Why do the spaces in calc() matter?

Because CSS parses `+` and `-` inside calc as part of the number when they aren't surrounded by spaces. `calc(100%+2px)` reads as “100%” followed by “+2px”, which is a syntax error, and the whole declaration is dropped. It is the single most common bug in naive CSS minifiers, so this tool tracks parenthesis depth and leaves those spaces alone.

Should I minify by hand, or let a build tool do it?

Let the build tool do it if you have one — minification belongs in the pipeline, not in your source. This page is for the cases where there isn't a pipeline: a stylesheet pasted into a CMS, an email template, or an inline block in a landing page.

Does minifying break anything else?

It removes comments, so a licence header goes with them — check your dependencies' terms if you're minifying third-party CSS. Everything else here is whitespace that CSS treats as insignificant. It does not rename classes, reorder declarations or merge rules, all of which can change behaviour.

CSS Minifier

Shrink a stylesheet by removing everything a browser doesn't need: comments, indentation, the space around braces and colons, and the final semicolon in every block. The one thing it will not do is break `calc()` — the spaces around a `+` inside calc are load-bearing, and `calc(100%+2px)` is invalid CSS that a careless minifier will happily produce. Quoted strings and url() values are left exactly as written.

Your text

Result

Nothing is uploaded — this tool runs inside your browser, so your files never leave your device.

Help us improve

Why use this tool

Removes comments, whitespace and the redundant last semicolon in each block
Keeps the spaces inside calc() that CSS requires
Never touches the inside of a quoted string or a url()
Reports the before and after size, and the percentage saved

How it works

1Paste your CSS.
2Read the saving reported underneath the result.
3Copy the minified stylesheet, or download it.

CSS Minifier — frequently asked questions

Typically 15-30% for hand-written CSS with comments and indentation, and close to nothing for a stylesheet a build tool has already processed. The saving reported under the result is the real figure for your file — most of it comes from indentation and comments rather than anything clever.

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