Math calculator
Aspect Ratio Calculator
Resize width and height to keep an aspect ratio, or find the ratio of any size.
Quick answer
How do you calculate aspect ratio?
Divide the width and height by their greatest common divisor. 1920 × 1080 ÷ 120 = 16:9. To resize, new height = new width × 9 ÷ 16, so 1280 wide gives 720 tall.
- Find the greatest common divisor of width and height.
- Divide both by it to get the ratio (1920×1080 → 16:9).
- To resize: new height = new width × ratio height ÷ ratio width.
- Example: 16:9 at 1280 px wide → 720 px tall.
New height = new width × (ratio height ÷ ratio width) • Ratio = width ÷ GCD : height ÷ GCD
⚡ Answer updates as you type · Enter = calculate · Esc = reset
Find the ratio of a size
1,920 × 1,080 = 16:9 (1.7778:1)
Resize images and video while keeping the same aspect ratio, or find the ratio of any width × height like 1920×1080 = 16:9.
About this Aspect Ratio Calculator
The Aspect Ratio Calculator resizes images, videos and screens without stretching them. Pick a ratio like 16:9 or 9:16, enter a width or height, and get the matching size — or enter any width × height to find its ratio.
What you'll need
- • Ratio width and height (or preset)
- • Known width or height
- • Any pixel size to simplify
How it works
- 1. Pick a preset or type a ratio.
- 2. Choose width or height.
- 3. Enter the size in pixels.
- 4. Read the matching side and preview.
- 5. Find the ratio of any size below.
Worked example
A 9:16 vertical video at 1080 px wide needs 1920 px height. 2560 × 1440 simplifies to 16:9.
Related searches
Aspect Ratio Calculator FAQ
What is the Aspect Ratio Calculator?
The Aspect Ratio Calculator is a free online tool that helps you resize width and height to keep an aspect ratio, or find the ratio of any size.
How do I use the Aspect Ratio Calculator?
Open the Aspect Ratio Calculator, enter the requested values, and review the instant estimate on the page.
Is the Aspect Ratio Calculator free?
Yes. The Aspect Ratio Calculator is free to use on Fast Online Calculator and does not require an account.
What is a 16:9 aspect ratio?
Width is 16 units for every 9 units of height. Common sizes: 1280×720, 1920×1080, 3840×2160.
What size is 9:16?
Vertical video for TikTok, Reels and Shorts — usually 1080 × 1920 pixels.
What aspect ratio is 1080 × 1350?
4:5, the Instagram portrait size.
Does changing aspect ratio stretch the image?
Only if width and height change by different amounts. Keeping the same ratio resizes without distortion.
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