Thumbnail Creator — Frequently Asked Questions
Everything you need to know about using Thumbnail Creator.
Is my image uploaded?
No. All thumbnails are generated entirely in your browser using Canvas. Your image never leaves your device.
Can I add custom thumbnail sizes?
Yes. Beyond the preset packs, you can add any custom size (e.g., 256×144 for a custom video thumb).
Does it crop or just resize?
Both options are supported per generation. Crop mode produces exact pixel dimensions (best for app icons). Resize mode preserves aspect ratio (best for video thumbs and hero images).
What’s the maximum source image size?
No hard limit, but very large images (50+ megapixel RAW conversions) may slow processing. JPGs up to 30MB convert smoothly.
Why does my thumbnail look pixelated?
If your source image is smaller than the requested thumbnail, the tool can only upscale — results will look soft. For best quality, always start with a source larger than your biggest target size.
Try Thumbnail Creator now
Generate thumbnails in multiple sizes. Free, no signup, 100% private.
Open Thumbnail Creator