The fastest way to shrink a JPEG

The simplest method is to open the image in your computer's built-in photo editor, export it at a lower quality setting, and save it with a new name. On Windows, use Photos or Paint. On Mac, use Preview. Both let you choose the quality level when you save — moving the slider from 95% quality down to 75% or 80% usually cuts file size in half without visible difference to the human eye.

If you need to resize the image itself (make it physically smaller in pixels), that shrinks the file further. 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. Most photo editors let you change dimensions before you export.

For a single image, this takes under a minute. For dozens of images, you will want a batch tool that processes multiple files at once — see the section below on bulk reduction.

Key Takeaways

  • Lowering JPEG quality from 95% to 75% typically cuts file size by half with no visible change to most viewers.
  • Resizing the image to smaller pixel dimensions (width and height) reduces file size further, and is necessary if the original is much larger than where it will be displayed.
  • Windows Photos, Mac Preview, and free online tools like TinyPNG or Squoosh let you adjust quality and dimensions without installing software.
  • Batch processing tools work on many images at once, which saves time if you have dozens or hundreds of files to reduce.
  • JPEG is already a compressed format, so the gains from switching to a different format are usually small unless you also change dimensions or quality.

Understanding JPEG compression and quality settings

JPEG is a lossy compression format, meaning it throws away some image data to make the file smaller. The quality setting controls how much data gets discarded. At 95% quality, almost nothing is removed. At 50% quality, the image loses detail and may show visible artifacts (blocky areas or color banding). Most photos look fine at 75% to 85% quality.

The relationship between quality and file size is not linear. Dropping from 95% to 90% might save 10%. Dropping from 90% to 75% might save another 30%. You have to test with your own images to find the sweet spot where the file is small enough but still looks acceptable to you.

Other factors also affect JPEG file size: the image dimensions (a 4000×3000 pixel photo is larger than a 2000×1500 one), the amount of detail in the image (a photo of a busy street compresses less well than a simple landscape), and the color profile embedded in the file. Adjusting quality is the easiest lever to pull first.

Reducing file size on Windows

Open the image in the Photos app (built into Windows 10 and 11). Click the three dots in the top right, then select Edit. At the bottom, you will see a slider or menu for quality — move it lower and click Save a copy. The app will prompt you to choose a location and name for the smaller version.

If you prefer Paint, right-click the image file, select Open with, and choose Paint. Go to File > Save as, pick JPEG as the format, and a dialog will appear asking for quality level before saving.

For resizing, use Photos: select the image, click Edit, then look for a crop or resize option. You can specify new dimensions in pixels or as a percentage of the original size.

Reducing file size on Mac

Open the image in Preview (the default photo viewer). Go to Tools > Adjust Size to change the pixel dimensions. Then go to File > Export, choose JPEG as the format, and a slider will appear for quality. Move it to 75% or 80%, then click Save.

Preview also lets you crop the image before exporting, which removes unwanted edges and reduces file size at the same time. Select Tools > Rectangular Selection, draw a box around the part you want to keep, then go to Image > Crop to Selection.

Using free online tools

If you do not want to install software, TinyPNG (tinypng.com) and Squoosh (squoosh.app) both run in your web browser. Upload a JPEG, adjust the quality slider, and download the smaller version. TinyPNG also handles PNG files. Squoosh shows you a before-and-after preview so you can see exactly what quality level looks acceptable.

These tools work on one image at a time, but they are fast and require no account. Your image is processed on their servers, so if privacy is a concern, use a tool that runs locally on your computer instead (like the built-in editors above).

Processing multiple images at once

For 10 or more images, batch processing saves time. On Windows, ImageMagick (a free command-line tool) can resize and compress dozens of files in seconds, but it requires typing commands. XnConvert (xnconvert.com) is a free graphical tool that does the same thing without the command line — add your images, set quality and dimensions, and click Convert.

On Mac, ImageOptim (imageoptim.com) is free and specializes in batch compression. Drag your images into the window and it compresses them in place, replacing the originals with smaller versions. You can also use Automator (built into Mac) to create a workflow that resizes and compresses images, though this requires some setup.

Online batch tools like Bulk Image Converter exist, but they usually have file limits (often 5 to 10 images per upload) and may be slower than desktop software for large batches.

When to resize dimensions versus lower quality

If your image will be displayed on a website or phone screen, it rarely needs to be larger than 2000 pixels wide. A photo that is 4000 pixels wide takes up four times as much space as a 2000-pixel version, even at the same quality setting. Resizing first, then lowering quality, usually produces the best result.

If you are printing the image, keep the original dimensions and only lower quality if the file is too large. Printed photos need more pixels per inch than screen images, so resizing too much will make them look blurry.

For email or messaging apps, aim for under 5 MB per image. A typical photo at 1920 pixels wide and 75% quality is usually 200 KB to 500 KB, which sends instantly.

Frequently Asked Questions

How much smaller will my JPEG get if I lower the quality?

It depends on the original quality and the image content. Lowering from 95% to 75% typically cuts file size by 40% to 60%. Lowering from 75% to 50% cuts it by another 30% to 50%, but visible quality loss becomes noticeable. Test with your own images to find the right balance.

Will I lose quality every time I open and re-save a JPEG?

Yes. JPEG is lossy, so each save removes a little more data. If you need to edit an image multiple times, keep the original and only save the final version as JPEG. Work in a lossless format like PNG or TIFF during editing, then export to JPEG when done.

Should I convert my JPEG to PNG or WebP to make it smaller?

Usually no. PNG is lossless and produces larger files than JPEG for photographs. WebP can be smaller than JPEG at the same quality, but not all devices and programs support it yet. Lowering JPEG quality is simpler and works everywhere.

Can I reduce file size without changing the image at all?

Slightly. Some JPEG files contain extra metadata (camera settings, location data, color profiles) that can be stripped out. Tools like ExifTool remove this data, saving a few kilobytes. But the main lever for file size is always quality and dimensions, not metadata.

What quality setting should I use?

For photos you are sharing online or via email, 75% to 80% is a good starting point. For images that will be printed, use 85% to 90%. For thumbnails or very small images, you can go as low as 60% to 70%. Open the image at your chosen quality and look at it on the device where it will be viewed — your eye is the best judge.