This aspect ratio calculator turns dimensions in one shared unit into a width-to-height ratio and calculates matching dimensions for resizing or fitting a frame.
Find an aspect ratio or resize without stretching
Enter width first and height . Choose one shared unit for the original dimensions, the new dimension and any target frame. Find the aspect ratio reduces the pair. Resize without stretching calculates a missing dimension from one new dimension. Fit or fill a frame calculates the scaled size and either empty space or clipped overflow. Physical measurements can use centimeters, millimeters or inches without converting them to pixels.
All dimensions use the selected shared unit. The calculator does not mix physical units or calculate print resolution.
Fit inside keeps the whole image and may leave space. Fill frame covers the frame and may crop the image.
Fractions describe the exact dimensions. A separate whole-pixel recommendation can change the requested size to preserve the ratio.
Resize, fit and crop examples
The 1920 × 1080 pixel pair reduces to 16:9. Resizing the same pair to width 1280 gives 1280 × 720 pixels, using scale 2/3.
Fit a 4000 × 3000 image inside a 1000 × 1000 pixel frame. The scaled size is 1000 × 750 pixels. The total vertical padding is 250 pixels, centered between the top and bottom.
Fill frame with the same image gives an exact size of 4000/3 × 1000 pixels and 1000/3 pixels of total horizontal crop. Crop amounts are measured after scaling, in the selected unit. They are not a count of original source-image pixels.
Common ratios and exact sizes
Each pair below uses one shared unit. The ratio is calculated from those dimensions, so portrait and landscape pairs retain their order.
| Dimensions | Shared unit | Width:height |
|---|---|---|
| 1920 × 1080 | px | 16:9 |
| 1080 × 1920 | px | 9:16 |
| 1080 × 1080 | px | 1:1 |
| 1200 × 630 | px | 40:21 |
| 2400 × 1600 | px | 3:2 |
| 4000 × 3000 | px | 4:3 |
| 11 × 14 | in | 11:14 |
| 8 × 10 | in | 4:5 |
| 210 × 297 | mm | 70:99 |
Ratios are computed by the engine from illustrative dimension inputs. MDN supports the width-to-height definition, not these example sizes. These are not platform minimums, recommended upload sizes or print-resolution requirements.
Fit inside versus fill the frame
Enter the original dimensions and the target frame dimensions, then choose the frame treatment. Fit inside uses the smaller of the width and height scale factors, so neither scaled dimension exceeds the frame. The whole image remains visible. Fill frame uses the larger scale factor, so both dimensions cover the frame and any overflow is clipped. Both treatments preserve the original width-to-height ratio.
Padding and crop results are total differences between scaled image and frame dimensions. The details also show the amount on each opposite edge for centered placement. This centering is an explicit assumption; a subject near an edge may need a different crop position. All adjustments use the selected unit after scaling. If the image and frame have equal ratios, neither treatment needs padding or crop.
Fractional pixels, centered crop and square-pixel scope
For the 16:9 ratio and requested width 1000, the exact height is 1125/2 pixels. The nearest permitted whole-pixel pair preserving the ratio is 1008 × 567 pixels. That pair changes the requested width, so it is a recommendation alongside the exact result.
The pixel recommendation rounds to a positive whole-number multiple of the reduced ratio, with halfway cases rounded up and both dimensions bounded by the output cap. If even the smallest such pair exceeds the cap, the calculator keeps the exact resized dimensions and explains why it cannot recommend a whole-pixel pair. Physical units retain exact dimensions without that pixel recommendation.
The calculator performs sizing arithmetic and does not edit, upload or export an image. Pixel calculations assume square pixels; pixel aspect ratio, video display metadata, platform size rules and print resolution require additional information.
Dimensions must be positive plain decimals with at most 6 decimal places and a maximum value of 10000000 for each dimension, using the shared unit. Calculated dimensions are capped at 1000000000000. These are Calculator Campus capacity policies. Exact fractions remain authoritative; optional decimal displays round to 6 places and mark approximations.
Ratio Calculator handles general missing proportions and scaling across several terms. Area Converter compares compatible area units; area ratios alone do not determine a picture’s width and height.
Each dimension input accepts at most 64 characters, another Calculator Campus capacity limit.