What does a 16:9 aspect ratio mean?

A 16:9 ratio means that for every 16 units of width there are 9 of height — a proportion that produces a wide landscape shape. It is the standard for horizontal video on YouTube and television, and matches both 1920 × 1080 and 1280 × 720.

What ratio do vertical videos use?

Vertical video uses 9:16, the inverse of 16:9, most commonly at 1080 × 1920. YouTube Shorts, Instagram Reels and TikTok all use it, so one export serves all three.

How do I convert landscape footage to vertical without ruining it?

There are three options and all involve a compromise: crop the sides and lose the edges, add empty bands top and bottom and shrink the picture, or recompose by placing the footage in the upper part and using the space below for text. The last usually works best for talking-head content.

Planning

Aspect Ratio Calculator

Enter a width and height to get the ratio, then change either one to compute its partner.

ORIGINAL DIMENSIONS

Width Height

Ratio —

Decimal form —

NEW DIMENSIONS — FILL IN EITHER

New width New height

NEW HEIGHT = NEW WIDTH × (ORIGINAL HEIGHT ÷ ORIGINAL WIDTH)

What this is

An aspect ratio calculator reduces a width-to-height relationship to its simplest form, and works out new dimensions that preserve it. It comes up whenever an image or video has to be resized without being squashed: you fix one side, and the other has to follow. Doing it mentally is easy for 16:9, and quickly stops being easy for something like 1546:423.

The formula

new height = new width × (original height ÷ original width)

The ratio is reduced by the greatest common divisor of both sides.
Reversed: new width = new height × (original width ÷ original height).

How it works

A ratio is simplified by dividing both sides by their greatest common divisor, so 1920 × 1080 becomes 16:9. Some dimensions do not reduce to anything tidy — 1546 × 423 simplifies to numbers nobody recognises — and in those cases a decimal form such as 3.66:1 is more useful for comparison.

Changing a video's ratio means choosing between cropping and adding empty bands. Turning landscape footage vertical for Shorts throws away the left and right; adding black bars keeps the whole frame but reads as repurposed. Neither is correct in general — there is only which loss you can live with.

How to use it

Enter your original dimensions The simplified ratio and its decimal form appear immediately.
Fill in one new dimension Enter a new width and the height is computed, or the other way round.
Use a preset if one fits Common video, social and print ratios are available as shortcuts.

Common questions

What does a 16:9 aspect ratio mean?: A 16:9 ratio means that for every 16 units of width there are 9 of height — a proportion that produces a wide landscape shape. It is the standard for horizontal video on YouTube and television, and matches both 1920 × 1080 and 1280 × 720.
What ratio do vertical videos use?: Vertical video uses 9:16, the inverse of 16:9, most commonly at 1080 × 1920. YouTube Shorts, Instagram Reels and TikTok all use it, so one export serves all three.
How do I convert landscape footage to vertical without ruining it?: There are three options and all involve a compromise: crop the sides and lose the edges, add empty bands top and bottom and shrink the picture, or recompose by placing the footage in the upper part and using the space below for text. The last usually works best for talking-head content.

Notes

The calculation runs in your browser.