Image Size & Dimension Calculator
Calculate pixel dimensions, aspect ratio, and physical print conversions instantly.
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Enter pixel dimensions or physical inches/cm to calculate DPI and print sizes directly.
Pixels, Inches, Centimeters and DPI Explained
Understanding the relationship between digital pixels and physical print dimensions is straightforward once you know the density formula:
• Pixels = Physical size in inches × DPI
• Physical size in inches = Pixels ÷ DPI
• Centimeters to pixels = (Centimeters ÷ 2.54) × DPI
For instance, an 8 × 10 inch photo print targeted at 300 DPI requires 2400 × 3000 pixels (8 × 300 by 10 × 300). Similarly, an A4 document (21.0 × 29.7 cm / 8.27 × 11.69 in) at 300 DPI requires approximately 2480 × 3508 pixels.
Keep in mind that changing DPI metadata alone does not invent or create additional pixels. If your image file contains fewer pixels than required for your target print size, you can check its maximum printable size with our print size calculator.
How to Calculate Pixels for a Print Size
If you know the physical size of the frame or paper you want to fill, use the target DPI to determine the required pixel dimensions before designing or printing:
| Print Size (Inches) | Metric Size (cm) | Required Pixels at 300 DPI | Total Megapixels |
|---|---|---|---|
| 4 × 6 in | 10.2 × 15.2 cm | 1200 × 1800 px | 2.16 MP |
| 5 × 7 in | 12.7 × 17.8 cm | 1500 × 2100 px | 3.15 MP |
| 8 × 10 in | 20.3 × 25.4 cm | 2400 × 3000 px | 7.20 MP |
| 11 × 14 in | 27.9 × 35.6 cm | 3300 × 4200 px | 13.86 MP |
| 12 × 18 in | 30.5 × 45.7 cm | 3600 × 5400 px | 19.44 MP |
| 16 × 20 in | 40.6 × 50.8 cm | 4800 × 6000 px | 28.80 MP |
For a full reference of poster and document sizes, explore our 300 DPI image size chart. If your existing image does not match your target dimensions, you can resize and crop it using our free image resizer.
Print Bleed and Extra Pixels
Commercial printing workflows often require a small margin called "bleed" around the outer edges so that trimmed paper does not show white borders. Bleed specifications vary by print provider and product type.
For example, some commercial print shops specify a 3 mm (approx. 0.125 in) bleed on all four sides. For an 8 × 10 in print with a 0.125 in bleed on each side, the total pre-trim canvas size becomes 8.25 × 10.25 in, requiring 2475 × 3075 pixels at 300 DPI. Always verify the exact bleed requirements with your printer before finalizing artwork.
Frequently Asked Questions
Divide the pixel width and height by your intended DPI. For example, 3000 pixels divided by 300 DPI equals 10 inches of physical print width.