IP subnet calculator
Calculate subnet details from an IP address and CIDR prefix. Shows network address, broadcast, host range, wildcard mask and usable hosts.
- Free, no sign-up
- No data stored
- Reviewed 2026-01-15
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About the IP Subnet Calculator
Enter an IPv4 address with a CIDR prefix length (e.g. 192.168.1.0/24) to see full subnet details: network address, broadcast address, first and last usable host, subnet mask, wildcard mask and total host count.
How to use the IP Subnet Calculator
- Enter an IP address.
- Set the CIDR prefix (e.g. /24).
- View network, broadcast, host range and mask.
Frequently asked questions
What does /24 mean?
The first 24 bits are the network portion. This leaves 8 bits for hosts = 254 usable addresses (256 minus network and broadcast).
What is a wildcard mask?
The inverse of the subnet mask. Used in access control lists (ACLs) on Cisco routers. For /24: subnet mask 255.255.255.0, wildcard 0.0.0.255.
Does this support IPv6?
Currently IPv4 only. IPv6 subnetting uses the same CIDR concept but with 128-bit addresses.