Enter width and height in pixels to calculate the aspect ratio, or enter a ratio and pixels to calculate dimensions.
Select presets for YouTube, Instagram, TikTok, etc. to set commonly used sizes with one click.
An online tool for calculating and converting image and video aspect ratios. Compute ratios from width and height, or calculate dimensions for a target aspect ratio.
Supports standard ratios like 16:9, 4:3, 1:1, and custom ratio calculations. Streamlines dimension calculations needed for design and video editing workflows.
All processing runs entirely in your browser. No data is ever sent to any server.
๐ฐ How to Use
Enter Width and Height
Input the pixel dimensions (width ร height) of your image or video.
Check the Aspect Ratio
The aspect ratio is automatically calculated. The simplified ratio using GCD is also displayed.
Convert Dimensions
Specify a target aspect ratio and calculate the corresponding size from width or height.
๐ Glossary
Aspect Ratio
The proportional relationship between width and height of an image or screen. Common ratios include 16:9 (widescreen) and 4:3 (standard).
16:9
The most common widescreen ratio, used for Full HD (1920ร1080) and 4K (3840ร2160).
4:3
Traditional monitor/TV ratio. Still used for presentations.
1:1
Square format. Used for Instagram feed posts and icon images.
9:16
Smartphone portrait ratio. Used for TikTok, Instagram Reels, and vertical videos.
Resolution
A measure of image/screen detail, expressed as "width pixels ร height pixels" (e.g., 1920ร1080). Different resolutions with the same aspect ratio produce different image quality.
Letterbox / Pillarbox
Black bars that appear when displaying content with a mismatched aspect ratio. Horizontal bars (letterbox) appear for widescreen on 4:3 displays; vertical bars (pillarbox) appear for 4:3 on widescreen.
Crop / Trim
Cutting away unwanted parts of an image. Also used to change aspect ratiosโfor example, trimming the sides of a 16:9 image to create a 4:5 crop.
Safe Zone
In vertical video formats (Stories, Reels), the area not covered by UI elements (username, like button, etc.). Typically 150โ250px margins from top and bottom; keep important content centered.
OGP Image (Open Graph Protocol)
Preview image displayed when sharing a URL on social media. Facebook recommends 1200ร630px (1.91:1). Twitter Cards and LINE use similar dimensions.
DPI / PPI (Dots/Pixels Per Inch)
Dots or pixels per inch. Print requires 300+ DPI. Web/screen standard is 72โ96 PPI, but Retina displays need 2ร (144โ192 PPI equivalent) images.
โ FAQ
Q. Does aspect ratio affect SEO?
A. OGP images (1.91:1 recommended) and platform-specific sizes affect display quality, so proper settings matter.
Q. Can I calculate video aspect ratios too?
A. Yes. Videos and images use the same calculation method for ratios.
Q. What is the relationship between DPI and pixels?
A. DPI indicates print resolution; pixels indicate screen size. This tool uses pixel-based calculations.
Q. Is my data sent to a server?
A. No. Everything runs in your browser.
Q. Can I use this on mobile?
A. Yes. Fully responsive.
๐ก Use Cases
๐ผ๏ธ
Image Production
Create banners and thumbnails with precise aspect ratios.
๐ฌ
Video Editing
Calculate dimensions for YouTube (16:9), TikTok (9:16), and other platforms.
๐ฑ
Responsive Design
Calculate ratios for the CSS aspect-ratio property.
๐จ๏ธ
Print Design
Calculate ratios for photo and poster print sizes.
๐ What is Aspect Ratio? Fundamentals
Aspect ratio is the "width-to-height proportion" of a screen or image
Aspect ratio refers to the proportional relationship between the width and height of a display, image, or video. For example, 16:9 means the width is 16 units for every 9 units of height. It is a critical parameter across all mediaโTV monitors, smartphones, video production, image editing, social media posts, and ad creatives. Choosing the correct aspect ratio prevents image cropping and letterboxing, ensuring optimal content display.
