SMART IMAGE TOOLS IMAGE CALCULATOR
Find the ratio. Choose one new side. Keep the proportions.
START WITH YOUR NUMBERS
LIVE RESULT
1,280 × 720pixels · proportional dimensions
Both dimensions fit whole pixels exactly.
METHOD & EXAMPLES
An aspect ratio compares width with height. Dividing both by their greatest common divisor gives the simplified ratio. Scaling both sides by the same factor preserves that shape.
new height = new width × original height ÷ original widthWorked example1920 × 1080 simplifies to 16:9. At a width of 1280 pixels, the proportional height is 720 pixels.
Image dimensions must be whole pixels, so a calculated side is rounded to the nearest pixel and never below one. The result tells you when rounding was needed. To turn a landscape image into a square or portrait, use cropping or a fitted canvas; proportional resizing alone cannot change its shape.
A PRACTICAL EXAMPLE
Calculate a proportional dimension before resizing.
Changing dimensions is separate from changing file size. Ratio calculations do not predict encoded bytes or remove pixels from an image.
Examples illustrate specific inputs and settings. Actual output size and appearance depend on your file and browser. Practice images are synthetic; they do not contain personal data.
GOOD TO KNOW
Divide the width and height by their greatest common divisor. For 1920 × 1080, that divisor is 120, producing 16:9. Enter your dimensions to calculate it automatically.
Multiply the new width by the original height, then divide by the original width. For a 16:9 image at 1280 pixels wide, the height is 720 pixels.
This calculator plans the dimensions. Open Resize Image to apply them to a file, or use Crop Image to change the shape.
Only the width, height, target dimension and calculation mode. No image or filename is included. Anyone with the link can see those numeric settings.