Aspect Ratio Calculator — Resize Images Without Distortion
Updated October 2026 · 4 min read
Quick start: Open the free Aspect Ratio Calculator — enter the original dimensions and target width or height to get the correct size instantly.
Aspect ratio is the proportional relationship between an image's width and its height. Maintaining it when resizing prevents stretching and squashing. A 1920×1080 image has a 16:9 ratio — resizing to 1280×720 keeps that ratio; resizing to 1280×800 distorts it.
The Formula
New height = (Original height ÷ Original width) × New width
New width = (Original width ÷ Original height) × New height
Example: 1920×1080 → resize to 800px wide: height = (1080 ÷ 1920) × 800 = 450px
Common Aspect Ratios for Web & Social
| Ratio | Common use | Example dimensions |
|---|---|---|
| 16:9 | YouTube thumbnails, HD video, desktop banners | 1920×1080, 1280×720 |
| 1:1 | Instagram posts, profile photos | 1080×1080 |
| 4:5 | Instagram portrait posts | 1080×1350 |
| 9:16 | Instagram/TikTok Reels, Stories | 1080×1920 |
| 1.91:1 | Facebook/LinkedIn link previews | 1200×628 |
| 4:3 | Standard video, older monitors | 1024×768 |
Letterboxing vs Cropping
When converting between ratios (e.g. a 16:9 photo for a 1:1 Instagram post), you must either crop (cut off part of the image) or letterbox (add black/white bars to fill the space). Neither option preserves the full original — choose based on whether losing the edges or gaining blank space is more acceptable for your content.
Calculate New Image Dimensions Instantly
Enter original width and height, then set a new width or height — get the correct proportional size in one click.
Open Free Aspect Ratio Calculator →