Aspect Ratio Calculator
Find the aspect ratio from an image or video width and height, or calculate the missing pixel size from a ratio like 16:9 and one known side. Common resolutions such as 1920 x 1080 and 3840 x 2160 are available in the quick charts.
This tool has been used … times.
1
Get Aspect Ratio from Size
Enter width and height to see the simplest ratio and the closest common format.
px
x
px
Aspect Ratio
16 : 9
Landscape · 16:9 (widescreen)
1920 x 1080
About 1.778 : 1 landscape size.
2
Calculate Size from Ratio and One Side
Match a ratio like 16:9 by setting either width or height.
:
Height
1080 px
3
Pick a Common Size
Choose a platform preset to fill size and ratio instantly.
4
16:9 & 9:16 Pixel Size Chart
Typical resolutions for each ratio. Tap a size to load it into the calculator above.
16 : 9Landscape video · YouTube · PC monitors
9 : 16Vertical video · Stories · Reels
4 : 3Standard screens · Presentations
1 : 1Square SNS posts · Icons
4 : 5Instagram portrait posts
3 : 2Digital cameras · Photo prints
Both Full HD (1920 x 1080) and 4K (3840 x 2160) reduce to 16:9. Ultrawide monitors labeled 2560 x 1080 are often called “21:9,” but the exact reduced ratio is 64:27.
Aspect Ratio Quick Reference
16 : 9Video · YouTube · Landscape banners
4 : 3Standard screens · Presentations
1 : 1Square SNS posts · Icons
4 : 5Instagram portrait posts
9 : 16Vertical video · Stories
3 : 2Digital cameras · Photos
How to Use
- Enter the original width and height to confirm the exact aspect ratio.
- To resize for another format, enter the target ratio and the known side.
- If you already know the platform, pick a preset and use it as-is.
Frequently Asked Questions
- What are the pixel sizes for 16:9?
- Common ones are 1280 x 720 (HD), 1920 x 1080 (Full HD), 2560 x 1440 (WQHD), and 3840 x 2160 (4K). All of them reduce to 16:9. Pick one from the pixel size chart above to load it into the calculator.
- What ratio are Full HD and 4K?
- Both are 16:9. 1920 x 1080 divides by 120, and 3840 x 2160 divides by 240, both landing on 16:9. The resolution differs, but the shape of the frame is the same.
- What size should I use for 9:16 vertical video?
- 1080 x 1920 is the standard. Instagram Stories and Reels, TikTok, and YouTube Shorts all use this as the baseline. For a lighter file, 720 x 1280 is still 9:16.
- What is an aspect ratio?
- It is the width-to-height proportion of an image or video. For example, 16:9 means 16 units wide for every 9 units tall, and it is the common standard for landscape video such as YouTube.
- How do 16:9 and 4:3 differ?
- 16:9 is a widescreen landscape ratio used by modern video and monitors. 4:3 is closer to a square and was common on older TVs and standard monitors.
- What aspect ratio should I use for Instagram?
- Square posts are 1:1, portrait posts are 4:5, and Stories / Reels are 9:16. You can load these instantly from the “Pick a Common Size” presets.
- How do I resize an image while keeping the ratio?
- Decide either the width or the height based on the ratio from this tool, and the other side is calculated automatically. To actually shrink an image file, combine this with an image resize tool.