Aspect Ratio FAQ
The dimension questions creators search for, answered — each one paired with the calculator or lookup that demonstrates it live.
How do I calculate height from an aspect ratio?
height = width × rh ÷ rw. Example: 1920 wide at 16:9 → 1920 × 9 ÷ 16 = 1080. Width is the mirror: width = height × rw ÷ rh.
What resolution is 16:9?
Any pair where w/h = 16/9: 640×360, 1280×720, 1920×1080, 2560×1440, 3840×2160 — and any multiple of 16 by 9. Use the lookup pages to check a specific size.
Is 21:9 really 21:9?
Marketing rounds. True panels are 64:27 (2560×1080) or 43:18 (3440×1440) — the calculator simplifies whatever you enter, so enter the real pixels.
What size is a YouTube thumbnail?
1280×720 (16:9), under 2MB, JPG/PNG. Shorts use 1080×1920 vertical (9:16) instead. See the 1280×720 and 1080×1920 lookup pages.
How do I keep aspect ratio in CSS?
aspect-ratio: 16 / 9 on the element; plus the classic padding-top: 56.25% wrapper for very old browsers. Pair with object-fit: cover or contain.
What aspect ratio is 1920×1080?
16:9 (dec. 1.777:1). 1280×720 and 3840×2160 are the same ratio — all divide by GCD 120 or 240 to 16:9.
What about portrait ratios?
Flip the pair: 9:16, 4:5, 2:3 and 1:2 are the portrait partners of 16:9, 5:4, 3:2 and 2:1. The solver handles portrait and landscape identically.
Does the calculator work offline?
Yes — once loaded, all math runs locally in JavaScript. Nothing you type leaves your browser. URL sharing encodes only the numbers.
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