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CSS 単位変換

無料のCSS単位変換ツール。ルートフォントサイズに基づいて、px、rem、em、pt、pc、物理単位間で変換します。レスポンシブデザインとCSSワークフローに。

Runs in your browserUpdated Apr 26, 2026

CSS units converter

rem
1rem
em
1em
pt
12pt
pc
1pc
in
0.1667in
cm
0.4233cm

よくある質問

Is 1rem always 16px?

By default, yes — but if you change the root font-size, all rem values scale. We let you set the root for accurate conversion.

rem vs em?

rem is relative to root font-size; em is relative to the parent's font-size. rem is more predictable for layout.

Why use rem over px?

rem respects user font-size preferences (for accessibility) and scales the whole layout consistently.

Is the converter free?

Yes — fully free, no signup.

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