主要フォーマット

YouTubeサムネイルサイズ：1280×720でCTR

A thumbnail isn’t a poster—it’s a stamp in a sea of stamps. Design mobile-first: big face, little text, brutal contrast.

Design for stamp size

1280×720 is the master, but users see it tiny. Three elements max. Long copy belongs in the video title, not the thumb.

Expressive faces beat pretty landscapes. Contrast subject vs background.

Thin or script text.

Same face/expression on every thumb (fatigue).

Crops that clip eyes or key products.

YouTube → Thumbnail → frame with fill → download. No third-party upload of your master.

Official YouTube thumbnail size?

1280×720, 16:9, usually JPG under 2 MB.

Can I use 1920×1080?

YouTube rescales, but composing at 1280×720 avoids sharpness/compression surprises.