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.
Use this tool when the decision is how much of the source to cut away. The preview represents the frame geometry, not the subject in your photo or video. The retained percentage measures source area, not perceived image quality. It does not crop or export a file.
Still deciding whether to crop at all? Compare an expanded canvas with a centered crop in the aspect ratio converter, or calculate padding for a fixed output frame with the black bar calculator.
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) × 100Crop loss is 100% minus the retained area. Because files use whole pixels, the calculated crop width or height is rounded to the nearest pixel.
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.
Changes the shape by removing source pixels. It fills the target frame without distortion.
Changes pixel dimensions but keeps the original shape. Use the missing-dimension calculator for a new proportional size.
Keeps the full source and adds empty space when the source and target shapes differ.
Example source: 4000 × 3000 pixels. Required output: 1200 × 630 pixels for a specified website card. The target ratio is 40:21; these dimensions are an example brief, not a platform rule.
If essential content would be removed: choose a different source, redesign the composition, or fit the full image with padding. Moving the crop changes which pixels are lost, not how much area the same-sized crop retains. For social placements, check overlays separately with the safe-zone checker.
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.
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.
No upload is needed. Enter only the source dimensions; all calculations and the preview run in your browser.
Not always. Area compares total source pixels with total crop pixels. The tool also shows the exact pixels removed along the affected axis.
Preserve the full frame by adding bars.
Simplify any width and height.
Read an image's ratio locally.
Plan matching video dimensions.
Common widescreen sizes.
Protect key content from social app controls.
Common vertical sizes.