Pixel DPI Calculator
Calculate pixels, DPI, PPI and physical print sizes. Convert between pixels and mm, cm, or inches at any resolution. Essential for designers and photographers.
Quick Presets
Dimensions (Pixels)
Physical Size
Resolution
What DPI Should I Use? The Quick Answer
72 DPI for screen-only graphics, 96 DPI for Windows displays, 150 DPI for web images you want to look sharp on Retina screens, and 300 DPI for any image you plan to print. 600 DPI exists for line art and high-quality archival print but is overkill for most photographic work.
DPI (dots per inch) and PPI (pixels per inch) describe how densely pixels are packed into a physical inch when displayed or printed. A 1920x1080 image displayed at 96 DPI takes up 20 inches by 11.25 inches; the same image printed at 300 DPI is just 6.4 inches by 3.6 inches. The pixel count never changes - only the physical size does. This is why exporting a web graphic at 300 DPI does not make it sharper; it just metadata-tags it for print at a smaller physical size.
Pixel Dimensions for Common Print Sizes
A4 at 300 DPI needs 2480 x 3508 pixels. US Letter at 300 DPI needs 2550 x 3300 pixels. A 4x6 inch photo print needs 1200 x 1800 pixels. If your source image is smaller than these targets, the printer will upscale and the result will look soft. If the image is larger, the printer downsamples and quality is fine.
The maths is simple: pixels = inches × DPI. A 5x7 print at 300 DPI needs 1500 x 2100 pixels. A 16x20 poster at 300 DPI needs 4800 x 6000 pixels (28.8 megapixels - more than most phone cameras produce). For posters larger than A2 you can drop to 200 DPI without visible quality loss because the typical viewing distance is further away. Use the [aspect ratio calculator](/aspect-ratio-calculator) to plan crops before you size for print.
Pixel Requirements by Print Size and Quality
| Print Size | 150 DPI (web/draft) | 300 DPI (photo) | 600 DPI (archival) |
|---|---|---|---|
| 4x6 inch photo | 600 x 900 | 1200 x 1800 | 2400 x 3600 |
| 5x7 inch photo | 750 x 1050 | 1500 x 2100 | 3000 x 4200 |
| 8x10 inch photo | 1200 x 1500 | 2400 x 3000 | 4800 x 6000 |
| A4 (8.27 x 11.69 in) | 1240 x 1754 | 2480 x 3508 | 4960 x 7016 |
| A3 (11.69 x 16.54 in) | 1754 x 2481 | 3508 x 4961 | 7016 x 9922 |
Common DPI Mistakes That Ruin Print Jobs
The classic error is pulling a 1080 x 1080 Instagram image and trying to print it at A4. At 300 DPI that image is just 3.6 inches square - smaller than a postcard. Stretched up to A4, every pixel becomes roughly 6 actual print dots and the result looks like a screenshot of a screenshot. The image needed to be at least 2480 x 2480 to print A4 cleanly.
The other common mistake is the opposite: shooting in 24 megapixels and emailing the full file when a 1500-pixel-wide version would have done. That 24MP raw is 50MB+ as JPEG and chokes the recipient's inbox. For email and web, 1500 to 2400 pixels on the longest edge at 72 to 96 DPI is plenty. Use the [image resizer](/image-resizer) and [image compressor](/image-compressor) to bring file sizes down before sending. The DPI tag on a screen-only image literally does nothing - it is metadata that print software uses, not browsers.
Frequently Asked Questions
What is the difference between DPI and PPI?
Technically DPI (dots per inch) refers to printer dots and PPI (pixels per inch) refers to screen pixels, but in practice the terms are used interchangeably for image resolution. Photoshop labels the field as PPI; print shops and image software usually call it DPI. The number means the same thing: how many image pixels are crammed into one inch of physical output.
Does changing DPI from 72 to 300 improve quality?
No. Changing the DPI metadata field alone does nothing to the actual pixels. It only changes how big the image will print. A 1920 x 1080 image at 72 DPI prints at 26.7 x 15 inches; the same file at 300 DPI prints at 6.4 x 3.6 inches. To genuinely improve quality you need either more pixels (re-shoot, re-render, or AI upscale) or to print smaller.
How many pixels do I need for a sharp A4 print?
2480 x 3508 pixels is the standard for A4 at 300 DPI. If you only have 1240 x 1754 you can still print at 150 DPI and get a perfectly readable result for most uses (newsletters, posters viewed from a distance, draft proofs). Anything below 1000 pixels on the long edge of an A4 print will look visibly fuzzy when held at arm's length.
Why does my Instagram photo look pixelated when printed?
Instagram serves images at 1080 x 1080 maximum. At 300 DPI that prints to 3.6 x 3.6 inches - smaller than a CD case. Anything larger requires upscaling, which is why the print looks soft. To print Instagram-style square photos properly, save the original from your camera roll (likely 3024 x 3024 or larger) before posting, since Instagram heavily compresses what you upload.
What DPI do professional photographers use?
300 DPI is the print industry standard for photo books, magazines, gallery prints up to 16x20, and most fine art applications. Newspapers and budget print runs often drop to 150 to 200 DPI to save on file size and processing time. Large format (4ft+ posters, billboards) deliberately uses 100 to 150 DPI because the viewer is far away and higher resolution is wasted.
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Pixels to Physical Size Converter
Convert pixels to inches, centimetres, or millimetres and back. Enter your DPI to get exact print dimensions. Two-way conversion with a handy reference table.
Screen PPI Calculator
Calculate the pixels per inch of any screen or display. Enter screen size and resolution, or choose from popular device presets. See if your display is Retina-class.
Megapixel Calculator
Convert between megapixels and pixel dimensions. See what resolution your camera shoots at, estimate file sizes, and check print quality at different paper sizes.
Aspect Ratio Calculator
Calculate and convert aspect ratios for images and video. Lock ratios, use platform presets for Instagram, YouTube, TikTok, and more. Shows megapixels and orientation.