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Subnet And IP Address Calculator

Calculate IPv4 subnet details including network address, broadcast address, usable host range, subnet mask, wildcard mask, and CIDR notation.

Enter an IPv4 address such as 192.168.1.10.

Enter the slash value from 0 to 32, such as 24 for /24.

Status: initial

Results

Awaiting calculation

Guide

Introduction

IPv4 subnetting divides a network into address blocks. This calculator takes an IPv4 address and CIDR prefix length, then returns the network address, broadcast address, usable host range, subnet mask, wildcard mask, and binary breakdown.

Purpose

Use this calculator to check subnet math while planning small networks, studying networking concepts, configuring routers, reviewing firewall rules, or validating CIDR notation.

How subnet calculation works

The calculator converts the IPv4 address and subnet mask into 32-bit numbers. The network address is found with a bitwise AND between the IP address and mask. The broadcast address is found by combining the network address with the wildcard mask.

Variable explanations

IPv4 address

A dotted-decimal address with four octets from 0 to 255, such as 192.168.1.10.

CIDR prefix length

The slash number that indicates how many bits belong to the network prefix, such as /24.

Subnet mask

The dotted-decimal mask that separates network bits from host bits.

Wildcard mask

The inverse of the subnet mask, commonly used in access control list matching.

Formula and method guide

Subnet mask

Mask = first N bits set to 1, remaining bits set to 0

  • N is the CIDR prefix length from 0 to 32.
  • A /24 mask is 255.255.255.0.

The prefix length tells how many bits identify the network portion of the address.

Network address

Network address = IP address AND subnet mask

  • The IP address is converted to a 32-bit number.
  • The subnet mask keeps the network bits and clears host bits.

The result is the first address in the subnet block.

Broadcast address

Broadcast address = network address OR wildcard mask

  • Wildcard mask is the inverse of the subnet mask.
  • Host bits are set to 1.

The result is the last address in the subnet block for ordinary IPv4 subnets.

Total addresses

Total addresses = 2^(32 - prefix length)

  • A shorter prefix leaves more host bits and more addresses.

For example, /24 leaves 8 host bits, so it contains 256 total addresses.

Worked examples

Typical home subnet

  1. Enter 192.168.1.10 as the IPv4 address.
  2. Enter 24 as the CIDR prefix length.
  3. The network address is 192.168.1.0 and the broadcast address is 192.168.1.255.

Small /30 subnet

  1. Enter an IPv4 address in a /30 network.
  2. The total address count is 4.
  3. The common usable host count is 2.

Point-to-point /31 subnet

  1. Enter a prefix length of 31.
  2. The calculator treats both addresses as usable for point-to-point style networks.
  3. Review your device and routing requirements before using /31.

Single-host /32 route

  1. Enter a prefix length of 32.
  2. The network and broadcast values are the same address.
  3. The result represents a single IPv4 address.

Common mistakes

Mixing subnet mask and IP address

A subnet mask such as 255.255.255.0 is not usually assigned as a host IP address.

Forgetting reserved addresses

Traditional IPv4 subnets reserve the network and broadcast addresses, reducing ordinary usable host count by two.

Assuming classful rules only

Modern IPv4 routing commonly uses CIDR, so the prefix length matters more than old class A, B, and C defaults.

Using IPv6 in an IPv4 field

This release is IPv4-only. IPv6 subnetting is a future extension.

FAQs

What does this subnet calculator calculate?
It calculates IPv4 network address, broadcast address, usable host range, subnet mask, wildcard mask, total addresses, and usable hosts from an IP address and CIDR prefix.
What is CIDR notation?
CIDR notation writes an address with a slash prefix, such as 192.168.1.10/24. The slash number tells how many bits are network bits.
What is a subnet mask?
A subnet mask separates the network portion of an IPv4 address from the host portion.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask and is often used in access control lists.
What is the network address?
The network address is the first address in the subnet block and identifies the subnet itself.
What is the broadcast address?
The broadcast address is the last address in a traditional IPv4 subnet block.
Why are usable hosts sometimes total addresses minus two?
Traditional IPv4 subnets reserve the network address and broadcast address, leaving the rest for hosts.
How are /31 networks handled?
The calculator treats /31 networks as two usable addresses, which is common for point-to-point links.
How are /32 networks handled?
A /32 represents a single IPv4 address, so network, broadcast, first usable, and last usable are the same.
Does this support IPv6?
No. This release focuses on IPv4 CIDR calculations. IPv6 support is a future extension.
Can I enter a dotted subnet mask instead of CIDR?
Not in this release. Enter the CIDR prefix length from 0 to 32.
What is a private IPv4 address?
Private IPv4 ranges include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.
Can this replace network engineering review?
No. It helps check subnet math, but production network changes should be reviewed and tested by qualified administrators.
Does this calculator send IP data to a server?
No calculator-specific server submission is required. The calculation runs through the site calculator engine.
Are formulas calculated in the page component?
No. The page renders a registered calculator specification and the Formula Engine performs the subnet calculation.

References

Related calculators

Last updated and version history

Last updated: 2026-07-05

  • 1.0.0 (2026-07-05): Initial IPv4 CIDR subnet calculator release.