Bulk resize images for the web

Six ways to say how big you want them. Most web work only needs the first one.

• Longest side caps the biggest edge and lets the other follow. This is the one to use on a mixed folder, because a 1,600px cap works on portrait and landscape shots alike without cropping either.
• Width or Height fixes one edge. Use width when every image drops into the same column.
• Exact size gives a set width and height. When the shape does not match you can pad the gap with a colour, crop to fill, or stretch. Crop is almost always what you want for a social or Open Graph card, and stretch is there for the rare case where the artwork can take it.
• Percentage scales everything by the same amount, which keeps the relative sizes in a set of screenshots.
• File size works backwards from a budget in kilobytes. It lowers quality first and only starts reducing dimensions when the lowest useful quality still is not small enough, which is the order a person would do it in.

The presets across the top set all of this in one click for the jobs that come up most: hero, page content, thumbnail, social square, Open Graph card, and an under-200 KB email version.

Rough targets that hold up across most Singapore business sites:

• Full-width hero: 1,920px on the longest side, under 300 KB. Retina looks after itself, because a phone screen is rarely more than 430 CSS pixels wide.
• Page content and blog images: 1,200px, under 150 KB.
• Cards and thumbnails: 400 to 600px, under 60 KB.
• Logos and icons: SVG if you have it. A PNG at twice its display size if you do not.
• Open Graph and social previews: 1,200 x 630, cropped rather than padded.

Images are usually the largest thing on a page, so they decide your Largest Contentful Paint more than anything else does. Google wants LCP under 2.5 seconds, and a 4 MB hero on a 4G connection uses most of that budget before a single word renders. If you want to see what slow images cost in leads rather than milliseconds, the website cost estimator and the SEO ROI calculator put numbers on both sides of it.

Format matters more than the quality slider for the final file size.

• WebP is the safe default in 2026. Every current browser reads it, it is roughly 25 to 35 per cent smaller than JPG at the same visual quality, and it supports transparency.
• AVIF is smaller again, often half the size of JPG, and it is the best choice for large photographs. Encoding is noticeably slower because the work is real compression rather than a quick pass, so it suits a one-off batch rather than a hundred files in a hurry.
• JPG when something old or awkward has to open the file. Email clients, some CRMs, print suppliers.
• PNG only for flat graphics, screenshots of text, or artwork that needs transparency and must stay lossless. A PNG of a photograph is usually several times the size of the same image as WebP.

JPG has no alpha channel, so anything transparent gets flattened onto the background colour you pick. If you are trying to get rid of a background rather than flatten it, the transparent background maker is the tool for that.

Most browser-based resizers hand the job to the canvas, which uses a cheap box filter. Shrink a 4,000px photo to 800px that way and fine detail aliases: brickwork shimmers, text in a screenshot breaks up, hair goes crunchy.

This one resamples with Lanczos in a background worker, then applies a small unsharp pass to put back the softness that any downscale introduces. It is the same approach a desktop editor takes, and on detailed photos the difference is obvious at 100 per cent. You can turn the sharpening off if you are resizing flat graphics, where it is not wanted.

Two other things happen quietly. EXIF rotation is respected, so a photo taken sideways on a phone comes out the right way up instead of on its side. And metadata is dropped on the way through, which removes GPS coordinates from holiday photos and takes a few kilobytes off every file.

Once the images are the right size, the image trimmer cuts any dead margin off the edges, and the rest of the free image tools work the same way, in the browser with nothing uploaded.