What does this tool do?
Subnet Calculator takes an IPv4 address plus a CIDR prefix or dotted subnet mask and instantly computes the network address, broadcast address, usable host range and more. It is ideal for network admins, system engineers and students preparing for exams like the CCNA.
How to use it
- Enter an address, domain or value.
- View the results instantly.
- Copy the details you need.
Every network detail at a glance
Enter an IP such as 192.168.1.100 and a mask like /24 or 255.255.255.0, and the tool lists the network address, broadcast address, first and last usable host, subnet mask, wildcard mask, CIDR notation, plus total and usable host counts. It also flags the address class (A, B or C) and whether it falls in a private RFC 1918 range. Edge cases like /31 and /32 adjust the host count correctly.
CIDR slider and ready examples
When you type the mask as a number, a slider from /1 to /32 appears so you can drag it and watch live how the subnet size changes the host count. One-click example buttons fill in 192.168.1.0/24, 10.0.0.0/8 and 172.16.0.0/16 for quick experimentation. Use the copy button to grab the computed network in CIDR notation for pasting into documentation or configs.
Frequently asked questions
Can I enter a dotted mask instead of CIDR?
Yes. In the mask field you can type a CIDR prefix like 24 or a dotted mask like 255.255.255.0; the tool recognizes both and derives the equivalent prefix automatically.
Why is the usable host count two less than the total?
For /30 and wider networks the network address and broadcast address cannot be assigned to hosts, so both are subtracted. A /31 shows 2 hosts and a /32 shows 1.
What is the wildcard mask?
It is the bitwise inverse of the subnet mask and is mostly used in Cisco access control lists (ACLs). For a /24, for example, the wildcard mask is 0.0.0.255.
Is Subnet Calculator free?
Yes. Subnet Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Subnet Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.