Upload high-contrast master
Upload a landscape source with a clear face, key copy, or strong color contrast — these decide readability at small scales.
YouTube Thumbnail Resize
YouTube custom thumbnails follow the 1280×720px (16:9), under-2MB JPG spec — but the real CTR lever is not size, it is recognizability across scales. The same thumbnail shrinks to about 246×138px in the home feed, 360×202px in search results, and 138×77px in the mobile suggested sidebar; for click-through to lift, faces and key copy have to read within 0.5 seconds at the smallest size. The YouTube algorithm also auto-measures CTR when the same thumbnail repeats to a viewer, so the fastest growth lever for many channels is rapidly producing A/B variants (face vs copy, red vs blue) from the same 1280×720px master. This tool previews readability at the sidebar 138×77px scale while exporting under 2MB at 1280×720px JPG.
How to use
Check sidebar 138×77 readability
Check the sidebar 138×77px preview: if the face or headline word is illegible there, click-through suffers even at full size.
Spin A/B variants and export under 2MB
Spin off two or three variants from the same master for an A/B test, then export under 2MB at 1280×720px JPG.
When to use this tool
Thumbnails decide the first click faster than the video itself. Channels that ship two or three variants per video for an A/B test consistently report higher average CTR than channels that only nail the size spec.
Spinning two or three A/B variants per video to keep the CTR-improvement cycle moving
Stress-testing whether a thumbnail still reads at the sidebar 138×77px scale before uploading
Preventing 2MB upload rejections from 4K Canva or Photoshop PSD exports
YouTube Custom Thumbnail Spec Guide
Recommended sizes as of 2025. Thumbnails appear in search results, suggested videos, and the home feed, making them critical for click-through rates.
| 1280 × 720px |
| Aspect ratio 16:9 |
| File format: JPG, PNG, GIF (under 2MB) |
| Bright colors and high-contrast text stand out even at small sizes. |
| Thumbnails with expressive faces tend to earn higher click-through rates. |
| Keep text to 6–8 words or fewer. |
| Video duration badge overlaps the bottom-right corner. |
| A watch-time badge may appear in the top-left. |
| Large, bold text with 3–5 words is most effective for CTR. |
| Maximum file size: 6MB (for thumbnails) |
| Supported formats: JPG, PNG, GIF, BMP |
| Channel banners: 6MB limit; profiles have no separate limit |
FAQ
Is there a file size limit for YouTube thumbnails?
Yes, YouTube limits custom thumbnails to 2MB. For high-resolution images, adjust JPG quality or use an image compression tool first.
Why does my thumbnail look blurry?
If the source image is smaller than 1280×720px, YouTube scales it up, causing blur. Always start with an image at least 1280×720px.
What is the recommended aspect ratio for YouTube thumbnails?
16:9 (1280×720px) is recommended. This ratio displays without cropping across the YouTube player, search results, and suggested video lists.
Any tips for placing text on thumbnails?
The video duration badge overlaps the bottom-right corner, so place text to the left or center. Bold text with 3–5 words works best for readability on mobile.
What do I need to upload a custom thumbnail?
Your YouTube channel must be verified with a phone number. Once verified, you can upload custom thumbnails per video in YouTube Studio.
Intent-based landing pages
YouTube Banner Resizer
Resize your YouTube channel banner to the 2560×1440px specification.
YouTube Channel Art Resizer
Resize your YouTube channel art to the full 2560×1440px canvas.
YouTube Channel Profile Resizer
Resize your YouTube channel profile picture to 800×800px.
YouTube Cover Image Resizer
Resize your YouTube cover image to the 2560×1440px canvas size.
YouTube Image Resizer
Resize images to the 1280×720px HD format for YouTube content.
YouTube End Screen Resizer
Resize images to the 1920×1080px format for YouTube end screens.