CIDR / Subnet Calculator

Get network, broadcast, mask and host range from CIDR. Free, private and instant.

About the CIDR / Subnet Calculator

CIDR notation like 192.168.1.0/24 describes an IP range. The number after the slash says how many bits belong to the network.

When to use it

Use it to plan subnets, find the broadcast address, count usable hosts, or write firewall and cloud security rules.

Reading CIDR notation

In 192.168.1.0/24 the number after the slash counts the leading bits that identify the network. The remaining bits identify hosts, so a /24 leaves 8 host bits.

Usable hosts

A subnet has 2 to the power of its host bits in addresses, but the first (network) and last (broadcast) are reserved. A /24 gives 254 usable hosts and a /26 gives 62.

Private ranges

10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are reserved for private networks and are not routed on the public internet.

Planning tips

Choose a size that fits today with room to grow, avoid overlapping ranges between networks you may connect later, and document each subnet. Cloud providers often reserve a few extra addresses in every subnet.

How to use the CIDR / Subnet Calculator

1. Enter or paste your input in the fields above.
2. The result updates as you type, or press Run.
3. Press Copy to copy the output.

Frequently asked questions

Is the CIDR / Subnet Calculator free?

Yes. It is completely free, with no signup and no usage limits.

Is my data uploaded anywhere?

No. Everything runs locally in your browser, so what you type never leaves your device.

Does the CIDR / Subnet Calculator work on mobile?

Yes. The tool is responsive and works on phones, tablets and desktops.

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