IPv4 range to cidrs

ipv4-range-to-cidrs · version 1.0.0 · URLs & IP addresses · free, no key needed

Convert an arbitrary IPv4 address range into the minimal list of CIDR blocks that exactly covers it.

Use when you need to: ipv4 range to cidr · convert ipv4 range to cidrs · summarize ipv4 address range.

Supported

• ipv4 range to cidr
• convert ipv4 range to cidrs
• summarize ipv4 address range

Not supported

• IPv6
• hyphenated single-string ranges

Behavior

• first_address and last_address are canonical dotted-decimal IPv4 addresses; first_address must not exceed last_address as a uint32.
• cidrs is the minimal ordered list of non-overlapping CIDR blocks (largest-first at each step) whose union is exactly [first_address, last_address].
• A single address (first_address equal to last_address) yields one /32 block.

Input

• first_address (string, required): max length 15; pattern ^(?:0|[1-9][0-9]{0,2})(?:\.(?:0|[1-9][0-9]{0,2})){3}$
• last_address (string, required): max length 15; pattern ^(?:0|[1-9][0-9]{0,2})(?:\.(?:0|[1-9][0-9]{0,2})){3}$

Output

• cidrs (array of string, required): max items 64; each max length 18
• count (integer, required): min 1; max 64

Limits

• max address length: 15
• max output blocks: 64

Example

Request input:

{
  "first_address": "192.168.1.9",
  "last_address": "192.168.1.11"
}

Response:

{
  "result": {
    "cidrs": [
      "192.168.1.9/32",
      "192.168.1.10/31"
    ],
    "count": 2
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "ipv4-range-to-cidrs",
  "version": "1.0.0",
  "input": {
    "first_address": "192.168.1.9",
    "last_address": "192.168.1.11"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/ipv4-range-to-cidrs/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"first_address":"192.168.1.9","last_address":"192.168.1.11"}'

The machine-readable contract is at /v1/tools/ipv4-range-to-cidrs/versions/1.0.0.

CLI

node cli.mjs run ipv4-range-to-cidrs 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• IPv6 range to cidrs: Convert an arbitrary IPv6 address range into the minimal list of CIDR blocks that exactly covers it.
• IPv4 address offset: Add a signed integer offset to an IPv4 address, throwing if the result leaves the IPv4 address space.
• IPv4 CIDR aggregate: Merge a list of IPv4 CIDR blocks into the minimal equivalent list of non-overlapping CIDR blocks.
• IPv4 CIDR parse: Parse an IPv4 CIDR block into its network, broadcast, netmask, wildcard mask, usable host range and address counts.
• IPv4 in CIDR: Test whether a canonical IPv4 address lies in a CIDR prefix whose host bits are zero.
• IPv4 mask convert: Convert between an IPv4 prefix length, dotted subnet netmask, and dotted wildcard (host) mask.