Subnet calculator and VLSM designer
Plan IPv4 networks fast. Get the network address, broadcast, mask, host range, and a full variable-length subnet plan, all in your browser.
Calculate a subnet or design a VLSM plan
IP address
Prefix length
/24Network
192.168.1.0/24
Network address192.168.1.0
Broadcast192.168.1.255
Usable range192.168.1.1 - 192.168.1.254
Subnet mask255.255.255.0
Wildcard mask0.0.0.255
Usable hosts254
IP classC
ScopePrivate (RFC 1918)
All calculations run entirely in your browser. No addresses are sent to a server.
Why subnetting still matters
Subnetting splits one IP range into smaller, isolated networks so you can separate guest, staff, and IoT traffic, control broadcast domains, and use address space efficiently. This calculator handles both single-subnet maths and variable-length subnet masking (VLSM) for multi-segment designs.
What this tool gives you
- Network and broadcast addresses, subnet mask, wildcard mask, and usable host range for any CIDR prefix.
- A VLSM allocation plan that fits each subnet by required host count, largest first, with no overlap.
- Instant, private results. Every calculation runs locally and nothing is sent to a server.
Related WiFi tools
Planning a venue network?
Subnetting is the foundation. Purple layers guest onboarding, captive portals, and location analytics on top of the network you design here, across Cisco Meraki, HPE Aruba, Ruckus, and Juniper Mist.
Talk to a WiFi expert