Calculated result
Results update while you type and after submission.
Common 3:4 presets
Visual preview
The rectangle changes with the selected orientation and calculated dimensions.
Entered versus target shape
This comparison helps identify cropping, padding, or resizing needs.
Formula used
A 3:4 ratio means every three width units correspond to four height units. The same relationship works for pixels, inches, centimeters, and other units. Landscape mode reverses the relationship to 4:3.
How to use this calculator
- Select the calculation mode that matches your task.
- Choose portrait 3:4 or landscape 4:3 orientation.
- Enter the available dimensions, scaling amount, limits, and DPI.
- Select a rounding method and preferred crop or resize behavior.
- Review the calculated dimensions, print size, ratio difference, and correction guidance.
- Copy, print, share, or export the result as CSV or PDF.
Example dimensions
| Width | Height | Orientation | Approximate megapixels |
|---|---|---|---|
| 300 px | 400 px | Portrait | 0.12 MP |
| 600 px | 800 px | Portrait | 0.48 MP |
| 900 px | 1200 px | Portrait | 1.08 MP |
| 1200 px | 1600 px | Portrait | 1.92 MP |
| 1600 px | 1200 px | Landscape | 1.92 MP |
Understanding 3:4 dimensions
The 3:4 aspect ratio is common in portrait photography, printed photographs, profile images, posters, and product listings. It describes shape rather than physical size, so 300 × 400 pixels and 3000 × 4000 pixels share the same ratio. Larger dimensions normally provide more detail, but file quality also depends on compression and the original image.
When an existing image does not match 3:4, you can crop content, expand the canvas, or resize it. Cropping removes material from one pair of edges. Canvas expansion adds empty space, while stretching forces the image into shape and may create visible distortion.
DPI and PPI matter when pixels become printed measurements. A 900 × 1200 pixel image at 300 PPI prints at approximately 3 × 4 inches. The same image at 150 PPI prints larger, but the lower pixel density may reduce sharpness at close viewing distances.
Rounding controls are helpful when software requires whole, even, or block-aligned dimensions. Video tools and image encoders may prefer multiples of two, four, eight, or sixteen. Always check the final ratio after rounding because aggressive rounding can introduce a small difference.
Frequently asked questions
What does a 3:4 aspect ratio mean?
It means the width contains three equal parts while the height contains four equal parts.
Is 3:4 the same as 4:3?
They use the same numbers, but 3:4 is normally portrait and 4:3 is normally landscape.
What is the height for a 900 pixel width?
For portrait 3:4, the exact height is 1200 pixels.
What is the width for a 1600 pixel height?
For portrait 3:4, the exact width is 1200 pixels.
Can I use inches or centimeters?
Yes. Aspect ratios are unitless, so any consistent unit can be used.
Why does rounding slightly change the ratio?
The exact proportional result may be fractional, while image dimensions often require whole numbers.
Should I crop or stretch an image?
Cropping usually preserves natural proportions. Stretching may distort people, text, and objects.
How does DPI affect the result?
DPI converts pixel dimensions into an estimated physical print size.
What does nearest multiple of sixteen do?
It adjusts each calculated dimension to the closest value divisible by sixteen.
Can the calculator compare an existing image?
Yes. Check mode reports the actual ratio, difference, and corrected dimensions.
Are print results exact?
They are mathematical estimates. Printers, margins, scaling, and driver settings can change the final output.
Important note
This calculator provides proportional and print-size estimates. Confirm final dimensions inside your image editor, publishing platform, or printer settings before production.