a network port number and its associated service (common ports reference), in your browser. Random MAC address Generate a random MAC address (configurable format and separator), in your browser.