Common aspect ratios and their uses
16:9 (widescreen) is the standard for YouTube, TV, and PC monitorsโthe most versatile. 4:3 is the traditional ratio for older TVs and presentations (PowerPoint). 1:1 (square) is popular for Instagram and social media icons. 9:16 (portrait) is standard for TikTok, Instagram Reels, and YouTube Shorts. 4:5 is recommended for Instagram feed posts for maximum screen coverage. 3:2 is standard for DSLR cameras and photo prints. 21:9 (ultrawide) is used in cinema and ultrawide monitors. 2.35:1 (CinemaScope) is used for ultra-wide cinematic shots.
The recommended aspect ratio is 16:9. Uploading other ratios adds letterboxing automatically. Key resolutions: 2160p (4K): 3840ร2160px โ highest quality for large screens. 1440p (2K): 2560ร1440px โ good balance of quality and file size. 1080p (Full HD): 1920ร1080px โ the most standard and recommended. 720p (HD): 1280ร720px โ maintains HD while saving bandwidth.
YouTube Shorts
The recommended size is 9:16 (1080ร1920px). 1:1 is also accepted but won't display full-screen. Maximum duration is 60 seconds.
YouTube Thumbnails
Recommended: 16:9 (1280ร720px). Minimum width 640px, max 2MB. JPG, GIF, PNG supported. Use large readable text and expressive photos for better CTR.
๐ Instagram Post, Story & Reel Recommended Sizes
Instagram Feed Post Sizes
Three aspect ratios are supported: Portrait (4:5): 1080ร1350px โ highest feed screen coverage, most recommended. Square (1:1): 1080ร1080px โ classic size for unified profile grids. Landscape (1.91:1): 1080ร566px โ suits landscape photos but takes less feed space. Width resolution range: 320โ1080px.
Instagram Stories & Reels
Both use 9:16 (1080ร1920px) for full-screen display. Keep important content within the center 1080ร1610px area, as UI elements overlay the top and bottom ~155px.
Instagram Carousel Tips
The first image's aspect ratio applies to all. Use consistent ratiosโ4:5 (1080ร1350px) is most effective.
๐ TikTok, X (Twitter), Facebook, Pinterest & LINE Recommended Sizes
TikTok
Optimized for portrait: 9:16 (1080ร1920px). 1:1 and 16:9 supported but 9:16 provides the most immersive experience. File size limits: iOS 287MB, Android 72MB.
Photo post: 1200ร1200px (1:1). Link preview (OGP): 1200ร630px (1.91:1). Stories: 1080ร1920px (9:16). Cover photo: desktop 820ร312px, mobile 820ร462px (recommended 1125ร633px). Most versatile: 1080ร1080px (1:1).
Pinterest
Standard Pin: 1000ร1500px (2:3). Square Pin: 1000ร1000px (1:1). Idea ads: 1080ร1920px (9:16).
๐ Aspect Ratios in Cinema, Film & Monitors
Standard TV/Monitor Aspect Ratios
16:9 is the current standard for digital broadcasting, YouTube, Netflix, etc. Resolutions include HD (1280ร720), Full HD (1920ร1080), 4K UHD (3840ร2160), and 8K (7680ร4320). 4:3 was the analog broadcast standard, now used for presentations and retro designs.
Cinema Widescreen Ratios
2.35:1 (CinemaScope) is the iconic widescreen ratio for epic cinematic visuals. 1.85:1 (Vista) is standard for North American cinema. 2.39:1 is used in modern anamorphic filming.
Ultrawide & Gaming Monitors
21:9 "ultrawide" is popular for immersive gaming and multitasking. Key resolutions: UWQHD (3440ร1440) and WFHD (2560ร1080). 32:9 (super ultrawide) provides dual-monitor-equivalent width (5120ร1440) in a single display.
๐ก How to Calculate Aspect Ratios & Handle Rounding
Calculating aspect ratio from pixel dimensions
Divide both width and height by their Greatest Common Divisor (GCD). Example: 1920รท120=16, 1080รท120=9 โ 16:9. The GCD is efficiently computed using the Euclidean algorithm (gcd(a,b) = gcd(b, a%b)). This tool performs this calculation in real-time.
Calculating pixels from aspect ratio
Based on width: Height = Width ร (height ratio รท width ratio). Example: width 1280px at 16:9 โ height = 1280 ร 9 รท 16 = 720px. Based on height: Width = Height ร (width ratio รท height ratio). Decimals are rounded to integers.
