The fastest way to compress a JPEG is to reduce its dimensions or lower its quality setting

A JPEG file shrinks when you either make the image smaller (fewer pixels) or reduce how much detail the file stores. Most people compress JPEGs by lowering the quality slider in their photo editor — this removes some of the fine detail but keeps the image recognizable. The trade-off is visible: lower quality means softer edges and less color precision, but file sizes can drop by half or more.

If you need the image to stay sharp, resize it instead. An image that is 2000 pixels wide takes up roughly four times as much space as one that is 1000 pixels wide, even at the same quality setting. You can also use both methods together: make the image smaller and lower the quality slightly, which often produces a file small enough to email or upload while still looking acceptable on screen.

Key Takeaways

  • Lowering the quality setting in any photo editor (Photoshop, Preview, Paint, or free tools like Pixlr) shrinks file size but makes the image softer and less detailed.
  • Resizing the image to fewer pixels — for example, from 4000×3000 to 2000×1500 — cuts file size dramatically without changing how sharp it looks at that smaller size.
  • Combining both methods (smaller dimensions plus slightly lower quality) usually produces the best balance between file size and appearance.
  • The amount of compression depends on the original image: photos with large areas of solid color compress more than detailed shots with lots of texture.
  • Once you save a JPEG at lower quality, you cannot recover the lost detail by opening it again — always keep your original file.

Compress a JPEG using built-in tools on Windows or Mac

Windows includes Paint, which opens any JPEG and lets you resize and re-save it. Open the file in Paint, go to Image > Resize, enter new dimensions (in pixels or percentage), and click OK. Then go to File > Save As, choose JPEG format, and the save dialog will show a quality slider before you confirm. Moving the slider left reduces quality and file size; moving it right keeps more detail but makes the file larger.

On Mac, Preview does the same job. Open the JPEG in Preview, go to Tools > Adjust Size to change dimensions, then File > Export. In the export dialog, choose JPEG format and drag the Quality slider. Preview shows the new file size as you adjust it, so you can see the trade-off in real time before you save.

Both tools are free and built into your operating system, so there is nothing to download. The downside is that neither shows you a preview of how the image will look at lower quality — you have to save it and open it again to see the result.

Compress a JPEG using free online tools

Websites like TinyJPG, Compressor.io, and Pixlr let you upload a JPEG, adjust quality and size, and download the compressed version without installing anything. Upload your file, move the quality slider or enter new dimensions, and the tool shows you the original size and new size side by side. Most also show a preview of how the compressed image will look.

The advantage is speed and visibility — you see the result before you download. The disadvantage is that your image travels to someone else's server, which matters if the photo contains private information. Most of these sites say they delete files after a few hours, but read their privacy policy if you are uncertain.

TinyJPG and Compressor.io both offer free compression with a limit on file size (usually 5 MB per file for free users). Pixlr is free with no file size limit but requires you to create an account.

Compress a JPEG in Photoshop or other paid editors

Photoshop, Affinity Photo, and similar editors give you the most control. Open the JPEG, go to Image > Image Size to change dimensions, then File > Export As (or Save for Web in older Photoshop versions). The export dialog shows quality settings, file format options, and a live preview of the result. You can see exactly how the image looks at each quality level before you save.

These tools are worth the cost if you compress images regularly or need precise control, but they are overkill for a one-time task. Most people get the same result faster with Paint, Preview, or a free online tool.

Understanding the quality slider and what it does

JPEG quality is usually shown as a number from 0 to 100, or as a slider. A setting of 90 or higher keeps almost all the detail and produces a file that looks nearly identical to the original — but the file size barely shrinks. A setting of 70 to 80 removes some fine detail but is still acceptable for most photos on screen or in email. Below 70, the image starts to look noticeably softer, with visible color banding and loss of texture.

The exact appearance depends on the image itself. A photo of a landscape with lots of detail looks worse at quality 60 than a simple portrait does, because there is more information to lose. A screenshot or graphic with solid colors compresses well even at lower quality settings.

Start at quality 75 and save a test version. Open it and compare it to the original. If it looks acceptable, you are done. If it looks too soft, try 80 or 85. If the file is still too large, lower it to 70 and resize the image as well.

Resize the image to cut file size without losing quality

An image that is 4000 pixels wide takes up roughly 16 times as much space as one that is 1000 pixels wide (because area scales with the square of the dimension). If you are compressing for email or a website, you almost never need the original size. A photo that is 2000 pixels wide displays at full quality on any phone or computer screen and is a fraction of the original file size.

To resize, open the image in your editor and go to Image > Resize (or Image Size in Photoshop). Enter the new width in pixels — for email or social media, 1500 to 2000 pixels is usually enough. The height adjusts automatically if you have the aspect ratio locked. Save the resized version as a new file so you keep the original.

Resizing is lossless in the sense that the image stays sharp at the smaller size — you are not throwing away detail, you are just displaying fewer pixels. This is often a better choice than lowering quality, because the result looks cleaner.

When to use each compression method

If you are emailing a photo to someone, resize it to 1500 to 2000 pixels wide and set quality to 75. This usually produces a file under 500 KB that looks good on any screen. If the file is still too large, lower quality to 70 or resize to 1200 pixels.

If you are uploading to a website or social media, check what size the platform recommends. Instagram, for example, recommends images no wider than 1080 pixels. Resize to that width and use quality 75 to 80. The platform will compress it further anyway, so there is no point in using higher quality.

If you are storing photos on your computer and want to save space, resize to 2000 to 3000 pixels (depending on how you plan to use them) and use quality 80. This keeps them sharp enough to print or edit later while cutting file size significantly.

If you need the image to remain editable in Photoshop or another editor, do not compress it at all — save it as a PSD or TIFF file instead. JPEG compression is permanent and cannot be undone.

Frequently Asked Questions

Can I compress a JPEG multiple times without losing quality?

No. Each time you open a JPEG, edit it, and save it again as a JPEG, the file loses more detail. Always keep your original file and compress a copy of it. If you need to make changes, edit the original and compress the result, rather than compressing, editing, and compressing again.

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

That depends on the image and how small you are willing to make it. A simple photo resized to 500 pixels wide and saved at quality 50 might be 20 to 30 KB. A detailed landscape at the same settings could be 50 to 100 KB. There is no fixed minimum — lower quality and smaller dimensions always produce smaller files, but at some point the image becomes too blurry to use.

Is there a difference between compressing a JPEG and converting it to a different format?

Yes. Compressing a JPEG makes the file smaller while keeping it in JPEG format. Converting to a different format (like PNG or WebP) changes how the file is structured and may produce a smaller or larger file depending on the image. For most photos, JPEG at lower quality is the smallest option. PNG is better for images with solid colors or text.

Will compressing a JPEG make it look bad?

Not if you do it carefully. Resizing to a reasonable size (1500 to 2000 pixels for most uses) and keeping quality at 75 or higher usually produces an image that looks identical to the original on screen. Only very low quality settings (below 60) or extreme resizing produce visible degradation.

Can I batch compress multiple JPEGs at once?

Yes, but it requires a tool that supports batch processing. Photoshop has a batch feature under File > Automate > Batch. Free tools like XnConvert (Windows and Mac) let you load multiple files, set compression and resize settings, and process them all at once. Online tools usually handle one file at a time.