Thumbnail Generator
Resize any image to an exact thumbnail size for YouTube, Instagram, Facebook, X, LinkedIn, Pinterest or a custom width and height. Upload images, pick a size, choose crop or padding, click Generate All and download each thumbnail or a ZIP. It all runs in your browser, so your images are never uploaded.
Upload Images
or drop images here • 0 images added
Preset Sizes
YouTube
Social Media
Custom Size
Settings
Keep this part when cropping
Higher quality = larger file size
Thumbnails (0)
No images uploaded
Add as many images as you like — JPG, PNG, WebP, GIF, BMP, SVG and more
Thumbnail generator: resize images to exact sizes, free and private
To make a thumbnail for free, click Upload Images (or drop your pictures on the Upload Images box), choose a size under Preset Sizes or type a Custom Size, pick Crop to fit or Contain, and click Generate All. Then click Download JPG on each result, or Download All (ZIP). For a YouTube thumbnail, the YouTube 4K preset gives 3840 × 2160 pixels, the 16:9 size YouTube recommends.
A thumbnail generator like this one does not design anything; it resizes and crops existing images to an exact width and height. It runs in your browser, so nothing is uploaded (you can check the Network tab in DevTools). The default output is JPG at 90% quality, and files are named like photo-1280x720.jpg.
Want a title or logo on the picture? Add it first with the Add Text to Image tool or the image overlay tool, then generate the exact size here. For a single free-form resize, the image resizer is quicker.
Table of Use: which preset for which job
These are the preset sizes built into the tool. Platforms revise their layouts now and then, so treat them as starting points; the YouTube figure is sourced in the FAQs.
| Use | Preset | Size (px) | Shape |
|---|---|---|---|
| YouTube video, recommended size | YouTube 4K | 3840 × 2160 | 16:9 |
| YouTube video, smaller file | YouTube Standard or YouTube HD | 1280 × 720 or 1920 × 1080 | 16:9 |
| Instagram feed post | Instagram Square or Instagram Portrait | 1080 × 1080 or 1080 × 1350 | 1:1 or 4:5 |
| Link preview on Facebook or LinkedIn | Facebook Link / Post, LinkedIn Link | 1200 × 630, 1200 × 627 | about 1.91:1 |
| Picture or link card on X | X (Twitter) Post, X (Twitter) Link Card | 1200 × 675, 1200 × 600 | 16:9, 2:1 |
| Pinterest pin | Pinterest Pin | 1000 × 1500 | 2:3 |
| Blog image, product tile, anything else | Custom Size | Any whole number from 1 to 10,000 per side (starts at 800 × 600) | Your choice |
Crop to fit, Contain or Stretch
| Fit | What happens | Choose it for |
|---|---|---|
| Crop to fit | Fills the frame; edges outside it are cut off | Photos and video frames |
| Contain (add padding) | Shows the whole image; spare space gets the background colour | Products, diagrams, logos, group shots |
| Stretch to fill | Fills the frame by distorting the picture | Rarely; flat backgrounds and patterns |
Features
- Ten presets and a custom size. Three YouTube sizes, seven social sizes, or any whole-number width and height up to 10,000 px.
- Crop position. A nine-point grid labelled "Keep this part when cropping" lets you keep the top of a portrait or the centre of a landscape. With Contain, the same grid places the image inside the padding.
- JPG, PNG or WebP. JPG and WebP have a Quality slider from 50% to 100%. Transparent areas in a JPG, and the padding in Contain mode, use the Background colour you pick (white by default). If a browser cannot write WebP, it saves a PNG instead and the card button reads Download PNG.
- Batch with Generate All. Every image gets identical settings. If you change a setting later, cards are flagged as out of date and only those are redone.
- Size check. Each card shows the original size and the new file name and size. On YouTube presets, a file over 2 MB gets a warning, because the mobile app limit is 2 MB.
- One ZIP. Download All (ZIP) saves thumbnails.zip, and files that would share a name are numbered instead of overwritten.
How the fit maths works
Crop to fit scales the image by the larger of target width / image width and target height / image height. Contain uses the smaller of the two. Take a 4000 × 3000 photo and a 1280 × 720 target: Crop to fit scales by 0.32 to 1280 × 960 and trims 240 px of height (120 px top and bottom with Center). Contain scales by 0.24 to 960 × 720 and adds 160 px of background on each side.
