How to use the aspect ratio calculator
- Pick a ratio preset (or choose Custom and enter your own, like 2.39:1 → 239:100).
- Type the dimension you know — width or height. The other fills in instantly.
- Edit either field any time; the ratio stays locked.
Common resolutions cheat sheet
- 16:9 — 1280×720 (HD) · 1920×1080 (Full HD) · 2560×1440 (QHD) · 3840×2160 (4K)
- 9:16 — 1080×1920 (TikTok, Reels, Shorts, Stories)
- 1:1 — 1080×1080 (Instagram feed)
- 4:5 — 1080×1350 (Instagram portrait)
- 21:9 — 2560×1080 · 3440×1440 (ultrawide monitors)
- 3:2 — 3000×2000 (DSLR photos, many laptop screens)
Frequently asked questions
How do I calculate height from width for 16:9?
Multiply the width by 9 and divide by 16. For 1920 wide: 1920 × 9 ÷ 16 = 1080. This calculator does it instantly for any ratio, in both directions.
What are the standard 16:9 resolutions?
1280×720 (HD), 1920×1080 (Full HD), 2560×1440 (QHD) and 3840×2160 (4K UHD). Vertical video flips it to 9:16 — typically 1080×1920.
Which aspect ratio should I use for social media?
9:16 for TikTok, Reels and Shorts; 1:1 or 4:5 for Instagram feed posts; 16:9 for YouTube; roughly 1.91:1 (1200×630) for link preview images.