How to reduce image file size without losing visible quality

Big images slow down websites, bounce off email size limits and fill up phones. Three levers control file size; use them in this order.

Lever 1: dimensions (the biggest win)

File size grows with the number of pixels. A 12-megapixel phone photo (4000 × 3000) has four times more pixels than the same photo at 2000 × 1500, and a Full HD screen is only 1920 pixels wide.

Recommended maximum widths:

Use	Max width
Email attachment	1600–2000 px
Blog or website content image	1200–1600 px
Full-width website hero	1920–2560 px
Thumbnail	400–600 px

Use Resize image, or the Maximum size option in Compress image.

Lever 2: quality

JPEG and WebP are lossy formats: they discard detail the eye barely notices. The quality setting controls how much.

• 85–92: visually identical to the original. Use for portfolios and print.
• 70–80: the sweet spot for the web and email; differences are hard to spot.
• Below 60: artifacts appear around edges and in skies.

Lever 3: format

• JPG — photos. Universally supported.
• PNG — screenshots, logos and graphics with sharp edges or transparency. Lossless, so large for photos.
• WebP — both photos and graphics, with transparency, typically 25–35% smaller than JPG and much smaller than PNG. Supported by all current browsers. Convert with JPG to WebP or PNG to WebP.

Putting it together

A typical 6 MB phone photo, resized to 1920 px and saved at quality 75, ends up around 300–500 KB — more than ten times smaller, with no visible difference on screen.

Need an exact size in KB?

If a form demands “maximum 50 KB” (or even “minimum 20 KB”), use Resize image in KB: enter the target and it finds the best quality that fits — or increases the file size when it's below a required minimum.

Privacy bonus

Re-encoding an image removes its EXIF metadata, including GPS location. That's usually what you want before sharing photos publicly.