Aspect Ratio Calculator – Calculate & Convert Ratios Free
Calculate aspect ratios, scale dimensions, and find equivalent sizes for any image or video online. Includes common presets, social media sizes, and a visual proportion display—free and instant.
About This Tool
Learn what makes this tool special
What Is Aspect Ratio?
Aspect ratio is the proportional relationship between width and height, expressed as W:H (e.g., 16:9). The same ratio can apply to any size: 1920×1080, 1280×720, and 640×360 are all 16:9.
Common Aspect Ratios
| Ratio | Common Use |
|-------|------------|
| 16:9 | Widescreen video, YouTube, TV |
| 4:3 | Traditional TV, old monitors |
| 1:1 | Instagram posts, profile photos |
| 9:16 | Mobile video, TikTok, Stories |
| 21:9 | Ultrawide monitors, cinema |
| 3:2 | DSLR photos, MacBook screens |
| 4:5 | Instagram portrait |
Two Calculation Modes
1. From dimensions: enter width and height → get the simplified ratio
2. From ratio: enter the ratio and one dimension → get the missing dimension
Use Cases
- Resize images without distortion
- Find correct crop dimensions for social media
- Calculate video export dimensions
- Verify screen or print proportions
Key Features
What makes this tool special
- Calculate aspect ratio from width and height
- Get width or height from a known ratio and one dimension
- Common preset ratios (16:9, 4:3, 1:1, 9:16, 3:2, 21:9)
- Ratio simplification using GCD
- Decimal and pixel precision output
- Copy ratio or dimensions to clipboard
- No sign-up required
- Free with no limits
- Mobile-friendly
- Instant calculations
Quick Guide
Master this tool in seconds
- 1To find a ratio: enter the width and height of your image or video
- 2To find missing dimensions: select a preset ratio or enter a custom ratio, then enter either width or height
- 3The missing dimension or ratio is calculated instantly
- 4Copy the result to use in your design or video editor
Common Questions
Everything you need to know
Q.What does 16:9 aspect ratio mean?
For every 16 units of width, the height is 9 units. Standard widescreen HD video (1920×1080, 1280×720) is 16:9.
Q.How do I maintain aspect ratio when resizing?
Enter your known dimension and the tool calculates the other dimension to maintain the exact ratio.
Q.What aspect ratio is 1080×1920?
1080×1920 simplifies to a 9:16 aspect ratio — standard for vertical/portrait mobile video (TikTok, Instagram Stories).
Q.What is the aspect ratio of a 4K video?
Standard 4K (3840×2160) is 16:9 — the same ratio as 1080p HD, just at four times the pixel density.
Q.Is 4:3 or 16:9 better for YouTube?
YouTube uses 16:9. Videos in 4:3 will have black bars on the sides when played on YouTube.
Q.Is this tool free?
Yes — completely free with no sign-up.
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