Refentra

YouTube thumbnail: too large to upload?

Drop your thumbnail here. Refentra checks it against YouTube's thumbnail guidance and makes a fitting copy on your device.

or drag it here

On your device · Free · No account

Local file · Drop or choose

Or load from

Choose the destination

Rule: YouTube · Custom video thumbnails

View the rule

Rule: YouTube

Custom video thumbnails

Maximum file size
2 MB
Minimum width
640 px
Format
JPG or PNG
Recommended width
3,840 px
Recommended height
2,160 px

Source: Add custom thumbnails on YouTube ↗ · checked 26 October 2026

Why YouTube rejects the file

  1. The phone limit is lower. Uploading from a phone allows 2 MB; YouTube Studio on a computer allows much more. A 4K PNG made on a computer often fails on the phone.
  2. Too narrow. Thumbnails for videos need at least 640 px width (Shorts: height).
  3. Wrong format. Use JPG or PNG.

How to make it fit

  1. Drop the thumbnail and read the checks.
  2. Choose "Make it fit". Refentra converts large PNGs to JPG and compresses to the phone limit.
  3. Check text and faces in the result, then set it as the thumbnail.

Pitfalls

  • Thumbnails with large text and flat colours can show artefacts in JPG. Check the edges of the text.
  • YouTube recommends 3,840 px × 2,160 px; shrinking pixels is rarely needed, compression usually is.

Questions

Why does it work on my computer but not my phone?

The phone limit is lower than the desktop limit.

Should I use PNG or JPG?

JPG is much smaller for photo-like thumbnails; PNG only if the result stays under the limit.

Other upload destinations

All platforms in the upload check →