How to reduce photo file size: quality, dimensions and format
Phone photos are often several megabytes each, which gets in the way of email attachments, blog uploads and online application forms. There are three ways to make a photo smaller. Once you know what drives file size, you can hit your target while losing as little quality as possible.
Three things that decide file size
1. Compression quality
JPG and WEBP let you choose a quality value when saving. Lowering it a little makes almost no visible difference but cuts the size a lot. Around 70 to 80 percent is usually hard to tell apart from the original on screen.
2. Pixel dimensions
Halving the width and height leaves a quarter of the pixels. Phone photos are often more than 4000 pixels wide, while 1500 to 2000 pixels on the long side is plenty for blogs and messaging in most cases.
3. File format
Photos saved as PNG are very large. If you do not need transparency, converting to JPG or WEBP alone can shrink the file dramatically.
Which method fits your situation
| Situation | Recommendation |
|---|---|
| Uploading many photos to a blog or store | Image Compressor at about 75 percent |
| A limit such as "under 100KB" | Compress to 100KB |
| Making every photo the same size | Batch Resize |
| A huge PNG screenshot | Image Compressor with JPG or WEBP output |
Shrinking many photos at once
- Add all your photos to the Image Compressor. HEIC files work too.
- Leave quality around 75 percent and check the resulting sizes.
- If you need smaller files, turn on the longest side limit and set it to about 2000 pixels.
- Download everything as one ZIP.
Getting reliably under a size limit
When a form says "photo under 100KB", trying quality values one by one is tedious. Enter a target in Compress to 100KB and it lowers quality first, then reduces dimensions if needed, until the file fits.
If the form also sets pixel dimensions, such as 300 pixels wide, resize first and compress second. A smaller image needs less quality loss to fit.
Things to keep in mind
- Re-saving an already compressed photo many times slowly lowers quality. Keep your originals.
- Do not shrink photos you plan to print. Printing needs a lot of pixels.
- Re-saving often drops photo metadata (EXIF) such as GPS location, which is a plus for photos you share publicly.