Screen Resolution & Aspect Ratio Calculator

What the screen Resolution & Aspect Ratio Calculator does

An aspect ratio is the relationship between width and height, written as two numbers in their lowest terms. 1920 × 1080 reduces to 16:9; 1024 × 768 reduces to 4:3. Two images with the same ratio have the same shape regardless of how many pixels they contain, which is why the ratio matters more than the resolution when you are deciding whether something will fit without stretching or cropping.

The main calculator solves for a missing dimension. Enter an original size and one new dimension, and the other is filled in at the same ratio. This is the everyday case: you know a video is 1920 × 1080 and you need it 1280 pixels wide, so what is the height? The answer is 720, and typing it yourself is how people end up with 1280 × 800 and a squashed picture.

Simplification is done with the greatest common divisor, so any resolution reduces to its exact lowest terms. Some real resolutions do not reduce neatly — 1366 × 768 is 683:384 exactly, which is useless to anyone — so where the exact ratio has awkward numbers the calculator also offers the closest friendly approximation, in that case 16:9.

Below the calculator, the table shows what standard widths become at your ratio, from nHD up to 8K, with the megapixel count for each. The optional pixel-density field turns a resolution and a screen diagonal into pixels per inch, which is the figure that actually determines whether a display looks sharp: about 110 PPI is a standard desktop monitor, 160 a sharp laptop, and 220 or above is retina-class at normal viewing distance.

How to use it

1. Enter the original width and height, or press one of the preset buttons.
2. Type the new width you need — the new height is calculated automatically, and vice versa.
3. Check the simplified ratio and, if you are sizing a physical display, add the screen diagonal for a PPI figure.
4. Use the standards table to find the nearest conventional resolution at your ratio.

A worked example

You have a 1920 × 1080 video and a container 1280 pixels wide:

Original    1920 × 1080
New width   1280
New height  720          ← calculated
Ratio       16:9
Megapixels  0.92 MP

Now a trickier case. A photograph is 4032 × 3024 and must fill a 1080 × 1350 portrait social post. Enter the original and set the new height to 1350, and the calculator returns a new width of 1800 — wider than the 1080 the slot allows. That is the useful answer: the shapes do not match (4:3 landscape versus 4:5 portrait), so you cannot resize your way there. You have to crop 720 pixels of width, and the Image Resizer & Cropper is where you decide which 720 pixels to lose.

Frequently asked questions