IP Range to CIDR Converter

Convert an inclusive IPv4 range to minimal CIDR blocks, or turn CIDRs into normalized ranges locally.

Local browser processing

Addresses and calculation inputs stay in this browser. They are not uploaded, resolved, scanned, or sent to analytics.

Mode

IP range to CIDR

Start IPv4 address

End IPv4 address

Result

Enter values and run the tool to see the local result.

How range-to-CIDR conversion works

An arbitrary IPv4 range may need several aligned CIDR blocks. Enter the inclusive start and end address to calculate the smallest exact list without including outside addresses. The reverse mode normalizes each CIDR and shows its first address, last address, and total count.

How to convert an IP range and CIDR

Choose range-to-CIDR and enter the inclusive first and last IPv4 addresses, or switch to CIDR-to-range.
Run the local calculation; large networks are summarized rather than expanded into every address.
Copy the minimal CIDR list or the normalized range rows for firewall, routing, or documentation work.

IPv4 range boundaries

This release calculates IPv4 only and does not test whether addresses are routed, assigned, public, or reachable. CIDR-to-range input is normalized to the actual network boundary.

Related network tools

IPv4 Subnet Calculator VLSM Calculator

IP range and CIDR questions

Can every IP range be represented by one CIDR?: No. One CIDR must start on its block boundary and have a power-of-two size, so arbitrary ranges often require several blocks.
Does the result include addresses outside my range?: No. The range-to-CIDR result is an exact minimal cover of the inclusive start and end addresses.
Why is my CIDR start address changed?: A CIDR represents an aligned network. The converter normalizes any host address in the input to that network's true first address.
Does this tool list every IP address?: No. It summarizes networks as ranges and counts to avoid freezing the browser on large address blocks.

How to convert an IP range and CIDR

Choose range-to-CIDR and enter the inclusive first and last IPv4 addresses, or switch to CIDR-to-range.

Run the local calculation; large networks are summarized rather than expanded into every address.

Copy the minimal CIDR list or the normalized range rows for firewall, routing, or documentation work.

IP range and CIDR questions

Can every IP range be represented by one CIDR?

No. One CIDR must start on its block boundary and have a power-of-two size, so arbitrary ranges often require several blocks.

Does the result include addresses outside my range?

No. The range-to-CIDR result is an exact minimal cover of the inclusive start and end addresses.

Why is my CIDR start address changed?

A CIDR represents an aligned network. The converter normalizes any host address in the input to that network's true first address.

Does this tool list every IP address?

No. It summarizes networks as ranges and counts to avoid freezing the browser on large address blocks.