The fastest way to shrink a JPEG

Open your JPEG in Windows Photos (built into Windows) or Preview (built into Mac), then export or save it at a lower quality setting. This takes 30 seconds and cuts file size by half or more without any visible difference to the human eye. You do not need to read anything or learn new software.

The reason this works: JPEG is a lossy format, meaning it already throws away some image data to stay small. When you re-save it, you can throw away more. A photo that looks perfect at 85% quality might be 40% smaller than the original 95% quality version, but you will not see the difference on a screen or in a print.

If you have many JPEGs to shrink at once, batch processing tools like IrfanView (Windows, free) or ImageMagick (Mac and Windows, free command-line tool) will do dozens in minutes. But for one or two files, the built-in method is faster than learning a new program.

Key Takeaways

  • Lowering the quality setting to 80–85% when you re-save a JPEG shrinks it dramatically while keeping it visually identical to the original.
  • Windows Photos and Mac Preview both let you adjust quality during export without installing anything new.
  • Resizing the image dimensions (making it narrower and shorter) shrinks file size more than quality alone, but changes what you see.
  • Batch processing tools like IrfanView or ImageMagick save time if you have more than five or six files to compress.
  • JPEG works best for photographs; PNG works better for graphics with solid colors or text, and may actually be larger for photos.

Lowering quality in Windows Photos

Right-click the JPEG file and open it with Photos. Click the three dots in the top right, then select "Edit a copy" or "Save as". Choose a location and filename, then look for a quality or compression slider before you click Save. Move the slider left to reduce quality — start at 80 and see the result. Windows will show you the new file size before you confirm.

If you do not see a quality slider, you are using an older version of Photos. Instead, use the free online tool Squoosh (squoosh.app), which runs in your web browser. Upload the JPEG, drag the quality slider to 80, and read the result. No account needed.

Lowering quality on a Mac

Open the JPEG in Preview (the default image viewer). Click File, then Export. A dialog box appears. Under Format, make sure JPEG is selected. Below that, you will see a Quality slider. Drag it to the left — 80 is a good starting point. The dialog shows the new file size. Click Save.

If the Quality slider does not appear, click the Options button to reveal it. Preview sometimes hides it until you ask for it.

Resizing the image to make it smaller

If lowering quality alone is not enough, you can also make the image narrower and shorter. A photo that is 4000 pixels wide but only needs to be 2000 pixels wide for your use will be roughly one quarter the file size. This is the right move if you are shrinking photos for email or a website where they will display at a smaller size anyway.

In Windows Photos, open the image, click Edit, then Crop and rotate. You can resize from there. On a Mac, open Preview, click Tools, then Adjust Size. Enter a new width or height — the other dimension shrinks proportionally. Then export at quality 80 as described above.

The trade-off: a resized image looks blurry or pixelated if you try to print it large or zoom in far. Only resize if the smaller dimensions match how you actually plan to use the photo.

When to use other formats instead

JPEG is built for photographs because it handles gradual color changes well. But if your image is a screenshot, a graphic with solid colors, or text on a background, PNG will often be smaller and will never get blurry. Try saving as PNG and compare file sizes — if PNG is smaller, use that instead.

WebP is a newer format that shrinks photos even more than JPEG, sometimes by 25% at the same quality. Windows 11 and recent versions of Mac can open WebP natively. If your photos are going on a website and you control the code, WebP is worth learning. For email or sharing with others, stick with JPEG because not everyone can open WebP yet.

Batch processing multiple JPEGs at once

If you have 10 or 20 JPEGs to compress, doing them one at a time wastes time. IrfanView (Windows, free) and XnConvert (Windows and Mac, free) both let you select a folder of images and compress them all with one setting.

read IrfanView, open it, go to File > Batch Conversion, select your folder, choose JPEG as the output format, set quality to 80, and click Start. It processes all images in seconds. On Mac, XnConvert works the same way. Both tools also resize in batches if you need that too.

If you are comfortable with the command line, ImageMagick (free, all platforms) is faster and more powerful. The command mogrify -quality 80 *.jpg compresses every JPEG in a folder to quality 80 in place. Learning this takes an hour but saves time if you compress photos regularly.

Checking your results

After you compress a JPEG, open both the original and the new version side by side on your screen at 100% zoom. Look at details like faces, text, and edges. If you see no difference, you compressed enough. If the new version looks blurry or has visible blocks of color, raise the quality setting by 5 and try again.

File size matters less than usability. A photo that looks bad at 200 KB is worse than one that looks perfect at 500 KB. Start at quality 80, check the result, and adjust from there. Most people find 75–85 is the sweet spot for photos.

Frequently Asked Questions

Will compressing a JPEG ruin it?

No. JPEG already compresses when you save it the first time. Lowering quality to 80 from 95 shrinks the file but leaves it visually identical. You only see damage if you go below 60 or compress the same file many times in a row. Compress once, then keep the result — do not compress a compressed file.

Can I make a JPEG smaller without changing quality?

Not significantly. JPEG quality and file size are linked — lower quality means smaller file. You can strip metadata (camera settings, location data) to save a few kilobytes, but that is usually less than 5% of the file. Resizing the dimensions is the only other way to shrink it without touching quality.

What is the smallest file size I can make a JPEG?

That depends on the image. A straightforward photo with few colors might compress to 10% of its original size. A detailed photo with lots of texture might only shrink to 40%. Start at quality 80 and lower it in steps of 5 until the image looks bad, then go back up by 5. That is your minimum.

Should I compress before or after editing?

Compress after you are done editing. Every time you open, edit, and re-save a JPEG, you lose a little quality. Make all your changes in an editor, export to JPEG once at quality 80, and stop. If you need to edit again later, edit the original file or a PNG version, not the compressed JPEG.

Why is my PNG file bigger than my JPEG?

PNG uses lossless compression, which works well for graphics but poorly for photographs. A photo in PNG is often two or three times larger than the same photo in JPEG. Use PNG only for screenshots, graphics, and images with text. For photos, JPEG or WebP will always be smaller.