The fastest way to reduce JPEG size

Open your JPEG in any image editor — Windows Photos, Mac Preview, or free tools like GIMP or Photopea — and export it again at a lower quality setting. Most editors let you choose a quality slider from 1 to 100 when you save. Dropping from 100 to 75 or 80 usually cuts the file size in half while the image still looks sharp on screen. This takes 30 seconds and works on any device.

If you need the file smaller still, resize the image dimensions themselves. A photo that is 4000 pixels wide takes up more space than the same photo at 2000 pixels wide, even at the same quality setting. For web use, images rarely need to be larger than 2000 pixels in their longest direction.

The trade-off is straightforward: lower quality setting = smaller file, but slightly softer image. Smaller dimensions = smaller file, but you lose detail if you ever print it. For email, messaging, or posting online, quality 75 and a width of 2000 pixels solves most problems.

Key Takeaways

  • Lowering the quality setting when you export a JPEG (usually to 75–85) cuts file size by half or more without visible loss on screen.
  • Resizing the image width to 2000 pixels or less for web use reduces file size further, but you cannot enlarge it later without blurriness.
  • Windows Photos, Mac Preview, and free online tools like Photopea all have quality sliders built in — you do not need special software.
  • JPEG compression is "lossy," meaning it discards data to shrink the file; PNG and other formats work differently and may not shrink as much.

Understanding JPEG compression and why quality matters

JPEG is a lossy format, which means it throws away some image data to make the file smaller. When you save a JPEG at quality 100, it keeps almost all the data. At quality 75, it discards data that human eyes usually cannot see — fine texture in backgrounds, subtle color gradations, tiny details. At quality 50, the loss becomes visible as blotchy artifacts and soft edges.

The quality number is not standardized across all software, so quality 75 in Photoshop may look slightly different from quality 75 in Preview. The best approach is to export at your target quality, open the result, and look at it at 100% zoom. If it looks acceptable, you are done. If it looks worse than you need, raise the quality by 5 points and try again.

File size also depends on image content. A photo of a solid blue wall compresses much smaller than a photo of a busy forest, even at the same quality setting, because there is less variation for the compression to encode.

How to reduce JPEG size in Windows Photos

Right-click the JPEG file and select "Open with" → "Photos." Once the image opens, click the three-dot menu in the top right and select "Edit." At the top, click "Crop & rotate" (or skip this if you do not need to crop). Click the back arrow to return to the main view.

Click the three-dot menu again and select "Save as." Choose a new filename and location. At the bottom of the dialog, you will see "Quality" with a slider. Drag it to 75 or 80, then click "Save." Windows will create a new, smaller file and leave the original untouched.

If you need to resize the image dimensions as well, click "Crop & rotate" before saving. You can drag the corners to make the image smaller, or click the aspect ratio button to lock proportions while you resize.

How to reduce JPEG size on Mac with Preview

Open the JPEG in Preview (it is the default image viewer). Click "Tools" in the menu bar, then "Adjust Size." You will see the current width and height in pixels. To shrink the file, lower the width to 2000 or less. Make sure the chain-link icon between width and height is connected so the proportions stay correct. Click "OK."

Now click "File" → "Export." A dialog will open. At the bottom, you will see "Quartz Filter" set to "None." Leave it as is. Below that is a quality slider labeled "Quality." Drag it to 75 or 80. Choose a new filename if you want to keep the original, then click "Save."

Preview does not always show the quality slider in the export dialog on older Mac versions. If you do not see it, use the free online tool Photopea instead, which works the same way on any device.

Using free online tools when you do not have software

Go to Photopea.com in any web browser. Click "File" → "Open" and select your JPEG from your computer. Once it loads, click "File" → "Export As." Choose JPEG format. A dialog will appear with a "Quality" slider. Set it to 75 or 80 and click "Export."

Photopea works on phones, tablets, and computers. Your image stays on your device — it does not upload to Photopea's servers. If you need to resize dimensions as well, click "Image" → "Image Size" before exporting, lower the width to 2000 pixels, and then export.

Other free online options include TinyJPG.com and Compressor.io, which are designed specifically for shrinking images. You upload the file, they compress it, and you read the result. These tools are simpler but give you less control over the quality setting.

When to resize dimensions instead of just lowering quality

Lowering quality alone is the right choice if you might need the full resolution later — for example, if you are archiving photos or sending them to someone who might print them. The file gets smaller, but the dimensions stay the same, so you can always enlarge it back to full size if needed.

Resizing dimensions is the right choice if the image is too large for its purpose. A photo that is 4000 pixels wide is overkill for email, social media, or a website. Shrinking it to 2000 pixels wide cuts the file size dramatically and is the standard practice for web images. Once you resize, you cannot enlarge it later without blurriness, so only do this if you are sure you will not need the larger version.

For most people, the best approach is to do both: lower the quality to 75–80 and resize the width to 2000 pixels. This gives you a file that is typically 80–90% smaller than the original while still looking good on any screen.

Why PNG and other formats might not shrink as much

PNG is a lossless format, meaning it keeps all the image data and does not discard anything to shrink the file. A PNG file is usually larger than a JPEG of the same image, even though it looks identical. PNG is better for images with text, logos, or areas of solid color, because JPEG compression can make those look blotchy. For photographs, JPEG is almost always smaller.

If you have a PNG and want to shrink it, converting it to JPEG will usually make it much smaller. Open the PNG in any image editor, export it as JPEG at quality 75, and the file size will drop significantly. The trade-off is that you lose the lossless quality — if you need to edit the image later, work from the PNG and convert to JPEG only when you are done.

WebP is a newer format that compresses better than both JPEG and PNG, but not all devices and browsers support it yet. For now, JPEG remains the standard for photographs and the easiest format to shrink.

Frequently Asked Questions

What quality setting should I use?

Start with 75 or 80. Open the result at full size and look at it. If it looks acceptable, you are done. If it looks worse than you need, raise it to 85. For web and email, 75 is usually fine. For images you might print, use 85 or higher.

Can I shrink a JPEG without losing any quality?

No. JPEG is lossy, so any compression discards some data. You can lower the quality only slightly (to 95 or 98) to keep the loss invisible, but the file will not shrink much. If you need zero quality loss, use PNG instead, but the file will be larger.

What is the smallest file size I can get?

It depends on the image content and dimensions. A small, straightforward photo might shrink to 50 KB at quality 75 and 2000 pixels wide. A large, detailed photo might be 500 KB at the same settings. There is no universal minimum — test your specific image and adjust the quality and size until you reach your target.

Will shrinking a JPEG make it blurry?

Lowering quality can make it look slightly softer, but usually not noticeably blurry at quality 75 or higher. Resizing the dimensions (making it smaller in pixels) can make it look blurry if you try to enlarge it later. For the original size, resizing does not cause blurriness.

Do I need to buy software to shrink JPEGs?

No. Windows Photos and Mac Preview are free and built in. Photopea, TinyJPG, and Compressor.io are free online tools that work on any device. You only need paid software like Photoshop if you are doing advanced editing.