Aspect Ratio Calculator
Calculate new image dimensions while preserving aspect ratio from pixels, inches, or cm.
Supports Instagram (1080x1080), YouTube (1280x720), and print formats.
An aspect ratio is the proportional relationship between an image’s width and height, expressed as width:height. It defines the shape of the frame and determines how images print, display on screens, and crop to fit different formats.
Formulas: Aspect Ratio = Width : Height (simplified by GCD) GCD (Greatest Common Divisor) reduces the ratio to its simplest form. Cropped Width = Original Height × Target Ratio Cropped Height = Original Width ÷ Target Ratio Print dimension: Width (inches) = Pixel Width ÷ DPI
Common aspect ratios and their uses:
| Ratio | Decimal | Common Use |
|---|---|---|
| 1:1 | 1.00 | Instagram square, profile photos |
| 4:3 | 1.33 | Old TV, compact camera default |
| 3:2 | 1.50 | 35mm film, most DSLR/mirrorless |
| 16:9 | 1.78 | HD video, YouTube, widescreen TV |
| 5:4 | 1.25 | 8×10 print, 5×4 film |
| 2.39:1 | 2.39 | Anamorphic cinema widescreen |
| 9:16 | 0.56 | Vertical video (Reels, TikTok, Stories) |
Worked example — finding crop dimensions: Your camera captures 6000×4000 pixels (3:2 ratio). You want to share on Instagram (1:1 square).
Cropped size = 4000×4000 (centered, losing 1000 pixels on each side of width). Lost area = (6000×4000) − (4000×4000) = 24,000,000 − 16,000,000 = 8,000,000 pixels removed (33% of image)
To print a 4000×4000 crop at 300 DPI: Print size = 4000 ÷ 300 = 13.3 × 13.3 inches
Standard print sizes and their ratios:
| Print Size | Ratio | Fits 3:2 |
|---|---|---|
| 4×6 | 3:2 | Perfect fit |
| 5×7 | 5:7 | Crop needed |
| 8×10 | 4:5 | Crop needed |
| 11×14 | 11:14 | Crop needed |
| 16×20 | 4:5 | Crop needed |
Composition tip: When shooting with a 3:2 camera for eventual 4:5 (Instagram) or 16:9 (YouTube thumbnail) delivery, leave extra space on the sides or top/bottom to give yourself room when cropping. This technique is called shooting loose.