What is the difference between subnet mask and wildcard mask?

The subnet mask has 1s in the network portion and 0s in the host portion (e.g. 255.255.255.0 for /24). The wildcard mask is its bitwise inverse — 0s for network bits and 1s for host bits (e.g. 0.0.0.255) — and is commonly used in Cisco ACLs and OSPF configurations.

Why are two host addresses unusable?

In a standard IPv4 subnet, the first address is reserved as the network address and the last is the broadcast address. For example, in 192.168.1.0/24 the addresses 192.168.1.0 and 192.168.1.255 are reserved, leaving 254 usable host addresses. /31 and /32 prefixes are special cases used for point-to-point links and host routes.

Can I use this for IPv6?

This tool currently supports IPv4 CIDR only. IPv6 subnetting uses the same prefix-length concept but operates on 128-bit addresses, which requires a separate calculation tool.

CIDR Subnet Visualizer & Calculator

NEW

Enter any IPv4 CIDR block such as 192.168.1.0/24 and instantly see the network address, broadcast address, usable host range, total and usable host counts, subnet mask in dotted-decimal and binary, and wildcard mask — with a colour-coded bit-level visualisation.

IPv4 CIDR notation

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How to use CIDR Subnet Visualizer

Type an IPv4 CIDR address into the input field, for example 10.0.0.0/16 or 172.16.5.64/26.
Press Calculate or just keep typing — the tool updates live as soon as it detects a valid CIDR.
Read the network address, broadcast, host range, masks, and host counts from the results table, and inspect the colour-coded bit map below.

What is CIDR Subnet Visualizer?

CIDR (Classless Inter-Domain Routing) notation compactly represents an IP network by combining an IP address with a prefix length (e.g. /24). The prefix length defines how many leading bits are the network portion and how many are the host portion. Understanding this is fundamental to subnetting, firewall rules, routing tables, and VPC configuration in cloud environments.

This calculator derives every key property of the subnet directly in your browser with no server round-trips. The bit-map visualisation colour-codes each of the 32 bits blue for network bits and grey for host bits, making it immediately clear how the prefix length divides the address space.

FAQ

What is the difference between subnet mask and wildcard mask?: The subnet mask has 1s in the network portion and 0s in the host portion (e.g. 255.255.255.0 for /24). The wildcard mask is its bitwise inverse — 0s for network bits and 1s for host bits (e.g. 0.0.0.255) — and is commonly used in Cisco ACLs and OSPF configurations.
Why are two host addresses unusable?: In a standard IPv4 subnet, the first address is reserved as the network address and the last is the broadcast address. For example, in 192.168.1.0/24 the addresses 192.168.1.0 and 192.168.1.255 are reserved, leaving 254 usable host addresses. /31 and /32 prefixes are special cases used for point-to-point links and host routes.
Can I use this for IPv6?: This tool currently supports IPv4 CIDR only. IPv6 subnetting uses the same prefix-length concept but operates on 128-bit addresses, which requires a separate calculation tool.

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Last updated: 2026-06-02

CIDR Subnet Visualizer & Calculator

Subnet mask bit map

How to use CIDR Subnet Visualizer

What is CIDR Subnet Visualizer?

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