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Aspect ratio calculator: resize while keeping proportions

Find the missing width or height for a given aspect ratio, or the simplified ratio of any image or screen size, in pixels or any other unit.

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Results

Width

1,920.0

Height

1,080.0

Ratio as a decimal (width ÷ height)
1.778 : 1
Simplified ratio: width part
16
Simplified ratio: height part
9
Megapixels (if in pixels)
2.07
Diagonal (same unit)
2,202.9

Height for other widths

HeightMegapixels (if in pixels)
640 current360.00.23
1,280 current720.00.92
1,920 current1,080.02.07
2,560 current1,440.03.69
3,840 current2,160.08.29
7,680 current4,320.033.18

What an aspect ratio is

The aspect ratio of an image, video or screen is the proportion between its width and its height, written width:height. A 16:9 frame is 16 units wide for every 9 units high, whatever its actual size: 1280 × 720, 1920 × 1080 and 3840 × 2160 are all 16:9. Keeping the ratio when you resize prevents stretched faces and black bars.

Three ways to use the calculator

  • Height from the width: pick a ratio and enter the width to get the matching height.
  • Width from the height: the reverse, useful for a banner of fixed height.
  • Ratio of a size: enter any width and height to get the simplified ratio, its decimal value, the megapixels and the diagonal.

The calculator works with pixels, inches, centimeters or any unit, as long as width and height use the same one.

The formulas

  • Ratio r = width ÷ height (16 ÷ 9 = 1.778)
  • Height = width ÷ r
  • Width = height × r
  • Simplified ratio: divide width and height by their greatest common divisor
  • Diagonal = √(width² + height²)

Worked example

You need a 16:9 thumbnail 1920 pixels wide.

  1. r = 16 ÷ 9 = 1.778.
  2. Height = 1920 ÷ 1.778 = 1080 pixels.
  3. The greatest common divisor of 1920 and 1080 is 120, so the ratio simplifies to 16:9.
  4. The image holds 1920 × 1080 = 2,073,600 pixels, or 2.07 megapixels.

Common aspect ratios

Ratio Decimal Typical use
16:9 1.78 HD and 4K video, TVs, monitors
16:10 1.60 Laptops
4:3 1.33 Older TVs, tablets, many compact cameras
3:2 1.50 35 mm photos, many DSLRs
21:9 2.33 Ultrawide monitors
1:1 1.00 Square social posts
4:5 0.80 Portrait feed posts
9:16 0.56 Vertical video, stories
2.39:1 2.39 Widescreen cinema

Cropping versus letterboxing

When a picture’s ratio does not match the screen, you either crop part of it or add bars. A 4:3 photo shown on a 16:9 screen gets bars on the sides (pillarboxing); a 2.39:1 film on the same screen gets bars at the top and bottom (letterboxing). To fill the frame without bars, crop to the target ratio before exporting.

Frequently asked questions

How do you calculate the height from an aspect ratio?

Divide the width by the ratio. For 16:9, the ratio is 16 ÷ 9 = 1.778, so a 1920-pixel-wide image is 1920 ÷ 1.778 = 1080 pixels high.

What is the aspect ratio of 1920 × 1080?

16:9. Divide both numbers by their greatest common divisor, 120: 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9.

What aspect ratio should I use for social media?

9:16 for vertical video such as stories and short clips, 1:1 or 4:5 for feed posts, and 16:9 for regular landscape video.

Is 16:10 the same as 16:9?

No. 16:10, common on laptops, is slightly taller: at 1920 pixels wide it is 1200 high instead of 1080, giving about 11% more vertical space.

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Results are estimates provided for information purposes. They do not replace professional advice.

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