What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation combines an IP address with a prefix length separated by a slash, for example 192.168.0.0/16. The prefix length specifies how many leading bits are the network part; the remaining bits identify individual hosts.

What is the difference between total addresses and usable hosts?

Every subnet reserves the first address as the network address and the last as the broadcast address. Usable hosts = total addresses - 2. For a /32 (single host) and /31 (point-to-point link) the convention differs, but this tool shows the mathematical total.

Does this support IPv6?

This tool handles IPv4 CIDR blocks (/0 through /32). IPv6 support requires 128-bit integer arithmetic and is not included in the current version.

What does a /32 mean?

A /32 prefix means all 32 bits are network bits, so the block contains exactly one IP address. It is commonly used to define a single host route in routing tables or firewall rules.

Can I enter a host address instead of a network address?

Yes. For example, 192.168.1.5/24 will be normalized to the network 192.168.1.0/24 and all values will be calculated from that network address.

CIDR to IP Range Converter

Name: CIDR to IP Range Converter
Availability: InStock
Author: Nham Vu

Enter a CIDR block and instantly see the start IP, end IP, netmask, broadcast address, and total host count.

CIDR Block

Quick examples:

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Enter a CIDR block on the left to see the full range breakdown.

CIDR Block

Network Address

Broadcast Address

First Usable Host

Last Usable Host

Subnet Mask

Wildcard Mask

Prefix Length

Total Addresses

Usable Hosts

IP Class: Binary prefix:

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Summary

Enter a CIDR block and instantly see the start IP, end IP, netmask, broadcast address, and total host count.

How it works

Enter a CIDR block such as 192.168.1.0/24 in the input field.
The tool parses the IP address and prefix length from the notation.
It calculates the network mask by setting the top N bits (where N is the prefix length).
The start IP is derived by ANDing the address with the mask; the end IP by ORing with the inverted mask.
Host count, netmask, broadcast, and usable host range are displayed instantly.
You can also look up multiple CIDRs one at a time using the history list.

Use cases

Verify firewall or security-group rules cover the right IP range.
Plan subnet allocations for a VPC or on-premises network.
Convert CIDR blocks from cloud provider documentation to human-readable ranges.
Debug network routing issues by confirming address boundaries.
Teach or learn subnetting and CIDR notation concepts.
Quickly check how many hosts fit in a given prefix.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu