DPI / PPI Calculator
Calculate pixel density (PPI) for screens, determine print dimensions from image resolution, or find the resolution needed for a specific print size. Switch between modes below.
Common Device PPI Values
Pixel density varies dramatically across devices. Phones pack the most pixels per inch, while larger monitors spread pixels over more area.
| Device | Resolution | Screen Size | PPI |
|---|---|---|---|
| iPhone 15 Pro | 1179 × 2556 | 6.1" | 460 |
| iPhone 15 Pro Max | 1290 × 2796 | 6.7" | 460 |
| Samsung Galaxy S24 | 1080 × 2340 | 6.2" | 416 |
| Google Pixel 8 | 1080 × 2400 | 6.2" | 428 |
| iPad Pro 12.9" | 2048 × 2732 | 12.9" | 264 |
| iPad Air 11" | 2360 × 1640 | 10.9" | 264 |
| MacBook Air 13" (M2) | 2560 × 1664 | 13.6" | 224 |
| MacBook Pro 16" | 3456 × 2234 | 16.2" | 254 |
| Dell UltraSharp 27" 4K | 3840 × 2160 | 27" | 163 |
| iMac 24" | 4480 × 2520 | 23.5" | 218 |
| Dell 24" FHD | 1920 × 1080 | 23.8" | 93 |
| 27" QHD Monitor | 2560 × 1440 | 27" | 109 |
| 32" 4K Monitor | 3840 × 2160 | 32" | 138 |
| LG OLED 48" TV | 3840 × 2160 | 48" | 92 |
| 65" 4K TV | 3840 × 2160 | 65" | 68 |
DPI vs PPI -- What Is the Difference?
Although DPI and PPI are often used interchangeably, they describe different things:
| Term | Stands For | Applies To | Description |
|---|---|---|---|
| DPI | Dots Per Inch | Printers | The number of ink dots a printer places per inch. Higher DPI means finer detail and smoother gradients in print. |
| PPI | Pixels Per Inch | Screens | The number of pixels per inch on a digital display. Higher PPI means sharper text and images on screen. |
In practice: When preparing images for print, you set the "DPI" in your image editor (which is technically PPI of the image file). When evaluating screen sharpness, you calculate PPI from the display resolution and physical size.
Recommended DPI for Different Uses
| Use Case | Recommended DPI/PPI | Notes |
|---|---|---|
| Web / Screen display | 72 -- 96 | Standard screen resolution; higher PPI screens scale images automatically |
| Email / Social media | 72 -- 150 | Keep file sizes small while maintaining clarity |
| Draft / Proofing prints | 150 | Acceptable for review copies, saves ink and time |
| Standard printing | 200 -- 250 | Good quality for newsletters, flyers, and everyday documents |
| Photo printing | 300 | Industry standard for photographic prints; the sweet spot of quality vs. file size |
| Fine art / Gallery prints | 300 -- 600 | Maximum detail for close-up viewing; used by professional labs |
| Large format posters | 100 -- 150 | Viewed from a distance; lower DPI is acceptable and reduces file size |
| Billboard / Signage | 30 -- 72 | Viewed from far away; very low DPI is sufficient |
The Formulas
PPI from Screen Resolution
PPI = sqrt(width_px^2 + height_px^2) / diagonal_inches
Example: 27" 4K Monitor
Input: 3840 × 2160 pixels, 27" diagonal
- Diagonal pixels = sqrt(3840^2 + 2160^2) = sqrt(14,745,600 + 4,665,600) = sqrt(19,411,200) = 4,406
- PPI = 4,406 / 27 = 163.2 PPI
Print Size from Image Resolution
Print Width = image_width_px / DPI
Print Height = image_height_px / DPI
Example: 24MP Photo at 300 DPI
Input: 6000 × 4000 pixels, 300 DPI
- Print width = 6000 / 300 = 20 inches (50.8 cm)
- Print height = 4000 / 300 = 13.33 inches (33.9 cm)
- Maximum print size: 20 × 13.3 inches
Required Resolution for Print Size
Required Width (px) = print_width_inches × DPI
Required Height (px) = print_height_inches × DPI
Example: 8×10 Photo at 300 DPI
Input: 8 × 10 inches at 300 DPI
- Required width = 8 × 300 = 2,400 pixels
- Required height = 10 × 300 = 3,000 pixels
- Required resolution: 2,400 × 3,000 pixels (7.2 MP)
Frequently Asked Questions
What is the difference between DPI and PPI?
