Subnet Ninja The Ultimate Subnet Calculator
A fast, accurate, and mobile-friendly tool for networking professionals. Easily calculate IPv4 and IPv6 subnets, wildcards, and host ranges.
How to use the subnet calculator
- Enter an IPv4 or IPv6 address, for example 192.168.1.100.
- Enter a CIDR prefix (/24) or, for IPv4, a dotted subnet mask (255.255.255.0).
- Select Calculate Subnet to see the network and broadcast address, host range, wildcard mask and usable hosts. The results page has its own link that you can bookmark or share.
Input examples
- 192.168.1.100 /24: IPv4 with a CIDR prefix
- 10.0.0.5 255.0.0.0: IPv4 with a subnet mask
- 2001:db8:: /64: IPv6 with a prefix length
What is a subnet mask?
A subnet mask marks which part of an IPv4 address is the network and which part is the host. A /24 mask, 255.255.255.0, leaves 8 host bits: 256 addresses, of which 254 are usable hosts. See the /24 subnet mask or every prefix in the subnet cheat sheet.
What is CIDR notation?
CIDR notation writes the mask as a prefix length after a slash, such as 10.0.0.0/8, where 8 is the number of network bits (RFC 4632). Learn the method step by step in how to subnet.