Aspect Ratio Calculator
Enter width and height to get the aspect ratio. Or pick a ratio and enter one dimension to find the other. Click any result to copy it.
Enter new width or height — the other dimension updates automatically to maintain the aspect ratio above. Clear width or height first to enter the new value.
Common Aspect Ratios
| Ratio | Decimal | Common Use | Example Resolutions |
|---|---|---|---|
| 16:9 | 1.778 | Widescreen HD / 1080p / 4K | 1920×1080, 2560×1440, 3840×2160 |
| 4:3 | 1.333 | Standard / Old TV / iPad | 1024×768, 800×600, 2048×1536 |
| 1:1 | 1.000 | Square / Instagram | 1080×1080, 2048×2048 |
| 21:9 | 2.333 | Ultra-wide / Cinematic | 2560×1080, 3440×1440 |
| 9:16 | 0.563 | Portrait / TikTok / Instagram Reel | 1080×1920, 720×1280 |
| 4:5 | 0.800 | Instagram Portrait | 1080×1350 |
| 3:2 | 1.500 | DSLR / 35mm Film | 3000×2000, 6000×4000 |
| 2:3 | 0.667 | Portrait 35mm / A4 paper approx | 2000×3000 |
| 16:10 | 1.600 | MacBook / Widescreen Laptop | 2560×1600, 1920×1200 |
| 5:4 | 1.250 | Old Monitor / Square-ish | 1280×1024 |
| 17:9 | 1.889 | Digital Cinema (DCI) | 4096×2160 |
| 2.39:1 | 2.390 | Anamorphic Cinema | 4096×1716 |
Frequently Asked Questions
What is aspect ratio?
Aspect ratio is the proportional relationship between the width and height of a rectangle, expressed as width:height (e.g., 16:9). It describes shape without specifying actual size. The same aspect ratio can describe a phone screen, a billboard, or a video frame.
How do I calculate aspect ratio?
Divide the width by the height to get the decimal ratio. Then simplify the fraction by dividing both numbers by their GCD. For example, 1920×1080: GCD is 120, so 1920÷120 = 16 and 1080÷120 = 9, giving 16:9.
What is 16:9 aspect ratio?
16:9 is widescreen — for every 16 units of width there are 9 units of height. It's the standard for HD and 4K video, most modern monitors, and YouTube. Common 16:9 resolutions: 1280×720, 1920×1080, 2560×1440, 3840×2160.
How do I maintain aspect ratio when resizing?
Enter your original width and height into the calculator. Then type the new width or height — the calculator automatically computes the other dimension to maintain the exact ratio. This prevents stretching or distortion.
What aspect ratio is 1080×1920?
1080×1920 is a 9:16 aspect ratio — portrait orientation, the inverse of 16:9 widescreen. This is the standard for vertical video on TikTok, Instagram Reels, and YouTube Shorts.
What aspect ratio is 4:3?
4:3 (also written 1.33:1) was the standard for older TVs and monitors. For every 4 units wide, the image is 3 units tall. Common resolutions: 800×600, 1024×768. Modern iPads use approximately 4:3.