How to reduce image file size — shrink many photos without visible loss

Email attachment limits, upload caps on forums and marketplaces. A phone photo is 3–8 MB, so a few of them are enough to hit the limit. There are two ways to make them smaller, and which one you start with makes a big difference.

Two things decide file size

• Dimensions (pixels) — width × height. Phone photos are typically around 4000×3000.
• Quality (compression) — how carefully those pixels are stored.

Reduce the dimensions first. Halving width and height leaves a quarter of the pixels, and the file shrinks roughly as much. On screen it looks the same, because a 4000 px photo was usually being shown 1000 px wide anyway.

Lower the quality only after that. Push quality too far and the damage shows, and it never saves as much as resizing.

Shrinking a batch

• Drop all the photos into Bulk Image Resizer. There is no limit on the number.
• Under Size, choose Long edge and enter a number: about 1600 px for a blog or listing, 1280 px for email. Landscape and portrait photos in the same batch shrink the same way, by their longer side.
• For Format, choose WebP if the destination accepts it, otherwise JPEG.
• Leave quality at the default 0.80.
• Press Convert. Each file shows its new size. Use Download as zip to get them all.

Images already smaller than the target are not enlarged — upscaling makes them blurrier and bigger.

How small do they get?

A typical phone photo (4000×3000, around 4 MB) resized to a 1600 px long edge as JPEG at 0.80 usually ends up at a few hundred KB. It varies: wide skies compress well, busy textures like foliage less so.

The tool does not target an exact size such as "under 100 KB". If you have a hard limit, lower the long edge a step and press Convert again — you do not need to add the files again; new settings apply to the same files. For ID photos with a size rule, the ID photo size fitter has a file-size cap that does target KB.

When not to shrink

• Photos you will print — screen-sized files print blurry. Keep the originals.
• Your archive — the tool never changes the original and always saves new files, but do not overwrite originals with the smaller copies.

How low quality can go is covered in what quality setting to use.

Open the Bulk Image Resizer