IPv4 Subnet Calculator
Get the network, broadcast, host range, subnet and wildcard mask for any IPv4 address and prefix.
Subnetting in seconds
Enter an IP address and prefix (e.g. 192.168.1.10/24) and the Subnet Calculator shows all the key network information instantly. Essential for network design, firewall rules, VLAN planning and certification exam prep.
Calculated values
- Network and broadcast address
- First and last usable host
- Total and usable host count
- Subnet mask and wildcard mask (with binary notation)
- IP class and whether the address is private, public or reserved
Easier learning
The binary notation of the masks helps you visualise subnetting. The wildcard mask needed for Cisco ACLs is calculated automatically.
How to use IPv4 Subnet Calculator
- Enter the IPv4 address.
- Set the prefix length (/24) or subnet mask.
- Review the network, broadcast and host range.
- Copy the values you need.
Why use this tool?
Gives correct subnet information without binary maths by hand and prevents network misconfiguration.
FAQ
Why does a /24 have 254 usable hosts, not 256?
The first address is the network and the last is the broadcast address, so 2 of the 256 can't be assigned to hosts.
What is a wildcard mask?
The inverse of the subnet mask, used in Cisco ACL and OSPF configuration. For /24 it's 0.0.0.255.
Why aren't 192.168.x.x addresses visible on the internet?
They're private addresses defined in RFC 1918 and only used on local networks.
Related tools
CIDR Calculator
Convert a CIDR prefix to a subnet mask, count addresses and split a network into smaller blocks.
Open toolIP Range to CIDR Calculator
Count the addresses between two IPv4 addresses and turn the range into the smallest CIDR list.
Open toolIP to Binary Converter
Convert IPv4 addresses to dotted binary and back, with hex and 32-bit integer forms.
Open toolPort Number Lookup
Look up common TCP and UDP port numbers by number or service name, e.g. 22 SSH, 443 HTTPS.
Open tool