Subnet Calculator

Calculate and visualize IP subnets.

Runs in your browser — your data never leaves your device

Visual Subnet Calculator

Click below to split and join subnets.

Subnet address	Range of addresses	Usable IPs	IpCount	Divide	Join
192.168.0.0/16	192.168.0.0 - 192.168.255.255	192.168.0.1 - 192.168.255.254	65534

Subnetting is the process of dividing a single large network into smaller, more manageable sub-networks. Our visual subnet calculator helps you plan IP address allocation, understand CIDR notation, and optimize your network topology with ease.

How Subnetting Works

Subnetting works by borrowing bits from the host portion of an IP address to create a network portion. For example, a /24 subnet mask means 24 bits are used for the network, leaving 8 bits for hosts, which provides 254 usable IP addresses. By adjusting the subnet mask, you can control how many devices are on each sub-network, improving routing efficiency and security.

Common Subnet Masks

Subnet masks are typically expressed in CIDR (Classless Inter-Domain Routing) notation. Common masks include /8 (255.0.0.0) for large enterprise networks, /16 (255.255.0.0) for medium-sized networks, /24 (255.255.255.0) for small office networks, and /32 for a single host. Understanding these masks is essential for proper network planning and troubleshooting.

Subnet mask cheat sheet →

Netmask, wildcard mask and usable hosts for every CIDR prefix from /0 to /32.

Frequently Asked Questions

What does the subnet calculator do?

It calculates network details from a CIDR notation or IP/subnet mask pair, including the network address, broadcast address, host range, host count, and wildcard mask.

How do I calculate a subnet?

Enter a CIDR (e.g., 192.168.1.0/24) or an IP address with subnet mask, and the tool instantly displays all network details including available hosts and address ranges.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation combines an IP address with a prefix length (e.g., /24) that indicates how many bits define the network portion. A /24 gives 256 addresses.

Can I use this for IPv6?

Yes. The tool supports IPv6 addresses and CIDR notation, calculating the address space, interface count, and network details for IPv6 subnets.

Is this calculator free?

Yes, ToolDock's subnet calculator is completely free, requires no signup, and runs entirely in your browser.

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How Subnetting Works

Common Subnet Masks

Frequently Asked Questions

What does the subnet calculator do?

How do I calculate a subnet?

What is CIDR notation?

Can I use this for IPv6?

Is this calculator free?

Related Tools

How Subnetting Works

Common Subnet Masks