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Aspect Ratio Calculator

Calculate, simplify, and scale aspect ratios for video, photo, and design.

Common Ratios
Current Dimensions
×
Ratio
16:9
Visual Preview
240px × 135px
160px × 90px
80px × 45px
Scale to new size

Common aspect ratios and their uses

Aspect ratios are fundamental to any visual medium. Using the wrong ratio means images get cropped, stretched, or letterboxed — none of which is ideal. Here is a quick reference for the most common formats:

  • 16:9 — YouTube, HD/4K video, most monitors and TVs
  • 9:16 — Instagram Reels, TikTok, YouTube Shorts (vertical video)
  • 1:1 — Instagram feed posts, profile pictures, app icons
  • 4:5 — Instagram portrait posts (maximises feed real estate)
  • 4:3 — Classic photos, older monitors, iPad screens
  • 3:2 — DSLR and mirrorless camera sensors (35mm film heritage)
  • 2:3 — Portrait photography, A4/A3 paper is approximately this
  • 21:9 — Ultrawide monitors, cinematic video format

Scaling dimensions without distortion

To scale any image or video to a new size without distortion, you must maintain the aspect ratio. The formula is simple: new_height = new_width ÷ (original_width ÷ original_height). This calculator automates that for you — just enter one dimension and get the other instantly.

Frequently asked questions

What is an aspect ratio?
An aspect ratio describes the proportional relationship between an image or video's width and height. It is expressed as W:H — for example, 16:9 means the width is 16 units for every 9 units of height. Aspect ratios are used in photography, video production, UI design, and printing to ensure consistent proportions across different sizes.
What is the 16:9 aspect ratio used for?
16:9 is the standard widescreen format used for HD and 4K video, YouTube, TV broadcasts, and most laptop/monitor displays. Common 16:9 resolutions include 1280×720 (720p), 1920×1080 (1080p), 2560×1440 (1440p), and 3840×2160 (4K UHD).
What aspect ratio should I use for Instagram?
Instagram supports multiple aspect ratios depending on the content type: 1:1 (square posts), 4:5 (portrait posts — shows largest in the feed), 1.91:1 (landscape posts), and 9:16 (Stories and Reels — full-screen vertical).
How do I calculate a new width from a given height (or vice versa)?
Use the Scale section of this calculator. Enter your known dimension, choose whether you are locking the height (to find the matching width) or locking the width (to find the matching height), and the calculator instantly shows the result.
What is the difference between 4:3 and 16:9?
4:3 is the classic 'TV' format used before widescreen — it is nearly square. 16:9 is the modern widescreen format, significantly wider. If you have a 4:3 image (e.g., 1024×768) and want to display it in a 16:9 container, you will need to crop, add letterboxing, or distort the image.

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