Resize any image to 1280×720 px for YouTube thumbnails. Free, no upload.
The preset makes a 1280 × 720 image (16:9). YouTube Help, checked on 2026-09-28, recommends 3840 × 2160 for video thumbnails with a minimum width of 640 px, JPG or PNG, a 16:9 ratio, and an upload limit of 2 MB from mobile (50 MB on desktop). 1280 × 720 has the right ratio and is double the minimum width; when your source is at least 3840 px wide, type 3840 × 2160 to match the recommendation. From a 4032 × 3024 photo, 378 px are cut from the top and bottom to reach 16:9.
Drop image files hereProcess many files at onceNo upload · processed on this device
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A 16:9 box is wider than a 4:3 photo, so the preset's fill-and-crop keeps the full width and trims the height: 4032 × 3024 becomes a centred 4032 × 2268 before scaling. A portrait photo keeps only 42 % of its height, which is why designed thumbnails are usually composed at 16:9 from the start.
The preset stays at 1280 × 720, a ninth of the pixels of 3840 × 2160. Typing 3840 × 2160 only helps when the source has that many pixels; resizing a smaller picture up adds no detail. Larger PNGs can pass the 2 MB mobile limit — choose JPG output, or compress with a target, when you upload from a phone.
YouTube also lists 2160 × 3840 (9:16) for Shorts thumbnails and 1:1 for podcast playlists, and notes that vertical videos with a 16:9 custom thumbnail get an auto-generated 4:5 thumbnail on the home, explore and subscription pages.
16:9
Width ÷ height = 1.78; 1280 × 720 and 3840 × 2160 both have it.
Minimum width
640 px for video thumbnails, per YouTube Help.
Verified account
Needed to upload custom thumbnails, per the same page.
Preset versus the recommended size (computed from the code)
The source is an example 12-megapixel photo; the crop follows the resize task's cover calculation.
Preset 1280 x 720 = 921,600 px
Recommended 3840 x 2160 = 8,294,400 px (9 x the preset)
Minimum width 640 px
4032 x 3024 photo -> crop 4032 x 2268 (378 px off top and bottom)
-> 1280 x 720 (x 0.317) or 3840 x 2160 (x 0.952)
3024 x 4032 photo -> crop 3024 x 1701, 42 % of the height kept
Both sizes are reductions for this source, so neither invents detail; for a 1920 × 1080 screenshot, 3840 × 2160 would be a 2× enlargement and gains nothing over keeping 1920 × 1080.
Upload it in YouTube Studio
Sign in to YouTube Studio.
From the left menu, select Content.
Open the video you want to edit.
Below "Thumbnail", click Upload file and choose the resized image.
Click SAVE. YouTube notes that the change can take a while to appear.
Steps as written in YouTube Help (computer) on 2026-09-28; custom thumbnails require a verified account.
Check the result
The result list shows 1280×720 (or 3840×2160), and the file name ends with that size.
For uploads from a phone, check that the file is under 2 MB.
In YouTube Studio, look at the thumbnail preview: text near the edges should still be readable at small sizes.
Troubleshooting
Symptom
Likely cause
How to check
Fix
There is no Upload file option
Custom thumbnails need a verified account
YouTube Studio offers only generated options
Verify the channel, then upload
"File too large" on the phone
Mobile uploads allow 2 MB for video thumbnails
File size in the result list
Choose JPG output, or compress with Target size 2000 (1953 for 2,000,000 bytes)
The thumbnail shows as 4:5 on the home page
Vertical video with a 16:9 custom thumbnail; YouTube shows an auto-generated 4:5 there
The video is vertical
Expected per YouTube Help; your thumbnail still appears in the watch feed and history
A Shorts thumbnail: YouTube asks for 9:16 (2160 × 3840 recommended); the preset gives 1080 × 1920, type 2160 × 3840 if the source allows.
Get suggestions in YouTube Studio
You have no designed thumbnail and are happy with generated options.
What this page does not cover
The preset is 1280 × 720, below YouTube's current 3840 × 2160 recommendation; the larger size is a manual entry.
Nerulio cannot check YouTube's thumbnail policies or your account's verification.
Versions and sources
Sizes, formats, limits and steps are quoted from YouTube Help "Add custom thumbnails", read on 2026-09-28. Crop numbers follow src/task/resize.js and fitQuality() in src/image.js.
Example generated with this tool. ZIP tools show their preview; inspect the downloaded archive for every file.
Resize image
Set width and height, with optional aspect-ratio lock.
How it works
Open the source file
Choose the processing mode and settings
Run, inspect the result and download
Supported formats
PNG / JPG / WebP / AVIF / HEIC → PNG — Input decoding and output encoding depend on browser support. Animated inputs are rejected; select a still frame first.
What this tool does
Tiled high-quality mks2013/Lanczos resampling, numeric dimensions and size helpers.
Implementation and verified quality
advanced · Pica tiled mks2013 / Lanczos. Quality qualification is in progress. Pro/Flagship quality has not been established.
Before you export
Actual device memory, storage and codec support. Tested examples are evidence, not a guarantee for every file.
Frequently asked questions
What determines the supported size?
Actual device memory, storage and codec support. Tested examples are evidence, not a guarantee for every file.
Are my files uploaded?
This tool processes the files you open on your device without uploading them. Images you explicitly attach to community posts are uploaded separately. Optional engines and models are downloaded from third parties; those requests expose connection information such as your IP address.
Will my work be saved automatically?
No. Images and editing state stay in this tab; media output can use local temporary storage. Changing language preserves your work; reloading, closing the tab, or following a link to another page can clear it.
