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Image Aspect Ratio Calculator
Read an image’s aspect ratio and calculate the matching height for a new width. Keep proportions before you resize.
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Maximum 20 MB per image
The matching height is calculated. This page does not resize the file.
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A 16:9 image and a 9:16 image have very different orientations. Keep the width:height order consistent.
Quick steps
How to calculate an image’s aspect ratio
Enter the new width
Use the width in pixels that your layout needs, then click Calculate ratio.
Read the matching height
Use the suggested dimensions in Image Resizer to export a new copy.
A few useful details
Work out the matching height before resizing
Aspect ratio is simply the shape of an image. A 1,200 × 800 px picture has a 3:2 ratio. A 600 × 600 px picture is 1:1, or square. The ratio does not tell you how many KB the file uses.
Choose a photo and enter the width you want to use. The calculator gives you the height that keeps the same proportions. You can then enter those dimensions in Image Resizer without guessing.
If a platform needs a different shape, crop the image rather than stretching it. A wide 16:9 banner and a tall 9:16 story use the same numbers in the opposite order, but they are very different frames.
A couple of things to check
A 16:9 image and a 9:16 image have very different orientations. Keep the width:height order consistent.
The calculated height is rounded to a whole pixel. Small differences are normal when the exact result is a fraction.
Use the ratio to keep an image in proportion
Read the ratio in width:height order
The order matters. A 16:9 picture is wide, while 9:16 is tall. They are not two names for the same frame. If you are preparing artwork for a specific space, check whether the destination describes the dimensions as width × height before copying its numbers.
Calculate first, then make the new image
This page helps you work out the matching dimension. After choosing a new width, read the calculated height and use both values in Image Resizer. The calculator itself does not create a smaller file or download a resized picture.
A different shape needs a cropping decision
If your source is 3:2 but the placement is 1:1, keeping the whole image and forcing a square will distort it. Decide which part to keep in Crop Image, then resize the square result. A ratio calculation cannot choose the right crop for your subject.
A one-pixel difference is often rounding
Matching height is calculated from the original proportions and rounded to a whole pixel. At some widths, an exact mathematical result would contain a fraction. Use the rounded value for an image file, then inspect the final output if a destination checks dimensions strictly.
| Pixel dimensions | Simplified ratio | Shape |
|---|---|---|
| 1,200 × 800 | 3:2 | Landscape |
| 1,920 × 1,080 | 16:9 | Widescreen |
| 600 × 600 | 1:1 | Square |
| 900 × 1,600 | 9:16 | Portrait |
Visual examples
Understand the shape of your image
Calculated proportions for sample images. This calculator reports ratios and dimensions; it does not export a resized image.
Input![Landscape: 16:9 — Input]()
Measured![Landscape: 16:9 — Measured]()
EXAMPLE 01
Landscape: 16:9
An 800 × 450 image simplifies to 16:9. Keep that proportion when calculating another width or height.
Calculated proportions for sample images. This calculator reports ratios and dimensions; it does not export a resized image.
Input![Square: 1:1 — Input]()
Measured![Square: 1:1 — Measured]()
EXAMPLE 02
Square: 1:1
A 720 × 720 image has a 1:1 ratio. Equal width and height produce a square.
Calculated proportions for sample images. This calculator reports ratios and dimensions; it does not export a resized image.
Input![Portrait: 4:5 — Input]()
Measured![Portrait: 4:5 — Measured]()
EXAMPLE 03
Portrait: 4:5
A 480 × 600 image simplifies to 4:5. Changing the ratio requires cropping or padding rather than proportional resizing.
Calculated proportions for sample images. This calculator reports ratios and dimensions; it does not export a resized image.
Frequently asked questions
Why do I get a ratio such as 347:251?
The calculator simplifies the actual pixel dimensions. An irregular crop may not reduce to a familiar ratio such as 4:3.
Will it download a resized image?
No. It calculates the dimensions only. Use Image Resizer to create a copy at the width and height shown.
Why is the calculated height rounded?
An image needs whole pixels. If the exact calculation gives a fraction, the height is rounded to the nearest pixel.
Can images with different resolutions have the same ratio?
Yes. Both 1,920 × 1,080 and 1,280 × 720 are 16:9. They share a shape, not the same number of pixels.
Can a ratio tell me how many KB the picture will use?
No. Content, format, dimensions and compression all affect file size. Use the KB tools after the shape and dimensions are right.
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