IP Subnet Calculator | IPv4 & IPv6 Subnet, CIDR & Mask Tool

IPv4 Subnet Calculator

Enter an IPv4 address and a CIDR prefix or subnet mask. Results update as you type.

IPv4 Address

CIDR / Subnet Mask

CIDR /24 (255.255.255.0)

Network Address

192.168.1.0

Broadcast Address

192.168.1.255

Usable Host Range

192.168.1.1 – 192.168.1.254

Total / Usable Hosts

256 / 254

Subnet Mask

255.255.255.0

CIDR

/24

Wildcard Mask

0.0.0.255

IP Class

Address Type

Private (192.168.0.0/16)

IP binary11000000.10101000.00000001.00000001

Mask binary11111111.11111111.11111111.00000000

Network binary11000000.10101000.00000001.00000000

Tip: Bold bits are the network portion. Usable hosts = 2^{(32 − CIDR)} − 2, except /31 (2 hosts) and /32 (1 host).

IPv6 subnet calculator

IPv6 Subnet Calculator

Enter an IPv6 address and a prefix length to find the network, address range and size.

IPv6 Address

Prefix Length (CIDR)

Prefix /64

Network Prefix

2001:db8::/64

First Address

2001:db8::

Last Address

2001:db8::ffff:ffff:ffff:ffff

Total Addresses

2^64 (18,446,744,073,709,551,616)

Number of /64 Subnets

Expanded Address

2001:0db8:0000:0000:0000:0000:0000:0001

Tip: IPv6 has no broadcast address. Total addresses = 2^{(128 − prefix)}, and a /64 is the standard size for a single network.

IP Subnet Calculator — Free IPv4 and IPv6 Subnet, CIDR and Mask Calculator on HighCalc

IP Subnet Calculator: Calculate IPv4 & IPv6 Networks Easily

Our free online IP Subnet Calculator helps you quickly calculate IPv4 and IPv6 subnet details, including the network address, broadcast address, CIDR notation, subnet mask, usable host range, binary conversion, prefix length and IP ranges. It supports both IPv4 and IPv6, which makes it useful for network engineers, IT professionals, students, cybersecurity analysts and server administrators.

Quick answer: the address 192.168.1.1 with a /24 mask is in the network 192.168.1.0, the broadcast address is 192.168.1.255, and the 254 usable hosts run from 192.168.1.1 to 192.168.1.254. Enter your own address and CIDR or subnet mask above to see the details instantly.

What Is IP Subnetting?

IP subnetting is the process of dividing a larger network into smaller subnetworks, called subnets. It improves network organization, performance, security and efficient use of IP addresses. A subnet helps devices communicate within a network while reducing unnecessary traffic, and it is widely used in routers, switches, enterprise networks, cloud infrastructure, internet service providers and data centers. Every subnet has a network address, a broadcast address (in IPv4), a usable host range, a subnet mask and a CIDR prefix.

What Is IPv4?

IPv4 (Internet Protocol version 4) is the most widely used internet addressing system. It uses 32-bit addresses written in dotted decimal format, such as 192.168.1.1. IPv4 subnetting uses subnet masks and CIDR notation, with common masks like 255.255.255.0, 255.255.0.0 and 255.0.0.0. Private networks use the ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16, while public addresses are routable on the internet.

What Is CIDR?

CIDR stands for Classless Inter-Domain Routing. CIDR notation, such as /24, /16 or /64, says how many bits belong to the network portion of an address. A smaller number gives a larger network and a bigger number gives a smaller one. It replaced the old class A, B and C system and improves address allocation and routing across the internet. The table shows common IPv4 prefix lengths.

CIDR	Subnet mask	Total addresses	Usable hosts
/8	255.0.0.0	16,777,216	16,777,214
/16	255.255.0.0	65,536	65,534
/24	255.255.255.0	256	254
/25	255.255.255.128	128	126
/26	255.255.255.192	64	62
/27	255.255.255.224	32	30
/28	255.255.255.240	16	14
/29	255.255.255.248	8	6
/30	255.255.255.252	4	2
/31	255.255.255.254	2	2
/32	255.255.255.255	1	1

A /31 is used for point-to-point links and has two usable addresses, and a /32 identifies a single host.

What Is IPv6?

IPv6 (Internet Protocol version 6) is the newer addressing system created to solve IPv4 address exhaustion. It uses 128-bit hexadecimal addresses such as 2001:db8::1, offering a vast number of addresses and better routing efficiency. Most IPv6 networks use a /64 prefix for each subnet, which supports automatic address configuration (SLAAC). IPv6 is widely used in cloud computing, internet service providers, data centers, IoT devices and enterprise networks. Unlike IPv4, it has no broadcast address.

Who Uses an IP Subnet Calculator?

Network engineers, system administrators, IT professionals, cybersecurity analysts, cloud and DevOps engineers, CCNA and Network+ students, internet service providers, server administrators, data center technicians, web hosting companies and software developers all use it. It simplifies complex calculations, reduces networking mistakes, saves time when configuring routers and switches, and helps with network planning. For converting between number systems, the binary calculator is a useful companion.

How to Use This IP Subnet Calculator

Enter an IP address

For example 192.168.1.1, 10.0.0.1 or 2001:db8::1.

Enter the CIDR or subnet mask

Use CIDR like /24 or a mask like 255.255.255.0. For IPv6, enter the prefix length such as /64.

Click Calculate

The results also update as you type or move the slider.

Read the results

See the network address, broadcast address, usable host range, total hosts, subnet mask, binary form, IPv6 prefix details and address ranges.

Features

IPv4 and IPv6

Both protocols on one page

Masks and CIDR

Enter a prefix or a subnet mask

Host Ranges

Network, broadcast, first and last usable address

Binary View

Network bits highlighted in the binary form

Works Everywhere

Fully responsive on phone, tablet, and desktop

Private & Secure

All calculations run in your browser — nothing is sent anywhere

Frequently Asked Questions

Common questions about the IP Subnet Calculator.

What is an IP subnet calculator?

An IP subnet calculator is a networking tool that works out the subnet mask, CIDR range, network address, broadcast address and usable host range for an IPv4 or IPv6 network. It saves time and avoids mistakes when planning or configuring networks.

What is CIDR notation, and what does /24 mean?

CIDR stands for Classless Inter-Domain Routing. It writes how many bits of an address belong to the network, such as /24. A /24 means the first 24 bits are the network and 8 bits are left for hosts, which gives 256 addresses and 254 usable hosts.

How many hosts are in a /24 subnet?

A /24 has 256 addresses in total. The first is the network address and the last is the broadcast address, so 254 are usable. The formula for usable hosts is 2^(32 − prefix) − 2.

What is the difference between IPv4 and IPv6 subnetting?

IPv4 uses 32-bit addresses in dotted decimal and needs subnet masks or CIDR to separate network and host bits. IPv6 uses 128-bit hexadecimal addresses written with colons, has no broadcast address and normally uses /64 for each network.

Why does IPv6 use /64 for most networks?

A /64 leaves 64 bits for the interface identifier, which is what stateless address autoconfiguration (SLAAC) needs. It also gives each network about 18 quintillion addresses, so there is no need to conserve them inside a subnet.

What are the network, broadcast and first and last usable addresses?

The network address identifies the subnet itself, and the broadcast address (IPv4 only) reaches every device in it. Neither can be assigned to a device. The first usable address is the one after the network address, and the last is the one before the broadcast address.