DPI (Dots Per Inch) refers to the density of ink dots a printer can lay down per inch. PPI (Pixels Per Inch) refers to the pixel density of a digital screen or image. While the terms are often used interchangeably in casual conversation, DPI is technically a print/output measurement and PPI is a screen/input measurement. When setting image resolution in software like Photoshop, the "DPI" setting is actually PPI -- it controls how many pixels map to each inch when printed.
What DPI should I use for printing photos?
For high-quality photo prints, 300 DPI is the industry standard. At 300 DPI, individual pixels are indistinguishable to the naked eye at normal viewing distance (about 10-12 inches). For large prints that will be viewed from farther away, you can use lower DPI (150-200) without noticeable quality loss. Draft prints or proofs can use 150 DPI.
Why does my phone have a higher PPI than my monitor?
Phones are viewed at closer distances (8-12 inches) compared to monitors (18-30 inches). To appear equally sharp at closer viewing distances, phones need much higher pixel density. A 460 PPI phone viewed at 10 inches and a 110 PPI monitor viewed at 28 inches can appear similarly sharp to the human eye.
What is Retina display?
"Retina" is Apple's marketing term for displays with pixel density high enough that individual pixels are not discernible at a typical viewing distance. For phones, this means roughly 300+ PPI. For laptops, around 220+ PPI. For desktop monitors viewed from farther away, even 200 PPI can qualify. The key idea is that the pixel density exceeds what the human eye can resolve at the expected viewing distance.
How many megapixels do I need for a specific print size?
Multiply the print dimensions in inches by the DPI, then multiply the width and height pixel values. For example, an 8×10 print at 300 DPI requires 2400×3000 = 7.2 megapixels. A 16×20 poster at 300 DPI requires 4800×6000 = 28.8 megapixels. Use the Required Resolution calculator above to get exact numbers.
Does changing DPI change image quality?
Changing the DPI metadata of an image (without resampling) does not alter the pixel data at all. It only changes how large the image prints. A 3000×2000 image set to 300 DPI prints at 10×6.67 inches. The same image set to 150 DPI prints at 20×13.33 inches -- same pixels, just spread over a larger area. Resampling (adding or removing pixels) does affect quality.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.
Privacy & Limitations
Privacy: This calculator runs entirely in your browser. No data is transmitted or stored anywhere.
Limitations: PPI calculations assume square pixels and an exact diagonal measurement. Actual pixel density may vary slightly due to bezel-to-bezel measurement differences. Print quality depends on many factors beyond DPI, including paper type, ink quality, and viewing distance.
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DPI Calculator FAQ
What is the difference between DPI and PPI?
DPI (Dots Per Inch) refers to the number of ink dots a printer can place in one inch. PPI (Pixels Per Inch) refers to the pixel density of a digital screen. While often used interchangeably, DPI is technically a print term and PPI is a screen term. For digital images, PPI describes how many pixels are packed into each inch of the display.
How do I calculate PPI for my screen?
Use the formula PPI = sqrt(width_pixels^2 + height_pixels^2) / diagonal_inches. For example, a 1920x1080 display at 15.6 inches diagonal has PPI = sqrt(1920^2 + 1080^2) / 15.6 = 2203 / 15.6 = 141.2 PPI.
What DPI should I use for printing?
For high-quality photo printing, use 300 DPI. For standard documents and everyday printing, 150-200 DPI is sufficient. For large format prints viewed from a distance (posters, banners), 72-150 DPI is acceptable. Web images typically use 72-96 PPI.
How do I calculate print size from image resolution?
Divide the image pixel dimensions by the DPI. For example, a 3000x2000 pixel image printed at 300 DPI will be 10x6.67 inches (3000/300 = 10 inches wide, 2000/300 = 6.67 inches tall).
What resolution do I need for a specific print size?
Multiply the desired print size in inches by the DPI. For example, to print an 8x10 inch photo at 300 DPI, you need an image that is 2400x3000 pixels (8x300 = 2400, 10x300 = 3000).
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.