IP Subnet Calculator

Name: IP Subnet Calculator
Author: Jitendra Kumar

Calculate IPv4 and IPv6 CIDR ranges, network addresses, masks, usable host ranges, and subnet split previews.

Last Updated: May 2026

CIDR network

192.168.1.0/24

Usable hosts

254

Subnet mask

255.255.255.0

Address scope

Private RFC 1918

IPv4 address or CIDR

CIDR suffix in this field overrides the separate prefix input.

Prefix length

0 to 32

Split to prefix

Must be equal to or longer than the source prefix.

Subnet Details

Field	Value
Input address	192.168.1.42
Network address	192.168.1.0
Broadcast address	192.168.1.255
Wildcard mask	0.0.0.255
First usable	192.168.1.1
Last usable	192.168.1.254
Total addresses	256
Usable addresses	254

Notation

Notation	Value
CIDR	192.168.1.0/24
Subnet mask	255.255.255.0
Wildcard mask	0.0.0.255
IP binary	11000000.10101000.00000001.00101010
Mask binary	11111111.11111111.11111111.00000000

Subnet Split Preview

Showing the first 4 of 4 subnets at /26.

Subnet CIDR	Start address	Broadcast / end	Usable hosts
192.168.1.0/26	192.168.1.0	192.168.1.63	62
192.168.1.64/26	192.168.1.64	192.168.1.127	62
192.168.1.128/26	192.168.1.128	192.168.1.191	62
192.168.1.192/26	192.168.1.192	192.168.1.255	62

Networking Planning Notice

This calculator is a planning and education tool. Confirm production subnet plans against router, firewall, cloud, DHCP, and IP address management policies before deploying changes.

Reviewed For Methodology, Labels, And Sources

Every CalculatorWallah calculator is published with visible update labeling, linked source references, and founder-led review of formula clarity on trust-sensitive topics. Use results as planning support, then verify institution-, policy-, or jurisdiction-specific rules where they apply.

Reviewed By

Jitendra Kumar, Founder & Editorial Standards Lead, oversees methodology standards and trust-sensitive publishing decisions.

Review editor profile

Topic Ownership

Sales tax and tax-sensitive estimate tools, Education and GPA planning calculators, Health, protein, and screening-formula pages, Platform-wide publishing standards and methodology

See ownership standards

Methodology & Updates

Page updated May 2026. Trust-critical pages are reviewed when official rates or rules change. Evergreen calculator guides are checked on a recurring quarterly or annual cycle depending on topic volatility.

Sources & methodology About the review process

How to Use the IP Subnet Calculator

Enter an IPv4 or IPv6 address with a CIDR prefix, such as 192.168.1.42/24 or 2001:db8:abcd:12::1/64. You can also enter the prefix in the separate prefix field.

Use the split-to-prefix field to preview smaller subnets inside the current network. The table shows the first few resulting subnet blocks.

Step 1: Choose IP version
Select IPv4 for dotted-decimal subnet masks or IPv6 for 128-bit prefix ranges.
Step 2: Enter address and prefix
Use CIDR notation or enter the address and prefix length separately.
Step 3: Review range details
Check the network address, end address, usable range, mask, wildcard, and address count.
Step 4: Preview smaller subnets
Set a longer split prefix to see the first subnet blocks inside the selected prefix.

How This IP Subnet Calculator Works

For IPv4, the calculator converts the dotted-decimal address into a 32-bit integer, applies the CIDR mask, and derives the network, broadcast, wildcard, first usable, last usable, and host count. Private address labels follow the common RFC 1918 ranges.

For IPv6, it parses compressed or expanded IPv6 notation into a 128-bit value, applies the prefix length, and reports the resulting prefix range. IPv6 does not have broadcast addresses, so the calculator reports the last address in the prefix instead.

The subnet split preview increases the prefix length, calculates the block size for each child prefix, and lists the first resulting subnets inside the parent network.

IP Subnetting Guide

Core Subnet Formulas

Item	Formula or rule	Meaning
CIDR prefix	Address/prefix-length	The prefix length counts the leftmost bits that form the network prefix.
Subnet mask	Prefix bits set to 1, host bits set to 0	IPv4 masks are displayed in dotted decimal, such as 255.255.255.0.
Wildcard mask	Inverse of the subnet mask	Common in ACLs and route matching, especially with IPv4.
Network address	IP address AND subnet mask	The first address in the prefix block.
IPv4 usable hosts	2^(32 - prefix) - 2 for /0 through /30	/31 point-to-point and /32 host routes use special handling.

Common Prefix Examples

Prefix	Mask or bit split	Typical use
IPv4 /24	255.255.255.0	256 total, 254 typical usable hosts
IPv4 /30	255.255.255.252	4 total, 2 typical usable hosts
IPv4 /31	255.255.255.254	2 addresses for point-to-point links
IPv4 /32	255.255.255.255	Single host route
IPv6 /64	64 network bits	Common LAN subnet size
IPv6 /128	128 network bits	Single IPv6 address

IPv4 vs IPv6 Subnet Results

IPv4 subnet calculators usually emphasize subnet masks, wildcard masks, broadcast addresses, and usable hosts because those values are common in LAN, firewall, and routing work.

IPv6 subnetting is prefix-based. A /64 can contain a very large number of interface identifiers, and IPv6 addressing does not reserve a broadcast address in the same way IPv4 does.

Keep the research moving with Data Storage Converter, Password Generator, Numbers Converter, and Scientific Calculator.

Frequently Asked Questions

It converts an IP address and CIDR prefix into the network address, address range, mask details, usable host count, and smaller subnet previews.

CIDR notation writes an address followed by a slash and prefix length, such as 192.168.1.10/24 or 2001:db8::1/64. The prefix length tells how many leftmost bits are the network prefix.

IPv4 subnets traditionally reserve an all-ones host address as directed broadcast. IPv6 does not use broadcast; multicast and other mechanisms handle that role.

RFC 3021 allows 31-bit prefixes on point-to-point links where the two addresses represent the two link endpoints rather than a network and broadcast pair.

It labels common private, loopback, link-local, multicast, and related scopes, but routing policy depends on your network and upstream providers.