CIDR / Subnet Calculator
Calculate network, broadcast, host range and mask for IPv4 CIDR.
Use CIDR / Subnet Calculator to plan subnets and sanity-check CIDR blocks in seconds. It's the everyday, free companion for firewall rules, ACLs and VPNs — full IPv4 coverage, computed privately in your browser.
About CIDR / Subnet Calculator
CIDR / Subnet Calculator calculate network, broadcast, host range and mask for IPv4 CIDR for any IPv4 block, instantly. It's the everyday subnetting companion for planning firewall rules, ACLs and VPNs, or simply sanity-checking a CIDR before you ship it. Like every ToolJolt utility it runs 100% in your browser — no sign-up, no upload, and nothing ever sent to a server, so it's safe for proprietary code and confidential data.
How to use CIDR / Subnet Calculator
- 1Enter an IPv4 address and prefix (e.g. 10.0.0.0/24).
- 2The network details are calculated instantly.
- 3Copy the summary into your docs, firewall rules or tickets.
- 4Change the block and the results update live.
Why use CIDR / Subnet Calculator?
- ✓Instant network, broadcast, range and mask
- ✓Handles the full IPv4 address space
- ✓Copy a clean summary in one click
- ✓No server round-trip — everything is local
Frequently asked questions
What can I do with CIDR / Subnet Calculator?+
Plan subnets, firewall rules, ACLs and VPNs, or just sanity-check a CIDR block. It shows the network and broadcast addresses, usable host range, netmask and wildcard mask at a glance.
Does CIDR / Subnet Calculator support large ranges?+
Yes. Calculations run locally and cover the full IPv4 space, so even a /8 is computed instantly without contacting any server.
Is CIDR / Subnet Calculator free?+
Yes. CIDR / Subnet Calculator is completely free with no sign-up, no account, no usage limits and no watermarks. Use it as often as you like.
Does CIDR / Subnet Calculator send my data to a server?+
No. CIDR / Subnet Calculator runs entirely in your browser with JavaScript — your input never leaves your device, which makes it safe for private API payloads, schemas and source code.
Embed CIDR / Subnet Calculator on your website
Want CIDR / Subnet Calculatoron your own site? Paste this snippet into any HTML page — it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
<iframe src="https://tooljolt.com/tools/cidr-calculator" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="CIDR / Subnet Calculator — ToolJolt" loading="lazy"></iframe>