CIDR to IP Range Explained

CIDR notation describes an IP network using an address and a prefix length.

Example:

10.0.0.0/24

The /24 means the first 24 bits identify the network. The remaining 8 bits are available for addresses inside that range.

For a quick conversion, use the CIDR to IP Range Calculator.

Example: 10.0.0.0/24

A /24 contains 256 total IPv4 addresses.

For 10.0.0.0/24:

FieldValue
Network address10.0.0.0
First usable IP10.0.0.1
Last usable IP10.0.0.254
Broadcast address10.0.0.255
Subnet mask255.255.255.0
Total IPs256
Classic usable hosts254

Classic IPv4 subnetting reserves the network and broadcast addresses.

Cloud platforms reserve additional addresses, so Azure, AWS, and Google Cloud usable counts are lower.

CIDR Prefix Size

The prefix controls the size of the range.

CIDRTotal IPsClassic usable hosts
/3042
/2986
/281614
/273230
/266462
/25128126
/24256254
/23512510
/2210241022
/2120482046
/2040964094

Every time the prefix gets one number smaller, the address space doubles.

CIDR to IP Range vs IP Range to CIDR

Use CIDR to IP range when you already have CIDR notation and want to see what it contains.

Use IP Range to CIDR when you have a start and end address and need the matching CIDR block list.

They are reverse operations:

  • 10.0.0.0/24 -> 10.0.0.0 - 10.0.0.255
  • 10.0.0.0 - 10.0.0.255 -> 10.0.0.0/24

Uneven ranges may require multiple CIDR blocks.