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IPv4 CIDR Calculator

Enter an IPv4 address and prefix to see the whole network at a glance.

Enter an IPv4 address

IP address / prefix

Example: 192.168.1.10/24

What is a prefix?

The number after the slash is the number of network bits. A /24 uses 24 network bits; the remaining 8 bits give 256 addresses.

IPv4 only. Addresses reserved by your cloud provider are not deducted.

Network details

Network CIDR

192.168.1.0/24

Subnet mask: 255.255.255.0
Wildcard mask: 0.0.0.255
Network address: 192.168.1.0
Broadcast: 192.168.1.255
First host: 192.168.1.1
Last host: 192.168.1.254
Total addresses: 256
Usable hosts: 254

Host counts exclude network and broadcast addresses. This mathematical range does not indicate public address availability.

IPv4 CIDR Calculator · How it works

CIDR and address counts

IPv4 addresses contain 32 bits. For prefix p, the address count is 2^(32 − p): 256 for /24 and 65,536 for /16. Ordinary subnet host counts exclude the network and broadcast addresses. For example, 192.168.1.10/24 is normalized to 192.168.1.0/24.

/31, /32 and provider reservations

RFC 3021 allows both /31 addresses to be used on point-to-point links. A /32 represents one host; neither case has a broadcast address here. Cloud providers may reserve additional addresses. Check their policies and your equipment’s /31 support separately. The /0 total includes private, reserved and special-use addresses.

ReferencesRFC 3021