Free visual calculator

Aspect ratio crop calculator

Find the largest crop that fits a target aspect ratio. See the final crop dimensions, pixels removed from each edge and percentage of image or video area lost.

Source and target

Calculated locally
Left / topRight / bottom
Move the crop window toward the part of the frame you want to keep.
Largest matching crop
608 × 1080 px
Source 16:9Target 9:16Kept 31.67%Lost 68.33%
Crop axisHorizontal
Total removed1,312 px
Start edge656 px left
End edge656 px right
Output is rounded to whole pixels, so the final ratio may differ by a tiny fraction.

How the aspect ratio crop calculator works

The calculator finds the largest rectangle with your target ratio that fits entirely inside the source dimensions. It never enlarges or stretches the source. If the source is wider than the target, pixels are removed from the left and right. If the source is taller, pixels are removed from the top and bottom.

kept area % = (crop width × crop height) ÷ (source width × source height) × 100

Crop loss is 100% minus the retained area. Because files use whole pixels, the calculated crop width or height is rounded to the nearest pixel.

Example: crop 16:9 to 9:16

A 1920×1080 landscape source converted to a centered 9:16 frame produces a 608×1080 crop after whole-pixel rounding. It removes 1,312 horizontal pixels—656 from the left and 656 from the right—and retains about 31.67% of the original area.

This large loss is why vertical versions often need manual reframing rather than an automatic center crop.

Crop vs resize vs padding

Crop

Changes the shape by removing source pixels. It fills the target frame without distortion.

Proportional resize

Changes pixel dimensions but keeps the original shape. Use the aspect ratio converter.

Padding or letterboxing

Keeps the full source and adds empty space when the source and target shapes differ.

How to crop with less visual damage

Protect the subject

Move the alignment toward faces, products or important action instead of assuming the center is best.

Leave working space

Capture or design with extra room around key content when multiple formats are planned.

Check text and overlays

Keep titles away from edges and preview the final platform interface before publishing.

Frequently asked questions

Does changing aspect ratio always require cropping?

No. You can preserve the complete source by adding padding, or distort it by stretching. Cropping is required only when you want a different-shaped frame filled without distortion or empty space.

Why does the result differ slightly from the exact target ratio?

Pixel dimensions must be whole numbers. When the ideal width or height is a fraction, the calculator rounds to the nearest pixel, which can cause a very small ratio difference.

Does this calculator upload my image or video?

No upload is needed. Enter only the source dimensions; all calculations and the preview run in your browser.

Is area loss the same as width or height loss?

Not always. Area compares total source pixels with total crop pixels. The tool also shows the exact pixels removed along the affected axis.

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