e.g. 192.168.1.0/24
Subnet Calculator - CIDR Calculator
Domain Input
Subnet Calculator — CIDR & IP Range
Calculate network address, broadcast address, host range, and usable hosts from any IP/CIDR notation. The reference table shows all IPv4 subnet sizes from /0 to /32 with mask and host count. Essential for network planning, firewall rule design, and IP address management.
How It Works
Enter an IP address with CIDR prefix length (e.g. 192.168.1.0/24). The calculator performs bitwise operations to derive the network address, broadcast address, first/last usable host, and wildcard mask. All computation runs client-side in your browser — no data is sent to any server.
FAQ
What does /24 mean in CIDR notation?
The number after the slash indicates how many bits are used for the network portion. /24 means the first 24 bits are the network (255.255.255.0 mask), leaving 8 bits for hosts — that's 254 usable addresses (256 minus network and broadcast).
How many hosts can a /16 subnet hold?
A /16 subnet has 16 host bits, giving 65,534 usable addresses (2^16 − 2). The subtraction accounts for the network address and broadcast address which cannot be assigned to hosts.
What is the difference between subnet mask and wildcard mask?
A subnet mask marks network bits with 1s and host bits with 0s (e.g. 255.255.255.0). A wildcard mask is the bitwise inverse — host bits are 1s and network bits are 0s (e.g. 0.0.0.255). Wildcard masks are used in ACLs and routing protocols like OSPF.