IP Subnet Calculator

Runs on your device. Nothing is sent.Nothing is sent anywhere - every calculation runs on your device, even offline.

IP address with prefix or maskType a prefix (/24), a subnet mask (255.255.255.0) or a wildcard mask (0.0.0.255) after the address. IPv6 works too.

Prefix

Examples

Results

Private (RFC 1918)

IP address: 192.168.1.10
Network: 192.168.1.0/24
Subnet mask: 255.255.255.0
Wildcard mask: 0.0.0.255
Broadcast address: 192.168.1.255
First usable host: 192.168.1.1
Last usable host: 192.168.1.254
Usable hosts: 254
Total addresses: 256
Address type: Private (RFC 1918)
Class (historic): C
Hexadecimal: 0xC0A8010A
Integer: 3232235786
Reverse DNS (PTR) name: 10.1.168.192.in-addr.arpa

In binary

IP address11000000.10101000.00000001.00001010

Subnet mask11111111.11111111.11111111.00000000

Network11000000.10101000.00000001.00000000

Broadcast address11000000.10101000.00000001.11111111

Network bits (24)Host bits (8)

Split into subnets

Number of subnets

New prefix

Subnets: 4 × /26 · usable hosts in each: 62

#	Subnet	Usable range	Broadcast	Hosts
1	192.168.1.0/26	192.168.1.1 – 192.168.1.62	192.168.1.63	62
2	192.168.1.64/26	192.168.1.65 – 192.168.1.126	192.168.1.127	62
3	192.168.1.128/26	192.168.1.129 – 192.168.1.190	192.168.1.191	62
4	192.168.1.192/26	192.168.1.193 – 192.168.1.254	192.168.1.255	62

Is it in this network?

IP address or subnet to check

IPv4 and IPv6 subnet calculator: network, broadcast, host range, masks and binary, plus subnet splitting and VLSM. Runs in your browser.

A subnet calculator takes an IP address and its prefix length or mask and works out the network it belongs to: the network and broadcast addresses, the first and last usable host, how many hosts fit, the subnet and wildcard masks and the binary behind them. Gizke.com's calculator handles IPv4 and IPv6, reads CIDR (/24), dotted masks and Cisco wildcard masks, tells private, CGNAT, link-local and other special ranges apart, splits a network into equal subnets or into subnets sized for a list of host counts (VLSM), and checks whether an address or subnet falls inside it. Everything runs in your browser and keeps working offline.

Frequently asked questions

Why does a /24 have 254 usable hosts and not 256?

A /24 has 256 addresses, but the first one is the network address and the last one is the broadcast address, so neither can be given to a device. That leaves 254. In general an IPv4 subnet has 2^(32 - prefix) addresses and 2 fewer usable hosts.

How are /31 and /32 handled?

A /31 holds two addresses and, following RFC 3021, both are usable on a point-to-point link between two routers - there is no network or broadcast address to set aside. A /32 is a single address, used for loopbacks and host routes. Calculators that report 0 usable hosts for a /31 apply the old rule that predates RFC 3021.

What is a wildcard mask?

It is the subnet mask with every bit flipped: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match. You can type either one after the address and the calculator works out the prefix.

Why is 010.1.1.1 rejected?

Some software reads a leading zero as octal, so 010 means 8, while other software reads it as decimal 10. The same text can therefore point at two different networks. Rather than guess, the calculator asks you to write the number without leading zeros.

How does VLSM splitting work?

Variable-length subnet masking gives each subnet only as many addresses as it needs. Enter the hosts each subnet needs; each one gets the smallest block that fits (hosts plus network and broadcast), and blocks are placed from largest to smallest so each starts on its own boundary and nothing overlaps.

Is my IP address sent anywhere?

No. All the maths runs in your browser with no server involved, so the page also works offline. A link you copy carries the input in the address after ?q=, so only share it with people who may see that network.