Generate a Set of Thumbnails
The set of sizes a responsive srcset needs, or a gallery's thumbnail ladder, in one pass. Type the widths you want, drop your images, get a ZIP with every combination named by size. No upload, no per-file clicking.
Drop images here
Multiple files allowed
Naming and what's in the ZIP
Files come out as name-800w.webp in fit mode and name-400sq.webp in
square mode, so a srcset is a copy-paste away and the ordering in a file listing
matches the ordering of sizes. Five inputs × four widths is twenty files in one archive.
Square mode scales to fill and centre-crops, which suits avatars, product tiles and grid layouts. Fit mode preserves the aspect ratio and only sets the width — the height falls out of the original proportions.
Picking widths that earn their place
For srcset, aim at the widths your layout actually renders at across breakpoints,
then double the largest for high-DPI screens. A content column that maxes out at 720 CSS
pixels wants something like 1440, 720, 480, 360 — not a ladder up to 4000 px that nobody
downloads. Each extra width is another file to store, purge and pay for.
Upscaling is not prevented: ask for 2000 px from a 900 px source and you get a soft 2000 px file. Keep every width at or below your original.
WebP is the right default for the web — smaller than both PNG and JPG at equivalent quality, with transparency support, and universally supported by current browsers.
FAQ
Why always a ZIP?
Because the point is a set. Even three inputs and four widths is twelve files, which is far past the point where individual download rows help.
Can I set heights instead of widths?
Not here. Fit mode derives height from the aspect ratio; for an exact height use Resize, or square mode if you want a fixed box.
What quality is used for JPG and WebP?
90%, which is visually clean for thumbnails. To control it, use Compress, or Resize to file size for a byte budget.
Is transparency kept?
With PNG and WebP, yes. JPG flattens onto white.