Subnet calculator

Enter an IPv4 address and CIDR prefix to get the full subnet picture: network and broadcast addresses, wildcard mask, usable host range, and capacity.

How to Subnet calculator

1. Step 1. Enter an IPv4 address (e.g. 192.168.1.130).
2. Step 2. Drag the CIDR slider (or enter a prefix like /26).
3. Step 3. Review network, broadcast, host range, and masks.
4. Step 4. Check the binary view for mask alignment.

Frequently asked questions

What does /24 mean?

The first 24 bits of the address are the network portion, giving a 255.255.255.0 mask with 254 usable hosts.

Why are usable hosts 2 less than total?

The network address (all host bits 0) and broadcast address (all host bits 1) cannot be assigned to hosts — except in /31 and /32 special cases.

What is a wildcard mask?

The inverse of the subnet mask, used in ACLs and OSPF network statements: 0.0.0.255 for a /24.