Image File Size Calculator

Matching image size to platform limits

Most online platforms have hidden or documented file size limits. Hit them and your image either gets rejected, re-compressed heavily (losing quality), or fails to upload at all. Enter your target size in the calculator to find the maximum resolution that fits.

Common target sizes

• Under 100 KB: Email signatures, forum avatars, small web thumbnails. Typically 400–600 px wide.
• Under 500 KB: Blog post featured image at 1200 px wide, JPG quality 80. Fast load on mobile.
• Under 1 MB: Standard web photo at 1920 px wide, JPG quality 85. Balances quality and load time.
• Under 2 MB: YouTube thumbnail max (actually 2 MB JPG). High-detail blog images.
• Under 5 MB: Most job application portals for photo uploads. Professional headshots at full resolution.
• Under 10 MB: Government online services in many countries for ID document scans.
• Under 25 MB: Gmail/Outlook attachment limits. Roughly 5 full-resolution phone photos.

Strategies for hitting a target file size

When your image is too large, try these in order (least to most quality loss):

1. Strip metadata: Remove EXIF, GPS, thumbnail. Saves 10–200 KB.
2. Lower JPG quality: 100 → 85 halves the file; 85 → 70 halves it again with small visible loss.
3. Reduce resolution: Halving each dimension quarters the file size (2000×1500 → 1000×750 is 25% of original).
4. Convert format: PNG → JPG for photos (5–10× smaller); JPG → WebP (further 30% smaller).
5. Reduce bit depth: PNG-24 → PNG-8 (256 colors) for screenshots and icons.

Tool settings for common goals

• "Look sharp on retina phones": 1600 px on the long side, JPG quality 85. ~400 KB.
• "Fit inside email signature": 400 px, JPG quality 80. ~50 KB.
• "Printable from web page": 2480 px wide for A4 at 300 DPI, JPG quality 90. ~1.5 MB.
• "Instagram best quality": 1080 px wide (they compress to this anyway), JPG quality 90. ~300 KB.
• "Minimal quality loss archive": Original resolution, JPG quality 95. ~60% of uncompressed.

When to stop compressing

Compression artifacts become visible below roughly JPG quality 70. You'll see blockiness in smooth gradients (sky, skin), color banding, and halos around edges. If your target size requires going below quality 70, it's better to first reduce resolution and keep quality higher. For any file you might enlarge later (printing, re-editing), save a lossless original in PNG or TIFF alongside the compressed version.