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Subnet Calculator
Free IPv4 subnet calculator. Enter an IP and CIDR to get network address, broadcast, usable range, subnet mask, and host count. 100% client-side and.
How to use
Enter IP & CIDR — Type an IP address and choose the CIDR prefix (e.g., 192.168.1.0 / 24).
Review Subnet Info — See network address, broadcast, usable range, subnet mask, and total hosts.
Copy Values — Click the copy button next to any value to paste it into your config or documentation.
Free Online Subnet Calculator (IPv4 CIDR)
Calculate network addresses, broadcast addresses, usable IP ranges, subnet masks, and host counts from any IPv4 address and CIDR prefix. The tool uses bitwise operations for instant, accurate results — all processed locally in your browser.
What This Calculator Shows
Network Address: The first address in the subnet, identifying the network itself.
Broadcast Address: The last address in the subnet, used to send data to all hosts.
Usable Range: The first and last IP addresses that can be assigned to devices.
Total / Usable Hosts: Total addresses minus reserved network and broadcast addresses.
Subnet Mask: The dotted-decimal mask corresponding to the CIDR prefix.
Wildcard Mask: The inverse mask used in Cisco ACLs and routing protocols.
Binary Mask: The 32-bit binary representation of the subnet mask.
Common CIDR Prefixes
/8 — 16,777,216 hosts (large enterprise, Class A equivalent)
/16 — 65,536 hosts (medium organization, Class B equivalent)
/24 — 256 hosts, 254 usable (standard small office/home)
/30 — 4 hosts, 2 usable (point-to-point WAN links)
/32 — 1 host (loopback or single-host assignment)
Privacy
All calculations run entirely in your browser. No IP addresses or network data are transmitted to any server.
CIDR (Classless Inter-Domain Routing) notation represents an IP address and its network prefix. /24 means the first 24 bits are the network portion, leaving 8 bits for hosts — equivalent to 255.255.255.0.
Why are total hosts and usable hosts different?
In traditional subnets, the network address (first) and broadcast address (last) are reserved, reducing usable hosts by 2. For /31 and /32 subnets, RFC 3021 allows using both addresses for point-to-point links.
Can I calculate IPv6 subnets?
This tool supports IPv4 only. IPv6 subnetting uses 128-bit addresses and /64 as the standard subnet size for end-user networks.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask, used in Cisco ACLs and some routing protocols. Where a subnet mask has 1s for the network, a wildcard mask has 0s.
Is my IP sent anywhere?
No. All calculations happen locally in your browser using pure JavaScript bit operations.
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