Aspect Ratio Calculator
Calculate matching dimensions for any ratio. Free, no signup.
How It Works
Set the aspect ratio (for example 16:9) and enter a width in pixels. The matching height is calculated instantly using height = width × ratio‑height ÷ ratio‑width. Tap a preset button to load a common ratio. Because aspect ratio is unitless, the same result applies whether you work in pixels, inches, or centimeters — useful for sizing images, videos, banners, thumbnails, and responsive layouts.
Example: at 16:9, a width of 1920 gives a height of 1080. At 4:3, a width of 1024 gives a height of 768.
Common Aspect Ratios & Resolutions
| Ratio | Used for | Common resolutions |
|---|---|---|
| 16:9 | Widescreen video, monitors, YouTube | 3840×2160, 1920×1080, 1280×720 |
| 4:3 | Classic TV, iPad, presentations | 1024×768, 800×600 |
| 1:1 | Square — profile pics, Instagram | 1080×1080, 600×600 |
| 21:9 | Ultrawide monitors, cinema | 3440×1440, 2560×1080 |
| 9:16 | Vertical video — TikTok, Reels, Stories | 1080×1920, 720×1280 |
| 3:2 | DSLR photos, prints | 2160×1440, 1080×720 |
| 2:1 | Social banners, panoramas | 1200×600 |
How to Calculate Aspect Ratio From Width and Height
If you already know both dimensions and want the ratio, divide the width by the height and simplify to whole numbers. For example 1920 ÷ 1080 = 1.78, which simplifies to 16:9. A quick way to simplify is to divide both numbers by their greatest common divisor: 1920 and 1080 share a divisor of 120, giving 16:9.
Frequently Asked Questions
How do I calculate aspect ratio from width and height?
Divide the width by the height to get the ratio as a decimal, then simplify it to whole numbers by dividing both sides by their greatest common divisor. For example, 1920 x 1080 divides down to 16:9, and 1024 x 768 divides down to 4:3. This calculator does the reverse — you give it a ratio and one dimension, and it fills in the other.
What is the 16:9 aspect ratio in pixels?
16:9 is the standard widescreen ratio. Common 16:9 pixel resolutions are 3840x2160 (4K UHD), 2560x1440 (1440p), 1920x1080 (1080p / Full HD), 1280x720 (720p), and 854x480. Any width divisible by 16 works — multiply the width by 9 and divide by 16 to get the matching height.
How do I calculate the height for a given width?
Enter your target ratio (for example 16 and 9) and type the width in pixels. The matching height is calculated instantly using height = width x ratio-height / ratio-width. Use the preset buttons for common ratios like 16:9, 4:3, 1:1, and 21:9.
What is the 21:9 ultrawide aspect ratio?
21:9 is the ultrawide monitor and cinematic ratio. Typical 21:9 resolutions are 2560x1080, 3440x1440, and 5120x2160. It is wider than standard 16:9 and is used for ultrawide displays and letterboxed film.
Does this aspect ratio calculator work for inches or cm?
Yes. Aspect ratio is unitless, so the same calculation works for pixels, inches, centimeters, or any unit. Enter your width in whatever unit you are using and the height comes out in the same unit.