Aspect Ratio Calculator
Editing Dimensions — preview reflects exact width × height; ratio is detected from your input.
aspect-ratio: 16 / 9;
Smart Ratio Simplifier
CSS Code Generator
Production-ready CSS for responsive 4:5 containers:
/* Responsive aspect ratio container */ .ratio-box { aspect-ratio: 16 / 9; width: 100%; overflow: hidden; } /* With object-fit for images/video */ .ratio-box img, .ratio-box video { width: 100%; height: 100%; object-fit: cover; }
Live Visual Preview
Preview animates as you calculate
Platform & Device Presets
Common 4:5 Resolutions
| Resolution | Category | Usage |
|---|
4:5 Aspect Ratio Calculator — Complete Creator Guide
The 4:5 aspect ratio is Instagram's recommended portrait post format. It occupies more vertical screen space than square (1:1) or landscape posts, making it the most visible format in a mobile Instagram feed. Fashion photographers, lifestyle bloggers, and e-commerce brands prefer 4:5 for maximum visual impact.
Instagram introduced support for portrait posts in 2015, allowing content taller than square. The maximum portrait ratio Instagram accepts is 4:5 (1080×1350) — anything taller is automatically cropped. This was a strategic decision: taller posts dominate the scroll-feed, reducing how many competitor posts appear on screen. Brands that switched from 1:1 to 4:5 consistently report 10–25% higher engagement rates.
Common Uses
Instagram portrait posts, Facebook portrait posts, Pinterest pins, e-commerce product listings, fashion photography, editorial lifestyle photography.
Supported Platforms
Safe Zone Guide
Pro Creator Tip
Instagram's recommended size for 4:5 portrait posts is 1080×1350 px. This format takes up 80% more vertical space than a square post in the feed, dramatically increasing visibility and engagement on mobile.
CSS Aspect Ratio
aspect-ratio: 4 / 5; width: 100%; height: auto;
Apply this CSS to any element to lock it to the 4:5 ratio. Supported in Chrome 88+, Firefox 89+, Safari 15+, and Edge 88+.
4:5 vs Other Ratios
Best 4:5 Resolutions & Use Cases
| Resolution | Format | Best For | Copy |
|---|---|---|---|
| 1080×1350 | Instagram Portrait | Instagram recommended portrait | Copy |
| 1080×1350 | Facebook Portrait | Facebook portrait post | Copy |
| 800×1000 | Standard 4:5 | General portrait format | Copy |
| 1440×1800 | Hi-Res Portrait | Retina exports | Copy |
| 1000×1250 | Pinterest 4:5 | Pinterest tall pin | Copy |
| 400×500 | Thumbnail 4:5 | Preview thumbnails | Copy |
How to Use the 4:5 Calculator
Frequently Asked Questions — 4:5
Explore Related Aspect Ratios
What Is an Aspect Ratio? Complete Guide for Creators in 2026
An aspect ratio is the proportional relationship between the width and height of an image, video, or display. It's expressed as two numbers separated by a colon — for example, 16:9 means the width is 16 units and the height is 9 units. The actual pixel dimensions can vary infinitely, but the proportion stays constant.
Why Aspect Ratios Matter for Content Creators
Choosing the wrong aspect ratio is one of the most common mistakes in digital content creation. Upload a 16:9 video to TikTok and it shrinks into a tiny rectangle surrounded by black bars. Post a 3:2 photo to Instagram expecting a natural crop and you'll be surprised by what gets cut. Understanding aspect ratios lets you shoot, edit, and export content that looks exactly right on every platform — and understanding how to convert between them is what separates amateur and professional output.
Platform Aspect Ratio Quick Reference
| Platform | Ratio | Optimal Resolution | Use Case |
|---|---|---|---|
| YouTube | 16:9 | 1920×1080 / 3840×2160 | Videos & thumbnails |
| TikTok | 9:16 | 1080×1920 | Vertical video |
| Instagram Reels | 9:16 | 1080×1920 | Vertical video |
| Instagram Post | 1:1 / 4:5 | 1080×1080 / 1080×1350 | Feed posts |
| DSLR Camera | 3:2 | Varies (6000×4000 typical) | Photography |
| iPad | 4:3 | 2048×1536 / 2360×1640 | Tablets |
| Ultrawide Monitor | 21:9 | 3440×1440 | Gaming & design |
| Super Ultrawide | 32:9 | 5120×1440 | Samsung Odyssey |
How to Calculate Aspect Ratio from Pixels
To find the aspect ratio of any resolution, divide both width and height by their Greatest Common Divisor (GCD). For 1920×1080: the GCD is 120. Divide: 1920÷120=16, 1080÷120=9. Result: 16:9. Our Smart Ratio Simplifier above does this calculation instantly for any resolution you enter.
Aspect Ratio in Responsive Web Design
Modern CSS makes it simple to lock elements to a specific aspect ratio using the aspect-ratio property. This ensures videos, images, and UI containers maintain their proportions at all screen widths. Previously developers used the "padding-top percentage hack," but the CSS aspect-ratio property (supported since 2021 in all major browsers) is the clean, modern approach.
Related Tools on FastSaveMedia
- Video Cropper — Crop videos to exact aspect ratios for TikTok, Instagram, and YouTube
- Social Media Resizer — Resize images to exact platform dimensions instantly
- Safe Zone Checker — Preview UI overlaps on TikTok, Reels, and Shorts
Aspect Ratio Calculator Hub
Jump to any ratio for platform-specific guides, resolutions, and export tips.