Formula Used
Horizontal DPI = pixel width / physical width in inches.
Vertical DPI = pixel height / physical height in inches.
Diagonal DPI = √(pixel width² + pixel height²) / physical diagonal in inches.
Pixel pitch = 25.4 / DPI. The result is millimeters per pixel.
Target print size = pixels / target DPI for each side.
How to Use This Calculator
- Enter the resolution width and height in pixels.
- Select the mode that matches your known physical measurement.
- Enter width, height, diagonal, or one fixed side.
- Choose inches, centimeters, or millimeters as the size unit.
- Add a target density if you want estimated print dimensions.
- Press Calculate, then review the result above the form.
- Use CSV or PDF buttons to save the same calculation.
Example Data Table
| Use Case |
Resolution |
Physical Size |
Estimated Density |
| Laptop display |
1920 × 1080 px |
15.6 in diagonal |
141.2 DPI |
| Photo print |
3000 × 2400 px |
10 × 8 in |
300 DPI |
| Large poster |
7200 × 4800 px |
36 × 24 in |
200 DPI |
DPI From Resolution Basics
DPI describes how many dots fit inside one physical inch. In display work, the same idea is often called PPI. The calculator treats both as linear pixel density. It links resolution with real width, height, or diagonal size. This matters because a 1920 by 1080 image can look sharp on a phone, yet soft on a large poster.
Why Physical Size Matters
Resolution alone does not define sharpness. Pixel count tells how much digital detail exists. Physical size tells how far that detail is spread. Divide pixels by inches, and you get density. Higher density means smaller pixels. Smaller pixels usually give cleaner edges, smoother text, and finer print detail. Lower density can still work for distant viewing, signage, drafts, or large screens.
Screen And Print Use
For screens, diagonal density is common. It uses the diagonal pixel count and diagonal size. This gives one balanced density value for the panel. For printing, horizontal and vertical density are important. A print may be stretched if width and height densities do not match. The tool reports both values, so you can catch distortion before exporting artwork.
Pixel Pitch And Viewing Distance
Pixel pitch is the physical space used by one pixel. It is shown in millimeters. A small pitch means dense pixels. Viewing distance changes what the eye can notice. A lower density display can seem sharp when viewed from far away. A high density print is useful when the viewer is close. The pixels per degree estimate helps compare density against viewing distance.
Practical Workflow
Start with the resolution. Add physical width and height when both are known. Use diagonal mode when checking monitors, tablets, or phones. Use width only or height only when planning a print size from one fixed edge. Enter a target density to estimate safe print dimensions. Then compare calculated density, pitch, megapixels, and aspect ratio.
Good Density Choices
There is no single perfect DPI. Small reading material often needs high density. Posters may need less because they are viewed farther away. Web graphics depend on layout size and screen scaling. Use this calculator as a planning guide. Always test prints, proof artwork, and follow device or printer specifications when accuracy matters.
FAQs
What does DPI mean in this calculator?
DPI means dots per inch. For digital screens, it is often called PPI. This tool uses it as pixel density, which compares pixel resolution with real physical size.
Can I use diagonal size only?
Yes. Choose diagonal mode. Enter pixel width, pixel height, and physical diagonal. The tool calculates diagonal density and estimates matching width and height.
Why are horizontal and vertical values different?
They differ when the entered physical width and height do not match the pixel aspect ratio. Large mismatch may mean stretching, wrong dimensions, or non-square pixels.
Is DPI the same as PPI?
They are commonly mixed. DPI usually describes print dots. PPI describes screen pixels. For resolution and physical size math, the calculation is similar.
What is pixel pitch?
Pixel pitch is the physical size of one pixel. The calculator reports it in millimeters. Smaller pitch means pixels are packed more closely.
What DPI should I use for printing?
Many close-viewed prints use 300 DPI. Posters and distant signs can use less. Always follow your printer, publisher, or production requirements.
Why enter viewing distance?
Viewing distance helps estimate pixels per degree. It shows how dense the image appears from where a viewer is likely to stand or sit.
Can I export the result?
Yes. After entering values, click the CSV or PDF button. The file contains the same result fields shown above the form.