CIDR (Classless Inter-Domain Routing) is a method of allocating IP addresses and routing Internet Protocol packets.

What is the difference between IPv4 and IPv6?

IPv4 uses 32-bit addresses while IPv6 uses 128-bit addresses, providing a much larger address space.

How many usable IP addresses are available in a /24 subnet?

HostNamaste reserves one address for the network, one for the gateway and one for the broadcast address, leaving 253 usable IP addresses in a /24 subnet.

Does this calculator support IPv6?

Yes. The HostNamaste IP Calculator fully supports IPv4 and IPv6 CIDR calculations.

Free IPv4 & IPv6 CIDR, Subnet & Network Calculator

Trusted by thousands of hosting customers since 2016.

Instantly calculate IPv4 & IPv6 Network Address, CIDR Blocks, Subnet Masks, Gateway Addresses, Broadcast Addresses, IP Ranges and more.

IPv4 IPv6 CIDR Subnetting Network Calculator

IPv4

Network Calculator

IPv6

Prefix Calculator

RFC

Standards Compliant

100%

Free Tool

Understanding of IP Addressing

Learn how IPv4, IPv6, CIDR notation, subnet masks and IP addressing work through our detailed networking guide.

Read Complete Guide

Frequently Asked Questions

CIDR (Classless Inter-Domain Routing) is a method used to allocate IP addresses efficiently and reduce routing table sizes. It replaces the traditional Class A, B and C addressing system.

IPv4 uses 32-bit addresses while IPv6 uses 128-bit addresses, providing a vastly larger address space and eliminating IPv4 exhaustion.

HostNamaste reserves one address for the Network Address, one for the Broadcast Address and one for the Gateway Address. Therefore, usable addresses are calculated as Total Addresses - 3.

IPv6 does not use broadcast addresses. Gateway addresses are not defined by the subnet itself and are assigned by the network administrator.

Yes. The HostNamaste IPv4 & IPv6 CIDR Calculator is completely free to use without registration or limitations. It supports both IPv4 and IPv6 subnet calculations for network administrators, developers and IT professionals.

IPv4 CIDR Cheat Sheet

Quick reference for common IPv4 subnet sizes, total addresses and usable addresses.

CIDR	Subnet Mask	Total Addresses	Usable Addresses
/30	255.255.255.252	4	1
/29	255.255.255.248	8	5
/28	255.255.255.240	16	13
/27	255.255.255.224	32	29
/26	255.255.255.192	64	61
/25	255.255.255.128	128	125
/24	255.255.255.0	256	253
/23	255.255.254.0	512	509
/22	255.255.252.0	1024	1021
/21	255.255.248.0	2048	2045
/20	255.255.240.0	4096	4093
/19	255.255.224.0	8192	8189
/18	255.255.192.0	16384	16381
/17	255.255.128.0	32768	32765
/16	255.255.0.0	65536	65533

IPv6 Prefix Reference

Common IPv6 prefix lengths and their corresponding address space.

Prefix	Number of Addresses
/128	1
/127	2
/126	4
/120	256
/112	65,536
/96	2³²
/64	2⁶⁴
/56	2⁷²
/48	2⁸⁰
/32	2⁹⁶

HostNamaste Intellectual Property Notice

This IP Calculator is the sole Intellectual Property of HostNamaste.com. You may not copy, redistribute, modify, resell or publicly distribute this software or any portion of its source code without prior written authorization from HostNamaste. Unauthorized commercial or public use is strictly prohibited.

Related Networking Tools

IP Blacklist Checker

Check whether an IPv4 or IPv6 address is listed on major DNS blacklists.

Open Tool

WHOIS Lookup

Domain and IP WHOIS lookup tool.

Coming Soon

Reverse DNS Lookup

Lookup PTR records and reverse DNS entries.