Subnet Calculator

Calculate IPv4 subnet details from an IP address and CIDR prefix or subnet mask.

/ or
Network Address
Broadcast Address
Usable Host Range
Subnet Mask
Wildcard Mask
Total Addresses
Usable Hosts
CIDR Notation
IP Class
Binary Subnet Mask

CIDR Reference Table

CIDRSubnet MaskAddressesUsable Hosts

How Subnetting Works

Subnetting divides a network into smaller subnetworks. The subnet mask determines which portion of an IP address identifies the network vs. the host.

Frequently Asked Questions

What is CIDR notation? CIDR (Classless Inter-Domain Routing) uses /prefix to denote the number of network bits. /24 means 24 network bits and 8 host bits = 256 addresses.

Why do I lose 2 addresses? The first address is the network address and the last is the broadcast address. Neither can be assigned to a host.

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