Print Size Calculator

PPI vs DPI vs LPI: What's the Difference?

PPI (Pixels Per Inch) refers to the digital image resolution - how many pixels from your photo are squeezed into each inch of the print. This is what photographers work with.

DPI (Dots Per Inch) is a printer specification describing how many ink dots the printer lays down per inch. A printer might use multiple dots to create a single pixel. DPI is often used interchangeably with PPI, but PPI is a more accurate measure of the image resolution, and not of the printer's printing resolution.

LPI (Lines Per Inch) refers to the halftone screen frequency used in commercial offset printing. It measures how many rows of halftone dots are printed per inch. Higher LPI values produce finer detail but require higher resolution images. This is a concept that is used in offset printing, and not in desktop printing.

For photographers: Focus on PPI when planning prints. Higher PPI means more detail and sharper prints, but the required PPI depends on viewing distance.

Image Resolution & Pixel Dimensions

Resolution refers to your image's pixel dimensions (width × height). A 6000×4000 pixel image contains 24 million pixels total.

When you print, these pixels are spread across the physical print dimensions. The PPI is calculated by dividing the pixel dimensions by the print size in inches.

Example: A 6000-pixel-wide image printed at 20 inches wide = 300 PPI (6000÷20=300)

Megapixels Explained

Megapixels (MP) is simply the total number of pixels in your image divided by one million. It's a quick way to describe camera sensor resolution.

A 24MP camera typically produces 6000×4000 pixel images. More megapixels allow larger prints at the same quality level or higher quality at the same print size.

Important: More megapixels isn't always better for every situation, but it gives you more flexibility when printing large.

Print Quality Tiers

Different viewing scenarios require different resolution standards:

• Gallery/Fine Art (300 PPI): Close inspection at 18 inches. Museum-quality prints.
• Standard Photo (240 PPI): Normal viewing at 2 feet. Photo albums, portraits.
• Casual/Family (180 PPI): Everyday viewing at 3 feet. Social sharing, gifts.
• Large Format (120 PPI): Viewed from 6+ feet. Posters, wall art, trade shows.

The larger the intended viewing distance, the lower PPI you need for the same perceived quality.

Print Medium Matters

Different print materials have varying resolution requirements:

• Photo Paper: Smooth surface shows maximum detail. Requires higher PPI for best results.
• Canvas: Textured surface naturally hides slight resolution limitations. Can use ~10% lower PPI.
• Metal Prints: Ultra-sharp surface benefits from maximum resolution. Premium quality standard.
• Fine Art Paper: Textured surface similar to canvas. Artistic applications often prioritize tonality over pure sharpness.

Viewing Distance: The Key Factor

The most overlooked aspect of print quality is viewing distance. A billboard viewed from 50 feet might only need 10-20 PPI to look sharp, while a photo book examined at arm's length needs 250-300 PPI.

Rule of thumb: The farther away your print will be viewed, the lower the required PPI. This is why large format prints don't need as many megapixels as you might think.

Always consider where and how your print will be displayed when determining quality requirements.

LPI (Lines Per Inch) Explained

LPI (Lines Per Inch) refers to the halftone screen frequency used in commercial offset printing. It measures how many rows of halftone dots are printed per inch. Higher LPI values produce finer detail but require higher resolution images.

When a printer uses a halftone screen to reproduce continuous tone images (like photographs), they need your digital image to have a higher DPI than the screen's LPI. The industry standard is 2× the LPI value. This is a concept that is used i offset printing, and not in desktop printing.

Example: A magazine printed at 150 LPI requires images at 300 DPI (150 × 2 = 300). This ratio ensures smooth tones and sharp detail without visible halftone patterns.

• 85 LPI: Newspaper printing - visible dot pattern, DPI: 170-213
• 133 LPI: Standard magazines - good quality, DPI: 266-333
• 150 LPI: Quality publications - very good detail, DPI: 300-375
• 175-200 LPI: Fine art books and premium printing, DPI: 350-500

Why photographers need to know: When preparing images for commercial printing, printers will specify their LPI. Use our LPI/DPI Converter to determine the required image resolution.

DPI (Dots Per Inch) Explained

DPI (Dots Per Inch) refers to the resolution of an inkjet or laser printer used for desktop printing. It measures how many dots the printer can print per inch. Higher DPI means more detail and sharper prints, but the required DPI depends on the print media and LPI required for the print.

Remember that DPI is often used interchangeably with PPI, but PPI is a more accurate measure of the image resolution, and not of the printer's printing resolution. Also remember that DPI is used for desktop printing, and LPI is used for offset printing. You will need to know the LPI of the print medium you are using to determine the required DPI - consult with your offset printing service for this information.

Why photographers need to know: When preparing images for commercial printing, printers will specify their DPI. Use our LPI/DPI Converter to determine the required image resolution.