Aspect Ratio Calculator
Find dimensions for an aspect ratio
🔒 Runs locally · Method · · Disclaimer · Aspect Ratio Calculator
Need to find dimensions for an aspect ratio? Aspect Ratio Calculator answers in seconds. You supply Ratio Width (e.g. 16), Ratio Height (e.g. 9) and Known Width (px) to Aspect Ratio; the answer follows at once. Nothing in Aspect Ratio is a black box. That makes Aspect Ratio handy for quick estimates anywhere. No account is needed for Aspect Ratio. The browser does the arithmetic. Looking for aspect ratio calculator 16:9 4:3 resize or free online aspect ratio calculator? Aspect Ratio covers both. Aspect Ratio is designed for real people. Labels stay plain. Try Aspect Ratio now and keep it handy.
What the defaults give
A 16:9 frame at 1,920 px wide is 1,080 px tall.
The ratio does not scale the number, it fixes the relationship: 1,920 ÷ 16 × 9 = 1,080.
The formula
height = width × (ratio height ÷ ratio width)
1,920 × 9 ÷ 16 = 1,080. Going the other way, multiply by the inverse.
Common ratios and what they are for
16:9 — HD, 4K, most video and monitors
4:3 — older television, many stills cameras
21:9 — ultrawide monitors and cinematic crops
1:1 — square social posts
9:16 — vertical phone video and stories
3:2 — most DSLR and mirrorless sensors at full frame
Worked examples
16:9 at 1,920 wide → 1,080 high
16:9 at 1,280 wide → 720 high
4:3 at 1,600 wide → 1,200 high
1:1 at 1,080 wide → 1,080 high
9:16 at 1,080 wide → 1,920 high
Why ratio matters more than resolution
Two images can have the same pixel count and different shapes. Changing the ratio without changing the width crops or letterboxes the image rather than resizing it, which is why a 16:9 video shown on a 4:3 screen has bars above and below. Preserving the ratio while scaling — the point of this calculation — keeps the picture undistorted; ignoring it is what produces stretched faces in badly resized thumbnails.
Practical notes
- Rounding. Non-integer results must land on a whole number of pixels, so one dimension is usually rounded and the ratio is off by a fraction.
- Subsampling. Video encoders often require even dimensions; an odd height can break encoding.
- Cropping versus padding. Fitting a 16:9 clip into 1:1 either crops the sides or adds bars, and neither is a pure rescale.
- Display aspect ratio. Stored pixels and display shape can differ on older video formats, where non-square pixels are involved.
The ratio fixes the relationship, not the size: 16:9 at 1,920 px wide is 1,080 tall, and the same ratio at half the width is 540 tall. Non-integer results have to land on whole pixels, so a 1,000 px wide 16:9 frame is 562.5 and gets rounded, leaving the ratio a fraction off. Video encoders often require even dimensions, which is why 1,080 rather than 1,081 is the practical answer.
Frequently Asked Questions
What is 1920 × 1080 as a ratio?
16:9. Dividing both by 120 gives 16 and 9, and that ratio defines Full HD and 4K UHD.
How do I find the height for a 16:9 video?
Multiply the width by 9 and divide by 16. At 1,920 px wide that is 1,080 px tall.
Is 4K really 16:9?
UHD 4K at 3,840 × 2,160 is 16:9. Cinema 4K at 4,096 × 2,160 is slightly wider, about 1.90:1.
What ratio should I use for phone video?
9:16 for full-screen vertical playback, which is the same 16:9 rotated. Mixing it with 16:9 footage requires cropping or padding.
Does resizing change the ratio?
Not if you scale both sides by the same factor. Changing only one side is what distorts the image.
Why is my exported video slightly off-ratio?
Because pixel dimensions must be whole numbers. A 1,920 × 1,080 frame at 16:9 is exact, but arbitrary widths usually require rounding.
Uptime / Downtime Calculator and other Tech & Digital tools
Uptime / Downtime Calculator · JSON Formatter · IP Subnet Calculator · PX to REM/EM Converter · Streaming Data Calculator · Ad Revenue Calculator · Tech & Digital Guides