1. 16:9 (1.78:1) - The Universal Widescreen.

Devices: Most modern smartphones, laptops, monitors, TVs, YouTube videos.
Why it's popular: Matches HD/4K video standards, efficient for landscape content.
Common resolutions: 1920×1080 (Full HD), 2560×1440 (2K/QHD), 3840×2160 (4K UHD), 1280×720 (HD).

2. 4:3 (1.33:1) - The Classic Digital Ratio.

Devices: Older digital cameras, tablets (iPad standard), some point-and-shoots.
Characteristics: Taller than 16:9, shows more vertical content.
Common resolutions: 1600×1200, 2048×1536, 3264×2448.

3. 3:2 (1.5:1) - DSLR/Mirrorless Standard.

Devices: Most DSLR and mirrorless cameras (Canon, Nikon, Sony, Fujifilm).
Advantage: Matches 4×6" print size perfectly, balanced composition.
Common resolutions: 6000×4000 (24MP), 4000×2667 (≈10.6MP), 3000×2000 (6MP).

4. 1:1 - The Square.

Devices/Platforms: Instagram (classic), some medium format cameras.
Use cases: Social media, album covers, artistic compositions.
Common resolutions: 1080×1080 (Instagram standard), 2048×2048, 3000×3000.

5. 6. 21:9 (2.33:1) - Ultra-Wide/Cinema.

Devices: Gaming monitors, some premium smartphones, cinema screens.
Use: Movies, immersive gaming, productivity (multiple windows).
Resolutions: 2560×1080, 3440×1440 (UWQHD).


Photo size is in the form of nR where n represents the shorter side of the photo and n is in inches. Eg, 4R size is 4 inches by 6 inches. For 10 inches and below, the longer side is 2 inches longer than the shorter side For 11 inches and above, the longer side is 3 inches longer than the shorter side.

1. Common Photo Print Sizes & Applications.

A. Small Prints (Snapshots & Casual Use)
Sizes: 2 × 2 inches (Passport photos); 3.5 × 5 inches (Standard snapshot); 4 × 6 inches (Most common photo print).
Resolution: 300 DPI (600 × 900 pixels for 2×3").
Best For: Wallet-sized photos; Quick prints (drugstores, kiosks); Scrapbooking, DIY projects..
B. Medium Prints (Framing & Display).
Sizes: 5 × 7 inches (Common for portraits); 8 × 10 inches (Popular for framing); 8.5 × 11 inches (Letter size, photo books).
Resolution: 300 DPI (2400 × 3000 pixels for 8×10").
Best For: Home/office photo frames; Greeting cards, invitations; Small posters or art prints.
C. Large Prints (Wall Art & Professional Use).
Sizes: 11 × 14 inches (Gallery-style prints); 16 × 20 inches (Poster size); 18 × 24 inches (Large posters, canvas).
Resolution: 300 DPI (4800 × 6000 pixels for 16×20").
Best For: Wall decor (homes, offices); Wedding/event photography; Fine art prints.
D. Extra-Large Prints (Commercial & Decorative).
Sizes: 20 × 30 inches (Poster, canvas wrap); 24 × 36 inches (Movie poster size); 30 × 40 inches+ (Billboards, murals).
Resolution: 150–300 DPI (varies by viewing distance).
Best For: Trade show banners; Store/wall murals; Museum/gallery exhibitions.

2. Specialty Print Sizes.

Square Prints (1:1 Ratio): 6 × 6 inches (Instagram-style prints); 12 × 12 inches (Scrapbook/album layouts).
Panoramic Prints (Wide Aspect Ratios): 4 × 12 inches (Landscape panoramas); 8 × 24 inches (Scenic wall art).

3. Key Factors for Printing Quality.

① DPI (Dots Per Inch).
300 DPI: Standard for high-quality prints (viewed up close).
150 DPI: Acceptable for large posters (viewed from a distance).
72 DPI: Only suitable for digital screens, not printing.
②. Aspect Ratio.
Match the camera’s ratio (e.g., 3:2 for DSLRs, 4:3 for smartphones).
Cropping may be needed for non-standard sizes (e.g., 8×10 from a 4×6).
③. File Format.
JPEG: Best for most photo prints (compressed but high quality).
TIFF/PNG: Lossless formats for professional editing/printing.
RAW: Used for advanced editing before conversion.

4. Application Scenarios.

Print Size: 2 × 3" – 4 × 6". Best Use Case: Snapshots, albums, ID photos.
Print Size: 5 × 7" – 8 × 10". Best Use Case: Framed portraits, certificates, gifts.
Print Size: 11 × 14" – 16 × 20". Best Use Case: Wall art, wedding photos, exhibitions.
Print Size: 20 × 30"+ . Best Use Case: Posters, banners, large-scale decor.