16:9 Aspect Ratio Calculator

Enter a width, height, and screen diagonal to find the missing 16:9 dimension, simplify any width:height ratio, and get the physical screen size for a given diagonal.

Quick Facts

Formula
16:9 means width ÷ height = 16 ÷ 9 ≈ 1.778
Common 16:9 resolutions: 1280×720 (HD), 1920×1080 (Full HD), 2560×1440 (QHD), 3840×2160 (4K UHD).
Diagonal sizing
Diagonal, width, and height form a right triangle
For 16:9: width = diagonal × 16/√337, height = diagonal × 9/√337 (√337 ≈ 18.358).

Your Results

Calculated
Simplified ratio
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Width:Height in lowest terms
Height at 16:9
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For the width entered
Width at 16:9
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For the height entered
Physical screen size
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Width × height for the diagonal entered

Ready

Enter width, height, and diagonal size, then press Calculate.

About the 16:9 Aspect Ratio

Aspect ratio calculators convert between display dimensions, maintaining the width-to-height ratio that determines how content appears on screen.

How the calculator works

The tool applies three pieces of standard geometry. To find the height that matches a given width at 16:9, multiply the width by 9 and divide by 16: height = width × 9 ÷ 16. To go the other direction, multiply the height by 16 and divide by 9: width = height × 16 ÷ 9. To check whether an existing width and height are already 16:9, divide both by their greatest common divisor (GCD) — if the simplified fraction reduces to 16:9, the resolution is a true widescreen ratio. Finally, to convert a diagonal screen size into physical width and height, treat the diagonal as the hypotenuse of a 16-9 right triangle: width = diagonal × 16 ÷ √337 and height = diagonal × 9 ÷ √337, where √(16² + 9²) = √337 ≈ 18.358 (the Pythagorean theorem).

Common aspect ratios

  • 16:9 — standard widescreen for HD/4K TVs, monitors, YouTube, most video content
  • 4:3 — older TVs and monitors; still used in some photography and presentations
  • 1:1 — square format; Instagram, profile photos
  • 9:16 — vertical (portrait) video; Instagram Reels, TikTok, YouTube Shorts
  • 21:9 — ultrawide monitor and cinematic format

Practical uses

  • Calculating the height of an image or video given a fixed width (or vice versa) without stretching it
  • Checking whether an existing resolution is truly 16:9 or a close-but-different ratio like 8:5
  • Working out the physical width and height of a TV or monitor from its advertised diagonal size

Frequently Asked Questions

How do I calculate the height for a given width at 16:9?
Multiply the width by 9 and divide by 16 (height = width × 9 ÷ 16). For example, a width of 1920 gives a height of 1920 × 9 ÷ 16 = 1080. To go the other way, multiply height by 16 and divide by 9 (width = height × 16 ÷ 9).
How do I know if my resolution is really 16:9?
Divide width by height and compare it to 16 ÷ 9, which is about 1.778. Simplifying the width and height by their greatest common divisor also works: if it reduces exactly to 16:9, the resolution matches. 1920×1080 and 1280×720 both reduce to 16:9; 1920×1200 reduces to 8:5 and is not 16:9.
How do I get the physical width and height from a diagonal screen size?
Treat the diagonal as the hypotenuse of a 16-9 right triangle. Physical width = diagonal × 16 ÷ √337 and physical height = diagonal × 9 ÷ √337, where √337 ≈ 18.358. A 55 inch 16:9 screen works out to about 47.9 × 27.0 inches.
What are common 16:9 resolutions?
Frequently used 16:9 pixel resolutions include 1280×720 (HD/720p), 1920×1080 (Full HD/1080p), 2560×1440 (QHD/1440p), and 3840×2160 (4K UHD). Each keeps the same width-to-height ratio, so scaling between them does not distort the image.

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