Aspect ratios
3:4 Aspect Ratio Calculator & Pixel Sizes
Calculate 3:4 portrait dimensions such as 900×1200, compare 4:3 orientation, and solve a missing width or height.
3:4 means three units of width for four units of height. It is a portrait shape. A 900 × 1200 image uses this ratio, whereas 1200 × 900 is landscape 4:3.
Resize With This Ratio — 3:4
Change either side. The other updates proportionally. Results show whole pixels and the exact value before rounding.
Exact height: 1200 px
3:4 dimensions in pixels
There is no single pixel size for a 3:4 frame. These width × height pairs all simplify exactly to 3:4. Choose a size to open it in the full calculator.
| Width (px) | Height (px) | Calculate this size |
|---|---|---|
| 600 | 800 | 600 × 800 |
| 768 | 1024 | 768 × 1024 |
| 900 | 1200 | 900 × 1200 |
| 1080 | 1440 | 1080 × 1440 |
| 1200 | 1600 | 1200 × 1600 |
Use the resizing calculator above for a custom dimension. Changing both sides independently can distort the image; changing one side proportionally preserves the ratio.
How the ratio is calculated
900 ÷ 300 = 3; 1200 ÷ 300 = 4. Dividing both sides by the same value preserves the proportions and gives 3:4. 300 is the greatest common divisor of these dimensions.
Height = width × 4 ÷ 3. Width = height × 3 ÷ 4. These formulas change size without changing shape. They do not crop or pad the source.
Exact 3:4 dimensions in pixels
600 × 800, 768 × 1024, 900 × 1200 and 1200 × 1600 are exact integer examples. At a requested width of 1080, the matching height is 1440. To find height directly, multiply the width by 4 and divide by 3.
Checking orientation before export
A width-to-height ratio is ordered. Swapping the sides changes 3:4 to 4:3. If a print service asks for portrait orientation, check that the longer dimension is entered as height. The same pair in the opposite order describes a landscape frame.
A crop from a 2:3 source
A 1200 × 1800 source cropped to 3:4 becomes 1200 × 1600. A centered crop removes 100 pixels from the top and bottom. Padding instead expands the width to 1350 and retains the original height. Choose based on whether edge details must remain visible.
See what changes when you fit 1200 × 1800 into 3:4
Both diagrams use the same source dimensions. Blue represents source content kept in the result; gray represents discarded edges or added canvas. These are geometric examples, not uploaded photographs.
Choose the result by checking the subject
- Open the source dimensions in the calculator and confirm width comes first.
- Compare the crop with your original image. If a face, caption or important detail crosses the removed region, reposition the crop or choose padding.
- Apply the selected dimensions in your editor. This tool calculates geometry; it does not change or download your file. Fractional sizes need whole-pixel rounding and the final ratio may be approximate.
A diagram cannot decide composition or platform eligibility. Check the exported file in its destination, and avoid stretching the dimensions independently. Read our calculation method and corrections process.
3:4 resizing examples
| Width | Exact height | Rounded height |
|---|---|---|
| 320 px | 426.6667 px | 427 px |
| 640 px | 853.3333 px | 853 px |
| 1080 px | 1440 px | 1440 px |
| 1920 px | 2560 px | 2560 px |
Decimal heights are displayed to four decimal places. Rounding can change the final ratio slightly. For an exact integer result, use dimensions that are whole-number multiples of 3:4.