CIDR / Subnet Calculator
🔒 In your browserCompute network, broadcast, mask, and host range.
| cidr | 192.168.1.0/24 |
| netmask | 255.255.255.0 |
| network | 192.168.1.0 |
| broadcast | 192.168.1.255 |
| firstHost | 192.168.1.1 |
| lastHost | 192.168.1.254 |
| totalHosts | 256 |
| usableHosts | 254 |
About the CIDR / Subnet Calculator
CIDR notation like 192.168.1.0/24 compactly describes an IP range, but working out the network address, broadcast, mask and host count in your head is hard. This free CIDR / subnet calculator does the math instantly for any IPv4 block.
It runs entirely in your browser.
What it calculates
- Network and broadcast addresses.
- Subnet mask and wildcard mask.
- First and last usable host, and total number of hosts.
Reading common prefix lengths
- /8 — 16,777,216 addresses (a huge network, e.g. 10.0.0.0/8).
- /16 — 65,536 addresses (a typical large private range).
- /24 — 256 addresses, 254 usable (the classic "class C" LAN).
- /30 — 4 addresses, 2 usable (a point-to-point link).
Frequently asked questions
What is CIDR notation?
Classless Inter-Domain Routing notation writes an IP range as an address plus a prefix length, like 10.0.0.0/8, where the number after the slash is how many bits identify the network.
How many hosts are in a /24?
A /24 has 256 addresses, of which 254 are usable for hosts (the network and broadcast addresses are reserved).
Does it support IPv6?
This calculator focuses on IPv4 subnetting, the most common need for planning networks and firewall rules.
What does the number after the slash mean?
It's the prefix length — how many leading bits identify the network rather than the host. A larger number means more network bits and fewer hosts, so /24 is a smaller subnet than /16.
How do I split a network into smaller subnets?
Increase the prefix length: a /24 splits into two /25s, four /26s, and so on. Each step up halves the host count. The calculator shows the resulting range so you can plan the split.
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🔗 Embed this tool on your website — free
Copy this and paste it into your page's HTML. The tool runs in the visitor's browser, just like here. Change height to fit, or add the optional auto-resize snippet below. Add ?theme=dark to the URL for dark mode.
<iframe src="https://toolhq.dev/embed/cidr-calculator/" title="CIDR / Subnet Calculator — ToolsHub" width="100%" height="520" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" loading="lazy"></iframe>Optional: auto-resize the iframe height
Add this once on the same page so the iframe grows to fit the tool:
<script>
addEventListener("message", function (e) {
if (e.data && e.data.type === "toolshub:resize") {
document.querySelectorAll('iframe[src*="/embed/"]').forEach(function (f) {
if (f.contentWindow === e.source) f.style.height = e.data.height + "px";
});
}
});
</script>