Because the scale is not capped at 1, an image smaller than the target is enlarged. Start from the biggest original you have. Afterwards, shrink the file with the image compressor, or convert it with the PNG to WebP converter or PNG to JPG converter.
How to generate thumbnails, step by step
- Click Upload Images, or drop JPG, PNG, WebP, GIF, BMP or SVG files on the Upload Images box. Files that are not images are skipped with a notice.
- Under Preset Sizes pick a YouTube or social size. For anything else, type Width (px) and Height (px) under Custom Size and click Use Custom Size.
- Under Settings, choose Fit: Crop to fit, Contain (add padding) or Stretch to fill, then click a square in the position grid.
- Choose the Format (JPG, PNG or WebP) and, for JPG and WebP, the Quality. Set the Background colour if it is shown.
- Click Generate All and compare each Thumbnail with its Original.
- Click the Download button on a card (for example Download JPG), or Download All (ZIP).
To protect a logo or name on the result, stamp it with the add watermark tool; to trim an image by hand first, use the image cropper.
Who can use it
- YouTubers and video editors who export a frame and need it at exactly 16:9.
- Social media managers preparing one image for several networks, perhaps combined in a collage first.
- Bloggers and shop owners who need a folder of images at one uniform size, plus a border from the image border adder if they like.
- Designers and developers who need preview images or cut-outs from the background remover placed on a flat colour.
FAQs
What size should a YouTube thumbnail be?
As of October 2026, YouTube Help ("Add custom thumbnails on YouTube") asks for a 16:9 thumbnail at least 640 pixels wide, recommends 3840 × 2160 pixels, and accepts JPG or PNG. The file limit is 50 MB on a computer but 2 MB in the YouTube mobile app. Use the YouTube 4K preset for the recommended size, or YouTube Standard (1280 × 720) or YouTube HD (1920 × 1080) for smaller files.
Is it safe to make thumbnails online, or are my images uploaded?
This thumbnail generator does not upload your images. Each one is decoded, resized and encoded by your own browser on an HTML canvas, so nothing is sent to ZipConvert or anyone else, and you can confirm it in the Network tab of DevTools. The one extra request is the first click on Download All (ZIP), which loads the ZIP-building code from ZipConvert. Images are discarded when you close the tab.
Should I use Crop to fit or Contain?
Crop to fit fills the whole thumbnail and trims whatever sticks out, so there are no empty bars; the position grid picks which part to keep. Contain shows the entire image and fills the leftover space with your background colour, which suits products, diagrams and group photos. Stretch to fill distorts the picture to the new proportions and is rarely what you want.
Which sizes do the Instagram, Facebook, X and LinkedIn presets use?
Instagram Square is 1080 × 1080 and Instagram Portrait 1080 × 1350. Facebook Link / Post is 1200 × 630, X (Twitter) Post 1200 × 675 and X (Twitter) Link Card 1200 × 600, LinkedIn Link 1200 × 627 and Pinterest Pin 1000 × 1500. Platforms change their layouts, so check their guidelines before an important campaign; for any other size use Custom Size.
What file format and quality should I use for thumbnails?
JPG gives small photo files that every platform accepts, and 85-95% quality is a sensible balance; the slider runs from 50% to 100%, with 90% the default. PNG is lossless but larger and has no quality slider. WebP is usually smaller than JPG, but YouTube asks for JPG or PNG. Transparent areas in a JPG are filled with the background colour you choose.
Can this tool add text or a logo to my thumbnail?
No. It resizes, crops or pads existing images to an exact size and does not draw on them. To put a title, logo or watermark on the picture, add it first with the Add Text to Image, Image Overlay Tool or Add Watermark tool, then bring the finished image here to generate the exact thumbnail size.
Why does my thumbnail look blurry?
The usual cause is a source image smaller than the target size. Both Crop to fit and Contain enlarge a small image until it fills or fits the frame, which softens it. Check the "Original" width and height shown on each card. A 640 × 360 photo enlarged to 1920 × 1080 will look soft, so start from a larger original or choose a smaller preset.
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