What this calculator covers
- Any width and height greater than 0 and up to 1,000,000,000, with up to 6 decimal places. Ratios such as 2.39 : 1 can be typed as width 2.39 and height 1.
- Units: pixels, inches, centimeters, millimeters or no units. The ratio has no unit; the new size and diagonal use the unit you pick.
- 36 resolution presets (video and TV, DCI digital cinema, computer monitors, social and photo sizes) and 25 common aspect ratios.
- SD presets (720 × 480 and 720 × 576) use the stored pixel size. SD video often uses non-square pixels and is shown at 4:3 or 16:9; this calculator does not model pixel aspect ratio.
- Everything is calculated in your browser. There is no image upload: you type the numbers or pick a preset.
Aspect ratio chart
Common aspect ratios with their decimal value and the resolution presets above that match them exactly.
| Ratio | Decimal | Name | Presets with this ratio |
|---|---|---|---|
| 1:1 | 1:1 | Square | 1080 × 1080 (Square post) |
| 1.19:1 | 1.19:1 | Movietone | — |
| 5:4 | 1.25:1 | — | 720 × 576 (SD PAL), 1280 × 1024 (SXGA) |
| 4:3 | 1.333:1 | Standard | 640 × 480 (VGA), 800 × 600 (SVGA), 1024 × 768 (XGA), 4000 × 3000 (4:3 photo) |
| 1.375:1 | 1.375:1 | Academy | — |
| 1.43:1 | 1.43:1 | IMAX | — |
| 3:2 | 1.5:1 | — | 720 × 480 (SD NTSC (DV)), 6000 × 4000 (3:2 photo) |
| 16:10 | 1.6:1 | — | 1280 × 800 (WXGA), 1440 × 900 (WXGA+), 1680 × 1050 (WSXGA+), 1920 × 1200 (WUXGA), 2560 × 1600 (WQXGA) |
| 5:3 | 1.667:1 | — | — |
| 16:9 | 1.778:1 | Widescreen | 1280 × 720 (HD 720p), 1920 × 1080 (Full HD 1080p), 2560 × 1440 (QHD 1440p), 3840 × 2160 (4K UHD), 7680 × 4320 (8K UHD), 1600 × 900 (HD+), 5120 × 2880 (5K), 6016 × 3384 (6K) |
| 1.85:1 | 1.85:1 | Flat | 1998 × 1080 (2K Flat), 3996 × 2160 (4K Flat) |
| 256:135 | 1.896:1 | DCI full container | 2048 × 1080 (2K Full), 4096 × 2160 (4K Full) |
| 2:1 | 2:1 | Univisium | — |
| 2.2:1 | 2.2:1 | 70mm | — |
| 21:9 | 2.333:1 | — | — |
| 2.35:1 | 2.35:1 | Scope classic | — |
| 64:27 | 2.37:1 | Ultrawide (sold as 21:9) | 2560 × 1080 (Ultrawide FHD), 5120 × 2160 (5K2K ultrawide) |
| 2.39:1 | 2.39:1 | Scope | — |
| 2.4:1 | 2.4:1 | — | — |
| 2.55:1 | 2.55:1 | CinemaScope | — |
| 2.76:1 | 2.76:1 | Ultra Panavision | — |
| 32:9 | 3.556:1 | Super ultrawide | 5120 × 1440 (Super ultrawide DQHD) |
| 9:16 | 0.563:1 | Vertical | 1080 × 1920 (Vertical video) |
| 4:5 | 0.8:1 | Portrait | 1080 × 1350 (Portrait post) |
| 2:3 | 0.667:1 | Portrait | — |
| 1024:429 | 2.387:1 | — | 2048 × 858 (2K Scope), 4096 × 1716 (4K Scope) |
| 683:384 | 1.779:1 | — | 1366 × 768 (HD laptop) |
| 43:18 | 2.389:1 | — | 3440 × 1440 (Ultrawide QHD) |
| 40:21 | 1.905:1 | — | 1200 × 630 (Link preview) |
How the aspect ratio is calculated
Simplified ratio
Divide the width and height by their greatest common divisor. 1920 × 1080 has a greatest common divisor of 120, so the ratio is 16:9. Decimal inputs are first multiplied by a power of 10 so both numbers are whole: 2.39 × 1 becomes 239:100.
Decimal ratio
Width ÷ height, shown to 3 decimal places. 1920 ÷ 1080 = 1.778, written 1.778:1.
Resize to a new width or height
New height = new width × original height ÷ original width. New width = new height × original width ÷ original height. The result is rounded the way you choose: whole numbers, even numbers or 2 decimals. If rounding changes the ratio, the calculator shows by how much.
Nearest standard ratio
The calculator compares your ratio with the 25 ratios in the chart and picks the one with the smallest difference (compared as landscape, then turned back if your size is portrait). The difference is shown as a percentage of width.
Fitting on another screen
If the picture is wider than the screen it gets bars at the top and bottom (letterbox); if it is narrower it gets bars at the sides (pillarbox). Share of the screen used = the smaller of (picture ratio ÷ screen ratio) and (screen ratio ÷ picture ratio). Pick a screen resolution to see the picture size and bar size in pixels.
Diagonal
Diagonal = √(width² + height²). The angle is measured from the bottom edge: arctan(height ÷ width).
FAQ
How do I determine the aspect ratio of an image or screen?
Type its width and height into the original size fields. The calculator shows the simplified ratio, the decimal ratio and the nearest standard ratio. It works as an image aspect ratio calculator, a screen aspect ratio calculator or a plain aspect ratio finder: only the two numbers matter.
How do I resize without changing the aspect ratio?
Keep the original size, then type the new width or the new height. The other side is calculated from the same ratio. For example 1920 × 1080 resized to a width of 1280 gives 1280 × 720.
Can I use it as an aspect ratio converter or generator?
Yes. Pick a ratio from the presets (or type it, such as 4 and 5), then type the width or height you need to get the matching dimension.
Why is 2560 × 1080 shown as 64:27 and not 21:9?
2560 ÷ 1080 = 2.370, and 64:27 is that size in whole numbers. These monitors are sold as 21:9, which is 2.333, so the two are close but not equal.
Why round to even numbers?
Video encoded with 4:2:0 chroma subsampling needs an even width and height. Choose "even numbers" when you size video.
Does this image ratio calculator upload my image?
No. There is no file upload. You enter the numbers, and the calculation runs in your browser.