ToolStack

CIDR Calculator

Expand a CIDR block into its network, mask, wildcard and host range.

100% private — everything runs in your browser

How to Use

  1. 1

    Type an IPv4 CIDR block, for example 10.0.0.0/16.

  2. 2

    Review the mask, broadcast and host range.

  3. 3

    Optionally test an address to see whether it belongs to the block.

Examples

Typical home subnet

Input

192.168.1.0/24

Output

Mask 255.255.255.0, usable hosts 192.168.1.1 – 192.168.1.254 (254 hosts).

Large private block

Input

10.0.0.0/8

Output

Mask 255.0.0.0, 16,777,214 usable hosts across 10.0.0.0 – 10.255.255.255.

FAQ

Why is the host count not the total addresses?

The network and broadcast addresses cannot be assigned to hosts, so /24 has 254 usable addresses, not 256.

Does it support IPv6?

No. This calculator is IPv4 only, where subnetting arithmetic is most commonly needed.

How is the address class determined?

Class A starts at 1, class B at 128, class C at 192, class D at 224 and class E at 240.

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