🖥️ Resolution & Aspect Ratio: Calculator

Find the simplified aspect ratio, megapixels, and matching dimensions for any resolution.

px
px
:
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ASPECT RATIO
16:9
Landscape
Megapixels
0 MP
Total Pixels
0
GCD Used
0
Decimal Ratio
0.00
Enter a target ratio and known dimension to solve for the other side.

How the Resolution & Aspect Ratio Calculator Works

Every image or video resolution has an underlying aspect ratio — the proportional relationship between its width and height. This calculator reduces your width and height to their simplest whole-number ratio using the greatest common divisor (GCD), the same method taught for simplifying fractions, computed here with the classic Euclidean algorithm. It also reports the total megapixel count, a common spec for cameras and displays.

GCD = Euclidean algorithm on (Width, Height)
Aspect Ratio = (Width ÷ GCD) : (Height ÷ GCD)
Megapixels = (Width × Height) ÷ 1,000,000

Finding a Missing Width or Height

The second tool below lets you go the other direction: if you know you want a specific aspect ratio (say, 16:9 or 4:3) and you already have one dimension locked in — for example, a fixed width for a video template — it calculates the matching height (or width) that preserves that exact ratio, using Height = Width × (Ratio-Height ÷ Ratio-Width), or the mirrored formula to solve for width instead.

Why Aspect Ratio Matters for Video and Photography

Common aspect ratios include 16:9 (standard widescreen video and most monitors), 4:3 (older TVs and some cameras), 1:1 (square, common on social media), and 21:9 (ultrawide cinematic format). Resizing an image or video without respecting its native ratio causes stretching or letterboxing, so knowing the exact reduced ratio helps you crop, resize, or export content correctly across different platforms and screen sizes.

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❓ Frequently Asked Questions

How is the aspect ratio actually calculated?
The calculator finds the greatest common divisor (GCD) of your width and height pixel values using the Euclidean algorithm, then divides both numbers by that GCD to get the simplest whole-number ratio, such as reducing 1920×1080 down to 16:9.
What does megapixels mean and why does it matter?
Megapixels (MP) is simply width × height divided by one million, giving the total pixel count in an image or frame. It's commonly used to describe camera sensor resolution and roughly indicates how much fine detail an image can capture.
Can I use this to find a matching resolution for a specific aspect ratio?
Yes. Use the 'Find a Missing Dimension' section: enter your target ratio (like 16:9) and a known width or height, and the calculator computes the other dimension needed to preserve that exact ratio.
What's the difference between 16:9 and 16:10?
16:9 is the standard widescreen ratio used by most TVs, monitors, and video platforms (e.g., 1920×1080). 16:10 is slightly taller and is common on some laptop and professional monitor displays (e.g., 1920×1200) — a small but noticeable difference in vertical screen space.
Does this work for video frame sizes as well as photos?
Yes, the same width/height and GCD-based ratio math applies equally to photo resolutions, video frame sizes, and display resolutions — anything described by a pixel width and height.

🏆 About This Tool — Accuracy & Trust

🔒 Data Privacy: All calculations run entirely within your browser using JavaScript. Nothing you enter here is ever transmitted to our servers, stored, sold, or shared.

📐 Accuracy Note: This tool uses standard, widely published formulas and guidelines. Results are estimates for informational purposes; for financial, medical, or engineering decisions, consult a licensed professional.

📅 Last Updated: September 2026.