Aspect Ratio Calculator FAQ
Seven common questions about aspect ratio and resolution.
Frequently asked questions (7)
What aspect ratio is 1920×1080?
It is 16:9. The greatest common divisor of 1920 and 1080 is 120, so dividing both by 120 gives 16:9 (about 1.78:1) — the standard widescreen ratio used for YouTube, monitors, and TVs.
How do I calculate the height for a width at 16:9?
Height = width × 9 ÷ 16. A width of 1280px gives 720px; a width of 1000px gives 562.5px, which rounds to 563px (integer) or 562px (codec-safe even). Lock the ratio and enter only the width to solve it automatically.
What resolution are Instagram Reels and YouTube Shorts?
Reels, Shorts, and TikTok all use a vertical 9:16 ratio at 1080×1920. Instagram feed is 1:1 (1080×1080) or 4:5 portrait (1080×1350). YouTube video is 16:9 (1920×1080) with 1280×720 thumbnails.
Why do video dimensions need to be even numbers?
Codecs like H.264 and H.265 use 4:2:0 chroma subsampling that processes color in 2×2 pixel blocks, so width and height must be even to encode cleanly. When a derived value is odd (563), the even mode snaps it to the nearest even number (562).
How do I resize while keeping the same aspect ratio?
Keep the ratio locked and change only the width or height — the other side recalculates at the same ratio. Changing 16:9 from 1920 wide to 2560 wide, for example, updates the height from 1080 to 1440.
Can it tell me which standard ratio an odd resolution is closest to?
Yes. Enter any width and height and the tool shows both the GCD-reduced ratio and the nearest standard ratio from a list like 16:9, 4:5, and 21:9. Within 0.5% it is marked an exact match, otherwise it is shown as the nearest.
Is this aspect ratio calculator free and private?
It is completely free with no signup. Every calculation runs in your browser, and inputs are stored only in localStorage and the optional ?s= share link. Nothing is sent to a server and no image is ever uploaded.