acalculator

What DPI will my print have?

Type your image size in pixels and the size you want to print it. The DPI calculator gives the print resolution, the largest print at your target DPI, and the pixels that print size needs.

Your numbers

Units
Print resolution
300

A 3,000 × 2,400 pixel image printed 10 in × 8 in has 300 DPI.

DPI across
300
DPI down
300
Largest print width at the target (in)
10
Largest print height at the target (in)
8
Largest print width at the target (cm)
25.4
Largest print height at the target (cm)
20.32
Pixels needed across
3,000
Pixels needed down
2,400
Meets the target?
Yes

Print resolution: 300. A 3,000 × 2,400 pixel image printed 10 in × 8 in has 300 DPI.

How to calculate

Works out the print resolution in dots per inch (DPI) of an image from its pixels and the print size, the largest print at a target DPI, and the pixels a print size needs.

Example with the default inputs (Image width (pixels) 3,000, Image height (pixels) 2,400, Print width 10 in, Print height 8 in, Target DPI 300): A 3,000 × 2,400 pixel image printed 10 in × 8 in has 300 DPI.

Method: DPI across = pixel width ÷ print width (in); DPI down = pixel height ÷ print height (in); print resolution = the lower; largest print = pixels ÷ target DPI; pixels needed = ⌈print size (in) × target DPI⌉.

  • The image fills the print without cropping or borders; when its shape differs from the print, the lower DPI applies to the whole print.
  • DPI here means image pixels per printed inch (also called PPI); a printer’s own ink dots per inch are a separate setting.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Image width (pixels) 3,000, Image height (pixels) 2,400, Print width 10 in, Print height 8 in, Target DPI 300 gives Print resolution 300, DPI across 300, DPI down 300, Pixels needed across 3,000, Pixels needed down 2,400, Meets the target? Yes.Source: ScanTips, Printing and Scanning Resolution DPI Calculator (print size = pixels ÷ resolution), https://www.scantips.com/calc.html (3,000 pixels at 300 dpi prints 10 inches)
  2. Image width (pixels) 1,500, Image height (pixels) 1,200, Print width 10 in, Print height 8 in, Target DPI 300 gives Print resolution 150, Largest print width at the target (in) 5, Largest print height at the target (in) 4, Largest print width at the target (cm) 12.7, Meets the target? No.Source: ScanTips, Printing and Scanning Resolution DPI Calculator (print size = pixels ÷ resolution), https://www.scantips.com/calc.html
  3. Image width (pixels) 4,000, Image height (pixels) 3,000, Print width 7.874 in, Print height 5.906 in, Target DPI 300 gives Print resolution 508, Pixels needed across 2,363, Pixels needed down 1,772.Source: ScanTips, Printing and Scanning Resolution DPI Calculator (print size = pixels ÷ resolution), https://www.scantips.com/calc.html
  4. Image width (pixels) 3,000, Image height (pixels) 2,000, Print width 10 in, Print height 8 in, Target DPI 300 gives DPI across 300, DPI down 250, Print resolution 250, Meets the target? No.Source: ScanTips, Printing and Scanning Resolution DPI Calculator (print size = pixels ÷ resolution), https://www.scantips.com/calc.html

How it works

Print sizes are turned into inches with 1 in = 2.54 cm = 25.4 mm exactly.

  • DPI across = image width in pixels ÷ print width in inches.
  • DPI down = image height in pixels ÷ print height in inches.
  • Print resolution = the lower of the two: the whole print gets at least that many dots per inch.
  • Largest print at the target = width in pixels ÷ target DPI by height in pixels ÷ target DPI, in inches, and the same × 2.54 in centimetres.
  • Pixels needed = print width × target DPI and print height × target DPI, each rounded up to a whole pixel.
  • Meets the target? Yes when the print resolution is at least the target DPI, otherwise No.

Rules. Pixel counts are whole numbers from 1 to 1,000,000. Print sizes are from 1 mm to 100 m. The target DPI is from 1 to 10,000. Every set of values in range has an answer.

Exact arithmetic. Each print size is read as the exact decimal you typed, in the unit you typed it in (the decimal with the fewest significant digits, in inches, centimetres or millimetres, that gives the same stored number; on a tie the first unit wins). Every step is an exact fraction, so 3,000 px over 10 in is exactly 300 DPI, and pixels needed are rounded up from the exact value.

Output format. Decimals and significant figures below are the most shown; trailing zeros are dropped (23.0 shows as 23, money keeps its cents). DPI values show 2 decimals; the largest print size shows 2 decimals in inches and 2 in centimetres, each worked out exactly in that unit and rounded half up (3,591 px at 600 DPI is 5.985 in, shown 5.99). Pixels needed are whole numbers.

Assumptions

  • The image fills the print with no border and no crop.
  • Default target: 300 DPI, a common choice for photo prints.

Worked examples by hand

3000 × 2400 px on a 10 × 8 in print. 3,000 ÷ 10 = 300 and 2,400 ÷ 8 = 300 DPI: meets 300. Pixels needed 10 × 300 = 3,000 and 8 × 300 = 2,400.

1500 × 1200 px on 10 × 8 in. 1,500 ÷ 10 = 150 DPI: below 300. At 300 DPI the largest print is 1,500 ÷ 300 = 5 in by 1,200 ÷ 300 = 4 in.

4000 × 3000 px on 20 × 15 cm. 20 cm = 7.874 in, so 4,000 ÷ 7.874 = 508 DPI (exactly 4,000 × 2.54 ÷ 20). At 300 DPI the print needs 7.874 × 300 = 2,362.2, so 2,363 px across, and 5.906 × 300 = 1,771.7, so 1,772 px down.

A 3:2 image on an 8 × 10 print. 3000 × 2000 px at 10 × 8 in: 300 DPI across, 2,000 ÷ 8 = 250 DPI down; print resolution 250.

Other questions people ask

How do I calculate DPI for printing?

Divide the image’s pixels by the print size in inches. A 3000 × 2400 pixel image printed 10 × 8 in has 3,000 ÷ 10 = 300 dots per inch across and 2,400 ÷ 8 = 300 down.

How big can I print an image at 300 DPI?

Divide each pixel count by 300. A 1500 × 1200 image prints 5 × 4 in at 300 DPI; at 150 DPI it prints 10 × 8 in, with fewer pixels in each inch.

What DPI do I need for a good print?

300 DPI is a common target for photos and small prints viewed up close. Large posters and banners viewed from a distance often look fine at 150 DPI or less. Set the target DPI to what your printer or print shop asks for.

Why are the DPI across and down different?

The image and the print have different shapes. A 3000 × 2000 (3:2) image on an 8 × 10 print gets 300 DPI across but only 250 DPI down, so the page reports the lower value; in practice the image is cropped or gets a border.

Is DPI the same as PPI?

For sizing an image, people use the two words for the same thing: image pixels per printed inch. Strictly, PPI is pixels and DPI is the ink dots a printer lays down. For a screen’s pixel density, use the PPI calculator; for mouse sensitivity, the eDPI calculator.

Does changing the DPI setting in my photo editor change the image?

Not if you only change the DPI number without resampling. The pixels stay the same; only the print size the file asks for changes. Adding pixels by resampling cannot add real detail.