Les miniatures YouTube doivent faire exactement 1280×720 pixels au ratio 16:9. Importez autre chose et YouTube rejette le fichier ou le compresse jusqu'au flou. Ce redimensionneur de miniatures YouTube gratuit recadre et met à l'échelle n'importe quelle image aux bonnes dimensions instantanément, sans inscription, sans filigrane, sans perte de qualité. Fonctionne pour les vidéos standard, les miniatures verticales des Shorts et les bannières de chaîne.
Official YouTube thumbnail specs in 2026
YouTube's documented thumbnail requirements: 1280×720 pixels minimum (720p), 16:9 aspect ratio, under 2MB file size, JPG/GIF/PNG format. The 16:9 ratio is mandatory, non-16:9 images get auto-cropped with black bars or stretched into distortion.
Upload at 1920×1080 (still 16:9) if you have the source resolution, YouTube downsamples to display sizes, and a higher-res master future-proofs as YouTube rolls out 4K thumbs to TV screens. The resizer above outputs at 1280×720 by default and offers 1920×1080 if your source supports it.
YouTube Shorts thumbnails: different rules
Shorts thumbnails follow a 9:16 vertical ratio instead of 16:9. Recommended size: 1080×1920 pixels. Same 2MB cap, same JPG/PNG/GIF format support.
Shorts thumbnails matter less than video thumbnails in the discovery flow, Shorts mostly auto-play from the feed without needing a thumbnail click. But your Shorts thumbnail still shows up on your channel page, in playlists, and in mobile search results. So treat it as a 'looks good when scrolling' image rather than a 'must hook the click' image. The resizer has a 9:16 preset for Shorts.
Why your thumbnail looks blurry on YouTube
Three common reasons. (1) Source image is too small, upscaling a 640×360 thumbnail to 1280×720 introduces visible blur. Always start from a source that's at least 1280×720. (2) JPEG compression artifacts, saving a JPG at low quality (under 80%) for upload creates blocky artifacts that YouTube's compression makes worse. Save at 90%+ quality. (3) Text too small, YouTube's mobile feed shows thumbnails at roughly 320×180 pixels. Text under 60pt at source size becomes illegible at display size.
The resizer preserves source quality and shows a mobile-preview overlay so you can spot text-too-small issues before upload.
Thumbnail design rules that boost click-through
Click-through rate (CTR) on thumbnails averages 4-6% on YouTube. Top performers hit 10%+. The patterns that drive higher CTR: high-contrast colors (especially yellow/red against dark backgrounds), large readable text (3-5 words max), a single dominant face with expressive emotion, and a clear value-prop visible at mobile-feed size.
Avoid: cluttered backgrounds, four+ visual elements competing for attention, low-contrast text (white-on-light-background, dark-on-dark), and overly literal images of the topic (a thumbnail of 'a coding tutorial' showing code is weaker than 'a confused person looking at code'). The resizer doesn't change your design, but the mobile preview helps you spot the worst offenders.