ToolPony.comDocumentation

IP subnet calculator

Inspect IPv4 and IPv6 networks, masks, ranges and address counts, or test whether an IP belongs to a CIDR block.

Get started

  1. Use the example values or enter your own measurements.
  2. Calculate, then copy the result or download the available details.

Example

Input

192.0.2.129 /27

Expected result

Network 192.0.2.128/27, 30 usable hosts

Try it

Good to know

The calculation runs in your browser. Use consistent units in fields with no explicit unit.

Calculation method

AND the address with a prefix mask to find the first address. The host part has 2^(address bits − prefix) possibilities. IPv4 /31 uses legacy host counting by default, with an RFC 3021 point-to-point option. An inline CIDR prefix takes precedence.

Addresses=2w−p,w∈{32,128}\text{Addresses}=2^{w-p},\qquad w\in\{32,128\}

IPv4 accepts a prefix length or a contiguous dotted mask. For example, 192.0.2.129 with 255.255.255.224 gives the same network as 192.0.2.129/27.

The prefix-size category follows the comparison tool’s A/B/C convention. The historical address class appears separately. Use the address range for CIDR membership. The optional point-to-point setting changes /31 host counting only.

Calculation mode

IPv4
  • IPv4 address or CIDR
  • Prefix or subnet mask
  • Use both addresses on /31 point-to-point links
IPv6
  • IPv6 address or CIDR
  • Prefix
Check address membership
  • CIDR network
  • Address to check