red

#FF0000

CSS color

Red (#FF0000) is pure, maximum-intensity red in the CSS named colour set and web colour standard, defined as the full red channel of the RGB model with zero green or blue. One of the three primary colours of light, it is simultaneously the colour of danger, passion, love, revolution, and vitality across cultures worldwide. In digital design, pure #FF0000 is rarely used directly as its extreme intensity causes halation on screens, but it anchors the entire warm colour spectrum.

カラー値

HEX

#FF0000

RGB

255, 0, 0

HSL

0.0, 100.0%, 50.0%

HSV

0.0, 100.0%, 100.0%

CMYK

0.0%, 100.0%, 100.0%, 0.0%

OKLCH

0.628 0.2577 29.2

プロパティ

暖色 明るい 最も近い: red

色彩心理学

Pure red is the color of adrenaline, passion, and urgency. It raises heart rate and stimulates appetite, which is why fast-food chains and sale banners rely on it worldwide. Culturally, red signifies luck and prosperity in East Asia while representing danger and prohibition in Western road signage.

Design Usage

Medium red is ideal for call-to-action buttons, sale badges, and notification dots where instant attention is needed. It should be used sparingly as an accent rather than a dominant background to avoid visual fatigue. Red pairs effectively with white text for maximum legibility in buttons and banners.

カラーハーモニー

色覚異常シミュレーション

CSS使用法

background-color: #FF0000;
color: #FF0000;
border-color: #FF0000;
最も近いTailwind: Red 600 #DC2626

Tailwindシェード

コントラストチェッカー

白背景のテキスト

4.0:1

AA Fail AAA Fail

黒背景のテキスト

5.25:1

AA Pass AAA Fail

比較する

この色を使用しているブランド

含まれているコレクション

関連記事

よくある質問

What are the RGB, HSL, and CMYK values of #FF0000?

RGB(255, 0, 0) · HSL(0.0, 100.0%, 50.0%) · CMYK(0.0%, 100.0%, 100.0%, 0.0%)

Does #FF0000 meet WCAG contrast on white?

4.0:1 — WCAG AA 不合格, AAA 不合格 for normal text.

What text color is readable on #FF0000?

Use 000000 text on a #FF0000 background; contrast on black is 5.25:1.