IP Subnet Calculator
Enter an IPv4 address with a CIDR prefix, like 192.168.1.0/24, and this calculator works out the subnet mask, network and broadcast addresses, the number of usable host addresses, and the first and last usable host in that range - handy for planning networks or double-checking a subnet.
Subnet mask: 255.255.255.0
Broadcast address: 192.168.1.255
Usable hosts: 254
First usable host: 192.168.1.1
Last usable host: 192.168.1.254
How it works
CIDR notation (e.g. 192.168.1.0/24) combines an IPv4 address with a prefix length that says how many leading bits belong to the network portion. From the prefix, this calculator derives the subnet mask, then applies it to your address to find the network and broadcast addresses and everything in between.
Tip
A /31 is a special case reserved for point-to-point links (RFC 3021): both addresses in the range are usable and there's no separate network or broadcast address. A /32 identifies a single host, with exactly one usable address.
More tools in this category
Regex Tester
Test regular expressions against sample text with live match highlighting.
Cron Expression Parser
Parse a 5-field cron expression into a plain-language schedule and see its next run times.
Text Encoding Converter
Convert text to UTF-8 hex, binary, code points, Base64, URL encoding and HTML entities at once.
Password Generator
Generate strong, random passwords instantly, right in your browser.
JSON Formatter & Validator
Format, validate, and minify JSON instantly in your browser.
UUID Generator
Generate random, RFC 4122 version 4 UUIDs instantly in your browser.
JWT Decoder
Decode and inspect JSON Web Tokens (JWTs) instantly in your browser.
Diff Checker
Compare two blocks of text and instantly see every line that was added or removed.
Slug Generator
Turn any text into a clean, URL-friendly slug in real time.
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal instantly.
Unix Timestamp Converter
Convert Unix timestamps to dates and dates to Unix timestamps, live.
Hash Generator
Generate SHA-1, SHA-256, and SHA-512 hash digests from any text, right in your browser.
Box Shadow Generator
Design a CSS box-shadow visually with live sliders and a color picker, then copy the generated declaration.
Cron Expression Builder
Build a valid 5-field cron expression from a friendly form — no need to memorize the syntax.
Lorem Ipsum Generator
Generate placeholder Lorem Ipsum text by paragraphs, sentences, or words for mockups and layouts.
Markdown Previewer
Write Markdown on the left and see the rendered HTML update live on the right.
HTTP Status Code Lookup
Look up any HTTP status code and see its standard meaning in plain English.
SQL Formatter
Pretty-print minified or messy SQL into readable, indented statements.
Image to Base64 Converter
Convert an image into a Base64 data URI you can paste straight into HTML, CSS, or JSON — entirely in your browser.
Semver Comparator
Compare two semantic version strings and see which one takes precedence, following the official semver rules.