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IP Subnet Calculator

Enter an IPv4 address in CIDR notation and see the network, broadcast, mask, host range, and host count.

Accepts CIDR like 192.168.1.10/24 or an address and mask like 192.168.1.10 255.255.255.0. Everything runs in your browser.

Prefix length/24 · 255.255.255.0
/0/32

Subnet breakdown

Subnet mask in binary
11111111.11111111.11111111.00000000

How to calculate an IPv4 subnet online

  1. Enter the IP address

    Type an IPv4 address with a prefix, such as 192.168.1.10/24, or paste an address followed by a dotted subnet mask.

  2. Adjust the prefix length

    Drag the prefix length slider from /0 to /32 to resize the subnet, or type a mask like 255.255.255.0 to set it exactly.

  3. Read and copy the results

    The network, broadcast, mask, wildcard, host range, and host counts update instantly. Click any value to copy it, or copy the full summary.

Why use this tool

Full subnet breakdown

Network address, broadcast, subnet mask, wildcard mask, first and last usable host, total addresses, and usable host count, all shown together.

CIDR or dotted mask

Enter a prefix such as /24 or a dotted subnet mask such as 255.255.255.0. The calculator reads either form and keeps the two in sync.

Live prefix slider

Drag the prefix length from /0 to /32 and watch every value, including the usable host count, recalculate instantly.

Address class and type

See the classful range from A to E and whether the address is private, public, loopback, link-local, or multicast.

Copy any value

Click a result card to copy just that address or number, or copy the entire subnet summary as plain text in a single click.

Runs entirely in your browser

Everything is calculated on your device. Nothing you enter is uploaded or logged.

About this tool

This IPv4 subnet calculator turns an address and prefix length into a complete picture of the network it belongs to. Enter something like 192.168.1.10/24, or an address followed by a dotted subnet mask, and it computes the network address, broadcast address, subnet mask, wildcard mask, the first and last usable host, the total number of addresses, and how many of those can be assigned to hosts. Every value updates the moment you change the address or drag the prefix length slider.

Subnetting is really just arithmetic on the 32 bits of an address, so the calculator handles the full range from /0 to /32, including the point-to-point /31 and single-host /32 cases that trip up simpler tools. It reads both CIDR notation and dotted masks, checks that each octet is between 0 and 255, and confirms that a typed mask is contiguous before using it. It also labels the classful range and reports whether the address is private, public, loopback, or link-local.

Reach for it when planning an address scheme, sizing a VLAN, writing a firewall rule, or double-checking what a /26 actually covers. Because a mask is just a run of ones followed by zeros, the number base converter pairs well with it when you want to see those bits in binary or hexadecimal. Everything runs in your browser, so the addresses you enter never leave your device.

Frequently asked questions

How do I use the subnet calculator?
Enter an IPv4 address with a prefix, for example 192.168.1.10/24, or an address and a dotted subnet mask. The network, broadcast, mask, host range, and host counts appear instantly and keep updating as you edit.
What is the difference between usable hosts and total addresses?
Total addresses is every address in the block, which is 2 raised to the number of host bits. Usable hosts leaves out the network and broadcast addresses, so it is two fewer, except for /31 and /32 subnets where every address is usable.
Does it support CIDR and dotted subnet masks?
Yes. You can type a prefix such as /24 or a dotted mask such as 255.255.255.0, and the two stay in sync. A mask has to be contiguous, and each octet must be between 0 and 255.
Does it handle /31 and /32 subnets?
Yes. A /31 is treated as a two-address point-to-point link with both addresses usable, and a /32 is a single host. Prefix lengths from /0 to /32 are all supported.
Does it work with IPv6?
This tool covers IPv4 only. IPv6 uses a different and much larger address format that is not calculated here.
Is my data uploaded anywhere?
No. Everything runs in your browser; nothing you enter is sent to a server or stored.

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