How to Use the Aspect Ratio Calculator
1
Enter Width & Height
Input your original dimensions (e.g. 1920 × 1080).
2
Inspect Aspect Ratio
View the simplified ratio (e.g. 16:9) and decimal multiplier.
3
Calculate Proportional Size
Type a target width in the resize calculator to find the exact proportional height.
4
Use Quick Presets
Click presets for 16:9 (HD), 4:3, 1:1 (Square), 9:16 (Reels/TikTok), or 21:9.
Aspect Ratio Formula
The aspect ratio is the ratio of width to height expressed in lowest terms:
Ratio = (Width / GCD(Width, Height)) : (Height / GCD(Width, Height))
New Height = (New Width × Original Height) / Original Width
Why Choose Our Aspect Ratio Calculator?
Calculates simplified aspect ratios via GCD
Proportional resize dimension calculator
Common presets (16:9, 4:3, 1:1, 9:16, 21:9)
Displays decimal ratio multiplier
Instant real-time math calculation
Pro Tips for Best Results
- 16:9 is standard for YouTube and HDTVs; 9:16 is vertical video standard for TikTok, Shorts, and Instagram Reels.
- 1:1 square is the universal standard for avatars and e-commerce product catalogs.