# IPv4 CIDR Subnet Calculator

Show network, mask, address range and conventional host capacity.

[Open this tool](https://whatson.pk/developer-ipv4-subnet-calculator/)

Category: Developer & Data

CIDR notation describes a network prefix and address range without discovering devices.

Enter the IPv4 address and prefix, then compare mask, network and host figures.

## Inputs and controls

* IPv4 address
* CIDR prefix (bits). Allowed range: 0 to 32

## How to use

* Enter IPv4 address and CIDR prefix.

* Select Process input. Read the returned values alongside the assumptions below before copying, exporting or acting on the result.


## Why use this tool

The range view helps explain how addresses fit within the same subnet.


## Before relying on the result

For /31, both addresses are shown as point to point endpoints under RFC 3021. A /32 is one host route. No reachability scan or IP lookup is performed.


## Tool limitations

For /31, both addresses are shown as point to point endpoints under RFC 3021. A /32 is one host route. No reachability scan or IP lookup is performed.

## Questions

### How are /31 and /32 handled?

A /31 shows point to point endpoints. A /32 represents one host route rather than a conventional shared subnet.

### What should I check before using IPv4 CIDR Subnet Calculator?

Check IPv4 address and CIDR prefix. Use the exact units shown beside the controls and replace any example values with your own inputs.

Source page last modified (UTC): 2026-10-04T16:58:30+00:00

This profile describes the tool. It does not execute it or supply a professional certification.