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Aspect Ratio Calculator

Calculate width or height for any aspect ratio, or find the ratio of your image. Presets for 16:9, 4:3, 21:9, 1:1, and more.

: = 1.78:1
px
px
1920 × 1080

16:9

2.07 MP

Common resolutions at this ratio

About This Tool

Aspect ratio is the proportional relationship between width and height. Whether you're resizing video for YouTube (16:9), cropping photos for Instagram (1:1 or 4:5), or designing UI for ultrawide monitors (21:9), you need to maintain the correct ratio to avoid distortion. This calculator works two ways. First, enter a width and aspect ratio to calculate the matching height (or enter height to get width). Second, enter any dimensions to find their aspect ratio — useful when you have an image and need to know what ratio it is. Presets for common ratios used in video (16:9, 4:3, 21:9), photography (3:2, 4:3), social media (1:1, 4:5, 9:16), and cinema (2.35:1, 1.85:1) make quick work of standard formats.

How to Use

1. Choose a mode: "Calculate Dimension" or "Find Ratio" 2. For Calculate Dimension: - Click a preset ratio or enter a custom ratio (e.g., 16:9) - Enter width OR height — the other calculates automatically - Lock the value you want to keep fixed 3. For Find Ratio: - Enter both width and height - See the simplified aspect ratio and common name (if recognized) 4. Copy the result or share via link

Formula

Calculate height from width: Height = Width ÷ (Ratio Width ÷ Ratio Height) Example: 1920 ÷ (16 ÷ 9) = 1920 ÷ 1.778 = 1080 Calculate width from height: Width = Height × (Ratio Width ÷ Ratio Height) Example: 1080 × (16 ÷ 9) = 1080 × 1.778 = 1920 Find aspect ratio (GCD method): Divide both dimensions by their Greatest Common Divisor Example: 1920×1080 → GCD is 120 → 1920÷120 : 1080÷120 = 16:9

Frequently Asked Questions

What aspect ratio is 1920x1080?
1920×1080 is 16:9, the standard HD/Full HD ratio. It's used for most TVs, YouTube videos, computer monitors, and streaming platforms. Common resolutions in 16:9 include 1280×720 (HD), 1920×1080 (Full HD), 2560×1440 (2K), and 3840×2160 (4K).
What aspect ratio is 1080x1920?
1080×1920 is 9:16, which is vertical/portrait 16:9. It's the standard for TikTok, Instagram Reels, YouTube Shorts, and smartphone video. Same ratio as 16:9 but rotated 90 degrees.
What is the difference between 16:9 and 4:3?
16:9 is wider (widescreen), while 4:3 is more square (standard). 16:9 has been the TV and video standard since the 2000s. 4:3 was used for older TVs and is still common in iPad displays, some cameras, and presentation slides. 16:9 shows more horizontal content; 4:3 shows more vertical.
What aspect ratio should I use for Instagram?
Instagram supports multiple ratios: 1:1 (square, classic Instagram), 4:5 (portrait, recommended for feed posts — shows larger), 1.91:1 (landscape), and 9:16 (Stories/Reels). For maximum visibility in the feed, use 4:5 portrait (1080×1350).
What is 21:9 aspect ratio used for?
21:9 (actually 64:27 or approximately 2.37:1) is ultrawide, used for cinema-style video and ultrawide monitors. Many movies are filmed in 2.35:1 or 2.39:1, which are close to 21:9. Ultrawide monitors (3440×1440, 2560×1080) use this ratio for immersive gaming and multitasking.
How do I calculate aspect ratio from dimensions?
Divide both width and height by their Greatest Common Divisor (GCD). For 1920×1080: GCD is 120, so 1920÷120=16 and 1080÷120=9, giving 16:9. For dimensions that don't simplify to a common ratio, express as a decimal (e.g., 1.78:1 for 16:9).
What aspect ratio is best for printing photos?
3:2 matches standard print sizes (4×6, 6×9, 8×12 inches) and is the native ratio of most DSLR cameras. 4:3 works for 8×10 and 16×20 prints. 5:4 is used for 8×10 and 16×20. Always check your target print size — cropping may be needed if ratios don't match.

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