AspectCalc
Free aspect ratio calculator. Turn any width and height into a simplified ratio, resize to a target ratio, preview the shape live and copy the CSS. No sign-up required.
Free aspect ratio calculator. Turn any width and height into a simplified ratio, resize to a target ratio, preview the shape live and copy the CSS. No sign-up required.
This page is designed to help you find out whether AspectCalc is good and if it is the right choice for you.
AspectCalc turns any width and height into a simplified ratio, resizes to a target ratio, and shows a live visual preview as you type — so you see the actual shape before you commit to it, not just the numbers.
How it works
aspect-ratio property for the exact ratio shownWhy it exists
Built this because I kept doing the same math manually every time a video or image needed to be resized for a different platform — Instagram wants 4:5, TikTok wants 9:16, YouTube thumbnails want 16:9, and none of them match by default. Rather than opening a generic calculator and doing the division by hand, this does both directions of the problem (finding a ratio, and resizing to one) in one place, with the visual preview to catch mistakes before export.
No sign-up, no ads, everything runs client-side in the browser.
Listed in
Ratio Calculator
Converts any width and height into a simplified aspect ratio and decimal value
Resize by Ratio
Calculates the missing width or height for any target aspect ratio
Live Visual Preview
Shows the rectangle shape update in real time as you type
Closest Standard Ratio Match
Flags how close a non-standard resolution is to the nearest common ratio like 16:9 or 4:3
CSS Export
One-click copy of the CSS aspect-ratio property for the calculated ratio
No Sign-Up Required
Fully usable without creating an account, runs entirely in the browser
HTML, CSS, JavaScript
Most aspect ratio calculators only do simple division and stop there. AspectCalc adds a live preview so you can visually confirm a crop or resize before committing, a "closest standard ratio" check for imprecise resolutions, and a one-click CSS export — all with no sign-up and no ads.
It handles both directions of the aspect ratio problem in one tool — calculating the ratio from a given size, and resizing to a target ratio — with a live visual preview that shows the actual shape as you type, not just numbers. It also flags how close a non-standard resolution is to the nearest common ratio (useful for catching things like a "16:9" screen that's actually slightly off), and lets you copy the CSS aspect-ratio property in one click.
Content creators, video editors and social media managers who need to resize content across platforms with different aspect ratios (Instagram, TikTok, YouTube), along with designers and front-end developers who need exact ratio math for layouts and CSS.
Built out of a recurring personal annoyance — manually calculating aspect ratios every time a video or image export needed to fit a different platform's required shape. Rather than doing the division by hand each time, AspectCalc turned that into a tool that handles both directions of the calculation with a live preview.
We have collected here some useful links to help you find out if AspectCalc is good.
Check the traffic stats of AspectCalc on SimilarWeb. The key metrics to look for are: monthly visits, average visit duration, pages per visit, and traffic by country. Moreoever, check the traffic sources. For example "Direct" traffic is a good sign.
Check the "Domain Rating" of AspectCalc on Ahrefs. The domain rating is a measure of the strength of a website's backlink profile on a scale from 0 to 100. It shows the strength of AspectCalc's backlink profile compared to the other websites. In most cases a domain rating of 60+ is considered good and 70+ is considered very good.
Check the "Domain Authority" of AspectCalc on MOZ. A website's domain authority (DA) is a search engine ranking score that predicts how well a website will rank on search engine result pages (SERPs). It is based on a 100-point logarithmic scale, with higher scores corresponding to a greater likelihood of ranking. This is another useful metric to check if a website is good.
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