DPI Calculator
Calculate print size from pixels, find required resolution for target size, convert between DPI values
Screen Specifications
Results
Resolution Scaler
Calculate required pixel dimensions when changing DPI. Useful for preparing images for different output sizes.
You have a 4000×3000 pixel image and need to know how large it will print at 300 DPI. Or a client wants a 24×36 inch poster and you need to calculate the minimum pixel dimensions. Or you’re comparing screen specifications and need to convert between PPI values. This calculator handles all three DPI-related calculations.
Why This Tool
DPI calculations are simple math (pixels = inches × DPI) but easy to get wrong when you’re juggling width, height, and multiple DPI values. This tool shows all three relationships — pixels, physical size, and DPI — and updates any value when you change the others. No ads, no signup, runs entirely in your browser.
DPI vs PPI
These terms are often used interchangeably but have distinct meanings:
- DPI (Dots Per Inch): Refers to the physical dots a printer places per inch. Relevant for print output.
- PPI (Pixels Per Inch): Refers to the pixel density of a digital display or image. Relevant for screens.
In practice, when someone says “300 DPI image,” they mean the image has enough pixels to print at 300 pixels per inch.
The Core Formula
Pixels = Physical Size (inches) × DPIRearranged:
- Print size: inches = pixels ÷ DPI
- Required pixels: pixels = inches × DPI
- Effective DPI: DPI = pixels ÷ inches
Standard DPI Values
| DPI | Use Case |
|---|---|
| 72 | Legacy screen resolution (Mac) |
| 96 | Legacy screen resolution (Windows) |
| 150 | Draft-quality print, web images printed |
| 300 | Standard print quality (photos, magazines) |
| 600 | High-quality print (fine art, detailed text) |
| 1200+ | Professional prepress |
Print Size Quick Reference
| Image Size | At 300 DPI | At 150 DPI |
|---|---|---|
| 1200×800 | 4×2.67 in | 8×5.33 in |
| 2400×1600 | 8×5.33 in | 16×10.67 in |
| 3600×2400 | 12×8 in | 24×16 in |
| 4800×3200 | 16×10.67 in | 32×21.33 in |
| 6000×4000 | 20×13.33 in | 40×26.67 in |
Common Questions by Use Case
Printing Photos
For sharp photo prints, use 300 DPI minimum. A 12-megapixel camera (4000×3000 pixels) produces sharp prints up to about 13×10 inches at 300 DPI.
Web Images
Screen DPI doesn’t affect how web images display — browsers use pixel dimensions directly. A 1200px-wide image displays at 1200 CSS pixels regardless of the file’s DPI metadata. DPI metadata only matters when printing.
Large Format Printing
Posters and banners viewed from a distance can use lower DPI (100–150) because the viewer is further away. A billboard at 20 DPI looks fine from 50 feet.
Frequently Asked Questions
Does changing DPI metadata change image quality? No. DPI metadata tells printers how large to print the image. Changing DPI from 72 to 300 in Photoshop without resampling does not add pixels or improve quality — it just changes the print size. Only adding actual pixels (upscaling) changes the resolution.
What DPI should I use for printing? 300 DPI for standard prints (photos, brochures, magazines). 150 DPI is acceptable for large prints viewed from a distance. 600+ DPI for fine art or detailed illustrations with small text.
How do I find an image’s DPI? In most image editors: File → Image Properties or Image → Image Size. In Windows: right-click the file → Properties → Details. Note that DPI metadata is just a suggestion — the actual quality depends on pixel count.
What is the DPI of a phone screen? Modern smartphones have 400–600 PPI (e.g., iPhone 15: 460 PPI, Samsung Galaxy S24: 416 PPI). This high density is why phone screens look sharp compared to desktop monitors (72–120 PPI).
Does this tool work offline? Yes. All calculations are basic arithmetic running in JavaScript in your browser with no server communication.