- Network address
—- Broadcast address
—- Subnet mask
—- Wildcard mask
—- First usable host
—- Last usable host
—- Usable hosts
- —
- Total addresses
- —
- Class / type
- —
Enter something like
192.168.1.10/24 (prefix 0–32).🔒 All maths runs in your browser.
Using an AI agent or a script? Call this tool as an API
AI agents and scripts can call this tool directly, to check their work or look something up, and get JSON back with the same answer this page gives. No key needed.
GET https://digitalgreenhouse.com.au/api/tools/subnet-calculator?cidr=192.168.10.37%2F26cidr— string, required. IPv4 address with prefix length.
The API answers from our server, and our code doesn’t store what you send. Fair-use limits apply. API guide · all endpoints (JSON) · OpenAPI
What a subnet calculator tells you
A CIDR block like 192.168.1.0/24 describes a range of IP addresses. The /24 means the first 24 bits are the network, leaving 8 bits for hosts — 256 addresses, of which 254 are usable (the first is the network address and the last is the broadcast). This tool does that arithmetic for any prefix from /0 to /32, so you can plan a network, configure a firewall rule, or just sanity-check a range.
Why are there two fewer usable hosts?
The first address in a block is reserved as the network identifier and the last as the broadcast address, so a /24 gives 256 total but 254 usable. (/31 and /32 are special cases used for point-to-point links and single hosts.)
Is this IPv4 only?
Yes, for now. IPv6 subnetting works differently (and the numbers get astronomically large). Setting up addressing and firewalls properly is part of the IT work we do for clients.