Image Resolution & DPI Converter — Pixels, DPI, Print Size

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Image Resolution / DPI

Pixels • DPI / PPI • Print Size

What do you want to find? ⓘ

Pixels (one side) ⓘ

DPI / PPI ⓘ

Print Length (one side) ⓘ

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Enter values to calculate

How to Use the Image Resolution / DPI Converter

Choose what to find — Print Size, DPI/PPI, or Pixels Needed.
Enter the two known values — the field for what you're solving hides automatically.
Pick your length unit — inches, cm, or mm for the print size.
Read the result — plus pixels, DPI, and print size in both inches and cm.
Check the quality rating — instantly see whether the result is photo-quality, good, draft, or too low for print.

Why Use This DPI Converter

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One Simple Formula

Everything follows inches = pixels ÷ DPI. Solve for any of the three from the other two, instantly.

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Print-Quality Rating

Know before you print: 300+ DPI is photo-quality, 150–300 is good, under 150 risks looking pixelated.

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100% Private

All calculations run in your browser — no upload, no server, nothing sent anywhere.

DPI, PPI & Image Resolution Guide

Image resolution links three things: the number of pixels in an image, the print size, and the pixel density (DPI or PPI). They're tied together by one simple formula: print length (inches) = pixels ÷ DPI. Rearranged, DPI = pixels ÷ inches, and pixels = DPI × inches. PPI (pixels per inch) describes digital images and screens; DPI (dots per inch) describes printers — but for everyday photo work the two numbers are used interchangeably.

The 300 DPI rule: for sharp photo prints viewed up close, aim for 300 DPI. So a 4×6 print needs 1,200 × 1,800 pixels (about 2.2 megapixels), an 8×10 needs 2,400 × 3,000 pixels (7.2 MP), and an 11×14 needs 3,300 × 4,200 pixels (13.9 MP). Large prints viewed from a distance — posters, banners — can drop to 150 DPI or even lower without looking bad, because your eye can't resolve the difference at viewing distance.

Screens are different. Web and screen images are traditionally described as 72 or 96 PPI, but what actually matters on screen is the raw pixel count, not the DPI tag — a 1920×1080 image fills a 1080p screen regardless of its embedded DPI. DPI only becomes physically meaningful when you print. That's why resizing an image's DPI without changing its pixel count changes the print size but not how it looks on a monitor.

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Pixels for Photo Prints (300 DPI)

4×6 in: 1200×1800 (2.2 MP). 5×7: 1500×2100 (3.1 MP). 8×10: 2400×3000 (7.2 MP). 11×14: 3300×4200 (13.9 MP). 16×20: 4800×6000 (28.8 MP).

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Quality by DPI

300+ DPI: photo-quality, close viewing. 200–300: very good. 150–200: acceptable / draft. 72–150: posters viewed at distance. Under 72: visibly pixelated in print.

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Screens & Web

For screens, pixel count rules, not DPI. Web images: just match the display size in pixels. Phone screens are ~400–500 PPI; 4K monitors ~140–160 PPI. Embedded DPI is ignored on screen.

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The Formula

inches = pixels ÷ DPI. DPI = pixels ÷ inches. pixels = DPI × inches. 1 inch = 2.54 cm. To get DPI from a metric size, convert cm to inches first (÷ 2.54).

Formula & Logic

Pixel dimensions and physical print size are linked by resolution in dots per inch, and the relationship explains almost every printing disappointment. An image has a fixed number of pixels; DPI determines how densely they are packed onto paper, and therefore how large the print can be before individual pixels become visible. 300 DPI is the standard for photographic print quality, 150 is acceptable for posters viewed at a distance, and 72 DPI is a legacy screen convention that has no real meaning on modern displays but still appears in software defaults.

Pixels = Print size (inches) × DPIPrint size (inches) = Pixels ÷ DPIMegapixels = (width × height) ÷ 1,000,000Changing DPI without resampling changes print size, not image data

where:

DPI/PPI: dots or pixels per inch — density, not quantity
resampling: actually adding or removing pixels, which changes the file
300 DPI: photographic print standard; 150 acceptable at viewing distance

Assumptions: Upscaling cannot create detail that was never captured — interpolation invents plausible pixels rather than recovering real ones. Viewing distance matters: a billboard at 20 DPI looks sharp from across a street.

Step-by-Step Example: Printing an 8 × 10 Photograph

Find the pixels required for a quality print, then see what the same file gives at 72 DPI.

Print size8 × 10 inches
Target quality300 DPI

Width in pixels: 8 × 300 = 2,400.
Height in pixels: 10 × 300 = 3,000.
Total: 2,400 × 3,000 = 7,200,000 pixels, or 7.2 megapixels.
Now take that same file and set it to 72 DPI without resampling.
Print width becomes 2,400 ÷ 72 = 33.3 inches, height 3,000 ÷ 72 = 41.7 inches.
The image data is identical — only the printed size and quality changed.

Result2,400 × 3,000 pixels (7.2 MP) for an 8 × 10 at 300 DPI

A 12-megapixel phone camera at 4,000 × 3,000 prints 13.3 × 10 inches at 300 DPI — more than enough for most purposes. The common mistake is upscaling a small web image for print, which produces a large blurry file rather than a larger sharp one.

Image Resolution / DPI FAQ

How many pixels do I need for an 8×10 print? ▾

At the photo-quality standard of 300 DPI, an 8×10 inch print needs 8 × 300 = 2,400 pixels on the short side and 10 × 300 = 3,000 pixels on the long side, so 2,400 × 3,000 pixels — about 7.2 megapixels. At a more relaxed 200 DPI you'd need 1,600 × 2,000 (3.2 MP), which still looks good for most prints viewed at normal distance.

What is the difference between DPI and PPI? ▾

PPI (pixels per inch) measures the pixel density of a digital image or screen. DPI (dots per inch) measures the ink dots a printer lays down. In casual use they're treated as the same number, and this tool uses them interchangeably. Technically a printer may use several dots to reproduce one pixel, so its hardware DPI (1200–4800) is higher than the image PPI (often 300) — but for sizing photos, "300 DPI" and "300 PPI" mean the same target.

Does changing DPI improve image quality on screen? ▾

No. On a screen, only the pixel count matters — a 2000×3000 image looks identical whether its embedded DPI tag says 72 or 300. DPI only affects physical print size: at 300 DPI that image prints at about 6.7×10 inches, while at 150 DPI the same pixels print at 13.3×20 inches but with half the density. Changing the DPI value without resampling just changes the print size, not the on-screen appearance.

What DPI is good enough for a poster? ▾

Large posters are viewed from a distance, so they don't need 300 DPI. 150 DPI is typically fine for posters viewed from a few feet away, and 100 DPI or even less works for big banners and billboards seen from across a room or street. The farther the viewing distance, the lower the DPI you can use without anyone noticing — which is why a billboard can be printed at well under 50 DPI.

How do I calculate DPI from pixels and print size? ▾

Divide the pixel dimension by the print length in inches: DPI = pixels ÷ inches. For example, a 3,000-pixel-wide image printed 10 inches wide gives 3,000 ÷ 10 = 300 DPI. If your print size is in centimeters, first convert to inches by dividing by 2.54. Select the "DPI / PPI" mode above and this tool does it for you, including the metric conversion.