Aspect Ratio Calculator
Calculate display aspect ratios and scale image and video dimensions proportionally.
Input Parameters
Live Result
Details
Steps
Compute Greatest Common Divisor: GCD(1920, 1080) = 120
Simplify Aspect Ratio: 1920 ÷ 120 : 1080 ÷ {gcd} = 16:9 (Decimal: 1.7778:1)
Scale Dimensions: Target Width 1280px scaled proportionally yields Height 720px
Quick Answer & Understanding Your Result
An Aspect Ratio Calculator determines the proportional relationship between an image or video's width and height (W:H), simplifying dimensions using the Greatest Common Divisor (GCD) and scaling pixel resolutions without distortion.
Standard Display & Social Media Ratios
- 16:9 (Widescreen Video): Standard for YouTube, desktop monitors, HDTV, and 4K UHD displays (1920 × 1080, 3840 × 2160).
- 9:16 (Vertical Mobile Video): Standard for TikTok, Instagram Reels, YouTube Shorts, and Stories (1080 × 1920).
- 4:3 (Traditional Standard): Classic television, iPad displays, and retro gaming monitors (1024 × 768, 1600 × 1200).
- 1:1 (Square Format): Instagram square posts, avatars, and profile icons (1080 × 1080).
- 21:9 (Ultrawide Cinema): Cinematic film formats and panoramic ultrawide monitors (2560 × 1080, 3440 × 1440).
Formula & Calculation Logic
Mathematical FormulaCalculates the Greatest Common Divisor (GCD) using the Euclidean algorithm to simplify width and height into their smallest whole integer ratio, then applies cross-multiplication for proportional resizing.
Step-by-Step Guide
Enter Original Dimensions
Input your image or video width and height in pixels (e.g., 1920 × 1080).
Select a Standard Preset or Custom Input
Choose from 16:9 Full HD, 9:16 Vertical Video, 21:9 Ultrawide, 4:3, or 1:1.
Enter Target Width or Height for Scaling
Input your desired target width (e.g., 1280px) or target height to calculate the missing proportional dimension.
Copy CSS & Tailwind Snippets
Export the resulting aspect-ratio CSS property and Tailwind utility class directly into your project.
Worked Examples Table
| Example | Input Values | Calculated Result | Explanation |
|---|---|---|---|
| Scaling 1080p Full HD (1920 × 1080) to 720p HD Width | GCD is 120, yielding 16:9. Target width of 1280px scales proportionally to 720px height with zero distortion. | ||
| Scaling 4K Ultrawide (3440 × 1440) for Web Display | Scaling width down by 50% reduces height proportionally from 1440px to 720px. |
Frequently Asked Questions
Evidence-Based Methodology & Authoritative References
W3C CSS Box Sizing Module Level 4 - aspect-ratio
Society of Motion Picture and Television Engineers (SMPTE Standards)
MDN Web Docs: aspect-ratio CSS Property
Standard: ISO / W3C / IETF Authoritative Domain Standard
Formula: Aspect Ratio = (Original Width / GCD) : (Original Height / GCD)
Last Reviewed: August 21, 2026
Primary Source: W3C CSS Box Sizing Module Level 4 - aspect-ratio
Reference Document: Society of Motion Picture and Television Engineers (SMPTE Standards)
Computation Privacy: 100% client-side 0ms computation, zero data retention
Calculated results are modeled based on standard scientific and mathematical formulas. Please verify with domain-specific technical documentation for specialized applications.
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Calculated results are modeled based on standard scientific and mathematical formulas. Please verify with domain-specific technical documentation for specialized applications.