Aspect Ratio Calculator — Scale Dimensions Proportionally
Find a dimension's aspect ratio and scale it proportionally — enter a new width or height and get the matching dimension instantly.
Last reviewed 2026-10-19. Rates change — verify against the official sources linked below before relying on these figures.
What this is based on
- Ratio is simplified by GCD — 1920×1080 shows 16:9, 1440×900 shows 16:10.
- Scaling rounds to whole pixels — 1280×720.4 becomes 720 (the fraction doesn't exist on screens).
The ratios worth memorizing
16:9 — YouTube, most monitors, TV. 9:16 — Shorts/Reels/TikTok. 1:1 — Instagram feed, avatars. 4:3 — old TV, iPad, slides. 3:2 — DSLR photos, Surface screens. 21:9 — ultrawide cinema. 16:10 — MacBooks and productivity laptops.
When a spec says 'upload a 1200×630 image', it's really saying 1.91:1 — OG images and link previews almost always want that wide format.
Cropping vs letterboxing
When the source and target ratios differ you have two options: crop (fill the frame, lose content at the edges) or letterbox (fit the whole image, add bars). For OG images and thumbnails, crop center-safe with your subject in the middle third — faces and logos near edges get guillotined by platform cropping.
Frequently asked questions
- What is the aspect ratio of 1920×1080?
- 16:9 — divide both by their GCD (120): 16 and 9. Same ratio covers 1280×720, 2560×1440 and 3840×2160 (4K).
- How do I resize an image without distortion?
- Keep the ratio: new height = new width × (original height ÷ original width). This calculator does it — enter the source size and a target width or height.
- What aspect ratio is 1200×630?
- Roughly 1.91:1 — the standard Open Graph/social preview image size.
- Is 4K always 16:9?
- Consumer '4K' (3840×2160) is 16:9. Cinema DCI 4K (4096×2160) is slightly wider (~1.9:1) — different standards, same marketing name.
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