CIDR / Subnet Calculator

Calculate IPv4 network details from CIDR notation, including network and broadcast addresses, subnet mask, usable hosts, and address ranges.

IPv4 address / CIDRIPv4 only. Example: 192.168.1.10/24

Example presets

Tap one to fill the input quickly.

Changing the input clears the previous result so Copy always uses the latest calculation.

Result

Subnet details

Paste a CIDR block such as 192.168.1.10/24 to calculate the IPv4 network range.

Enter an IPv4 address and CIDR prefix, then click Calculate to see the subnet details.

Deep dive

More context for CIDR / Subnet Calculator

Useful when you need to translate a CIDR block into network boundaries, subnet masks, and usable IP ranges.

Overview

What is this tool?

It converts an IPv4 address and CIDR prefix into network details such as the CIDR notation, subnet mask, broadcast address, usable IP range, and address counts.

Input samples

Example inputs

Small office subnet

Input: 192.168.1.10/24
Output: Network 192.168.1.0, broadcast 192.168.1.255, usable IP range 192.168.1.1-192.168.1.254

Larger private range

Input: 10.0.0.0/16
Output: Subnet mask 255.255.0.0, 65,536 total addresses, 65,534 usable hosts

Tighter host block

Input: 172.16.5.34/27
Output: Network 172.16.5.32, broadcast 172.16.5.63, usable IP range 172.16.5.33-172.16.5.62

When to use it

Common use cases

Plan a lab or office subnet before assigning addresses or VLANs.
Check whether an IP belongs to the CIDR block you expect.
Confirm subnet mask, usable IP range, broadcast, and network boundaries quickly.

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Answers

FAQ

Does it support IPv6?

No. This calculator is IPv4 only.

What is CIDR notation?

CIDR notation combines an IPv4 address with a prefix length, such as `192.168.1.10/24`, to describe the network block and mask.

What is a CIDR block?

A CIDR block is the address range described by the prefix, including the network address, broadcast address, and usable host range where applicable.

What happens with /31 and /32 prefixes?

They follow IPv4 subnet math, which can leave no traditional usable host range.

How do I find the usable IP range?

The tool calculates the first and last usable host addresses for the CIDR block so you can avoid assigning the network or broadcast address by mistake.

Can I paste only a CIDR prefix?

No. The tool expects an IPv4 address together with the prefix, such as `192.168.1.10/24`.