Compress Images on Mac, Windows, iPhone & Android — Every Format Explained

Compression by Platform

Device	Built-In Option?	Quality Control?	Better Alternative
Mac	Preview (Export with quality slider)	Basic (no file size target)	Browser tool for precise KB targeting
Windows	None built-in	—	Browser tool (only free option)
iPhone	None (Mail app auto-compresses)	—	Browser tool in Safari
Android	None built-in	—	Browser tool in Chrome
Chromebook	None	—	Browser tool (only option)

Mac is the only platform with any built-in compression — and it is limited. Every other platform requires a third-party tool or browser solution.

The Format Trick That Beats Compression

Before adjusting quality settings, check if a format conversion gives you more savings:

Conversion	Size Reduction	When to Do This
PNG → JPG	3-5× smaller	Photos saved as PNG (common mistake)
JPG → WebP	25-35% smaller	Website images (all modern browsers)
HEIC → JPG	Stays similar or slightly larger	Compatibility (not size reduction)
BMP/TIFF → JPG	10-20× smaller	Legacy scan formats

Converting a photo from PNG to JPG at 85% quality often reduces file size by 80-90% — more than any quality slider can achieve within the same format. Use the Image Converter for format changes, then the Image Compressor for fine-tuning.

Mac-Specific Tips

Mac Preview's compression: open image → File → Export → drag the Quality slider. The preview shows estimated file size. This works but:

• No batch processing — one image at a time
• No precise file size target ("get this under 200KB")
• Only works with JPG quality — cannot optimize PNG

For precise control or batch processing, the browser-based compressor is more capable. Open it in Safari — same Mac, better tool.

iPhone & Android: The Mobile Workflow

Modern phone photos are 3-8MB each. When you need to send them via email (which typically limits attachments to 20-25MB total):

1. Open the Image Compressor in Safari (iPhone) or Chrome (Android)
2. Select photos from your camera roll
3. Set quality to 80-85% — the sweet spot for invisible quality loss with maximum size reduction
4. Download compressed versions — typically 600KB-1.2MB each instead of 3-8MB

The compressed photos look identical on phone screens. The file size difference only matters for sending and uploading.

Compression Settings by Use Case

Use Case	Format	Quality	Expected Size (per image)
Email attachment	JPG	80-85%	200KB-800KB
Website images	WebP	80%	80-300KB
Social media	JPG	85%	200-500KB
Professional printing	JPG or TIFF	95-100%	1-5MB
Archival/backup	PNG or original	Lossless	Original size