Use this free aspect ratio calculator to instantly find the ratio of any width and height, or scale dimensions while preserving the original ratio. Essential for video creators, photographers and designers working across platforms with different required aspect ratios.
Common presets
Getting your aspect ratio wrong is one of those small mistakes that makes professional content look amateur. Upload a landscape video to TikTok and you get black bars. Export a thumbnail at the wrong size and it looks blurry or gets cropped. Knowing the correct dimensions before you start saves you from reworking everything at the end.
This calculator works two ways — enter a width and height to find the ratio, or enter a ratio and one dimension to calculate the other. Use it when you're setting up a project, checking before export, or figuring out how to resize existing content for a different platform.
Step 1 — Enter the width and height of your content. Type in the current dimensions of whatever you're working on — your video resolution, your image size, your canvas dimensions. The tool will calculate the exact aspect ratio for you.
Step 2 — Or enter a ratio to calculate target dimensions. If you know you need 16:9 and want to know what that looks like at a given width, enter the ratio and one dimension and the other will be calculated automatically.
Step 3 — Use the output to set up your project correctly. Apply the dimensions in your editing software, design tool or export settings before you start — not after. Resizing content after it's been created at the wrong ratio causes quality loss.
Setting up your project at the wrong ratio and fixing it at export. If your editing timeline is set to 16:9 and you want to post to TikTok (9:16), you can't just rotate the export — your footage will be heavily cropped. Always set up your project at the right ratio from the start.
Confusing resolution with aspect ratio. Aspect ratio is the proportional relationship between width and height (e.g. 16:9). Resolution is the actual pixel count (e.g. 1920x1080). You can have the same aspect ratio at many different resolutions — 1280x720 and 1920x1080 are both 16:9.
Using the wrong ratio for thumbnails. YouTube thumbnails should be 16:9 (1280x720 is the recommended size). If you design a thumbnail at a different ratio, YouTube will crop or letterbox it, and it often looks bad in the sidebar and on mobile.
16:9 for standard videos and thumbnails — that's 1920x1080 (1080p) or at minimum 1280x720 (720p). For YouTube Shorts, use 9:16 (1080x1920) — the same as TikTok and Instagram Reels.
Instagram Reels use 9:16 portrait format — 1080 pixels wide by 1920 pixels tall. For feed posts, square (1:1) and portrait (4:5 at 1080x1350) tend to take up the most screen space in the feed and often perform well.
16:9 can be any resolution as long as the ratio is maintained. Common 16:9 sizes are: 1920x1080 (Full HD), 1280x720 (HD), 2560x1440 (2K), 3840x2160 (4K).
The ratio itself doesn't affect quality — but if you force content into the wrong ratio without proper cropping or scaling, it will look stretched, squished or pixelated. Always match your ratio to the platform's requirement before you start creating.
Aspect ratio is the proportional relationship between a frame's width and height. Uploading content with the wrong ratio results in black bars (letterboxing), stretched images or unwanted cropping that makes your content look unprofessional. Every major platform has a preferred ratio — knowing them prevents avoidable presentation errors.