Get the network address, broadcast address, subnet mask, and usable host range for any CIDR block, in your browser.
Updated
/ 5 - Be the first to rate this tool Thanks for rating!
Verification failed - please try again.
Quick check
Please verify you're not a robot to submit your rating.
Give feedback
Tell us what you think about Calculate a subnet from CIDR notation.
- Network
- Broadcast
- Subnet mask
- First host
- Last host
- Usable hosts
- Runs entirely in your browser — your IP is never sent to a server
- Get the network address, broadcast address, mask, and usable host range
- Free, no account required
How it works
-
1
Paste the string, expression, or value you want to inspect.
-
2
It's parsed instantly and broken down on screen.
-
3
Review the details or matches highlighted for you.
-
4
Copy any part of the result you need.
Why use this tool
Every dev utility, one place
Format, convert, encode, decode, and generate — no more juggling ten tabs.
100% private, always
Every tool runs in your browser — your code and data are never sent anywhere.
Works on any device
Runs on Windows, Mac, Linux, iOS, and Android — nothing to install.
Instant results
No queues, no build step — results update as you type.
Built to handle real data
Full Unicode support and RFC-compliant parsing, edge cases included.
Free, always
Free to use, with no rate limits, sign-up, or trial period.
Frequently asked questions
It indicates how many bits of the IP address are strictly locked for the network routing identifier.
Yes, it subtracts the network and broadcast addresses to show exactly which IPs can be assigned to devices.
Yes, the math supports everything from a massive /1 down to a restrictive /32 single host.
The current engine is optimized purely for legacy IPv4 calculations.
Yes, the inverse wildcard mask is provided alongside the standard subnet mask.
From the blog
Reading a JWT Without Trusting It: Claims, Expiry, and the Signature Trap
Decoding a JWT takes a second. Verifying one is a different job entirely — and confusing the two is how auth bugs ship. Here is how to read a token safely while you debug.
Mastering Base64: What It Is, How It Works, and When Not to Use It
Base64 is everywhere in modern web development, from data URIs to authentication headers. Here is a deep dive into how it works and common pitfalls to avoid.
Demystifying JSON: How to Troubleshoot Common Parsing Errors
JSON is the backbone of web APIs, but syntax mistakes can halt your code. Here is how to identify and fix missing commas, unescaped strings, and trailing characters.
Recently viewed
Related tools
Convert Unix file permissions
Convert between octal (e.g. 755) and symbolic (rwxr-xr-x) file permission notation, in your browser.
Parse a cron expression and see its next run times
Paste a 5-field cron expression to get a plain-English summary and the next 5 run times, in your browser.
Build a curl command online
Build a shell-safe curl command from a method, URL, headers, and body, in your browser.
Parse and view HTTP headers online
Paste raw HTTP request or response headers to see them parsed into a labeled table, in your browser.
Validate JSON against a JSON Schema
Paste a JSON document and a JSON Schema to see every validation error with its instance path. Supports draft 2020-12 and draft-07, entirely in your browser.
Test a regular expression online
Test a JavaScript regular expression against sample text and see every match highlighted live.
Convert colors between HEX, RGB, and HSL
Convert a color between HEX, RGB, and HSL instantly in your browser, with a live preview.
Compare two PDFs for free
See every added and removed line of text between two PDF documents.
Compress an image online for free
Reduce image file size while preserving visual quality, right in your browser.
Compress a PDF file for free
Shrink PDF file size while keeping quality readable, right in your browser.
Convert images in bulk for free
Convert many images between JPG, PNG, and WebP at once, right in your browser.
Convert an image format for free
Convert between JPG, PNG, and WebP, right in your browser.