Free Subnet Calculator Online
Free Subnet Calculator Online is a free online tool by US AI. Type any IPv4 address with a CIDR prefix — like 192.168.1.10/24 — and instantly see the network address, broadcast address, first and last usable hosts, total usable hosts, subnet mask in dotted and binary notation, and the wildcard mask. Network admins, students and homelab builders use it daily for IP planning. It runs completely in your browser — no signup, no download, works on mobile and desktop.
📖 How to use
- Enter an IPv4 address (e.g. 192.168.1.10) and a CIDR prefix from 1 to 32 (e.g. 24).
- Press Calculate — the full network breakdown appears instantly in a clean table.
- Everything is computed on your device; nothing is uploaded anywhere.
✨ Why use this tool?
US AI's free subnet calculator does real bitwise math in your browser — accurate for every prefix from /1 to /32. It is fast, private and 100% free forever. Pair it with our IP checker and WHOIS lookup for the full networking toolkit. Bookmark this page and share it with anyone studying for a networking exam.
❓ FAQs
What is a subnet mask? A subnet mask splits an IP address into its network and host parts. A /24 mask (255.255.255.0) means the first 24 bits identify the network and the last 8 bits identify hosts — giving 254 usable addresses.
How many usable hosts does a /24 have? A /24 network has 256 total addresses minus the network and broadcast addresses, leaving 254 usable hosts. In general, a /n network has 2^(32−n)−2 usable hosts (for n ≤ 30).