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DPI Calculator

PhotographyImage Size and Print
Find
Result —
Resolution (DPI)
—
Print size (inches)
—
Print size (centimetres)
—
Megapixels
—
Typical use
—

DPI is the image's pixel width divided by the print width in inches. A 3000 × 2400 px photo printed 10 inches wide gives 3000 ÷ 10 = 300 DPI and comes out 8 inches tall. To go the other way, divide pixels by the DPI you want: 2400 px at 300 DPI is an 8 in edge.

About this tool

Photographers sending files to a lab, designers preparing artwork for a printer and anyone resizing a scan all hit the same question: is this image big enough for the print? This calculator answers it in two directions. Give it the pixel dimensions and a print width in inches or centimetres and it returns the resulting DPI, the matching print height and a rough note on what that resolution suits. Or give it a target DPI and it returns the print size in both inches and centimetres, along with the megapixel count. It treats DPI and PPI as the same pixels-per-inch figure, which is how print labs use the term. It cannot tell you whether the pixels themselves are sharp: an upscaled or heavily compressed file still prints soft at 300 DPI.

How to use it

  1. Choose what to find

    Pick DPI for a print size, or Print size at a DPI.

  2. Enter the pixel dimensions

    Type the image width and height in pixels, as shown in your editor or the file properties.

  3. Enter the print width or DPI

    For DPI, type the print width and set inches or centimetres in the attached unit menu. For size, type the target DPI.

  4. Read the results

    The result, print size in both units, megapixels and a typical-use note update as you type, with the working shown below.

Examples

3000 × 2400 px on a 10 in print

Find
DPI for a print size
Image width
3000
Image height
2400
Print width
10
Unit
in

Result Result: 300 DPI
Resolution (DPI): 300
Print size (inches): 10 × 8 in
Print size (centimetres): 25.4 × 20.32 cm
Megapixels: 7.2
Typical use: Photo quality (300+ DPI)

  1. DPI = 3000 px ÷ 10 in = 300
  2. Print height = 2400 px ÷ 300 = 8 in
  3. Centimetres = inches × 2.54

A 7.2-megapixel image spread across 10 inches lands exactly on 300 DPI, the usual target for photo prints, and comes out 8 inches tall.

2400 × 3000 px at 300 DPI

Find
Print size at a DPI
Image width
2400
Image height
3000
Print resolution
300

Result Result: 8 × 10 in
Resolution (DPI): 300
Print size (inches): 8 × 10 in
Print size (centimetres): 20.32 × 25.4 cm
Megapixels: 7.2
Typical use: Photo quality (300+ DPI)

  1. Width = 2400 px ÷ 300 DPI = 8 in
  2. Height = 3000 px ÷ 300 DPI = 10 in
  3. Centimetres = inches × 2.54

This portrait image makes a sharp 8 × 10 in print, the classic studio enlargement.

3000 px across 50.8 cm

Find
DPI for a print size
Image width
3000
Image height
2000
Print width
50.8
Unit
cm

Result Result: 150 DPI
Resolution (DPI): 150
Print size (inches): 20 × 13.33 in
Print size (centimetres): 50.8 × 33.87 cm
Megapixels: 6
Typical use: Fine for posters at arm's length

  1. Print width = 50.8 cm ÷ 2.54 = 20 in
  2. DPI = 3000 px ÷ 20 in = 150
  3. Print height = 2000 px ÷ 150 = 13.33 in
  4. Centimetres = inches × 2.54

50.8 cm is 20 inches, so the same file drops to 150 DPI, which still works for a poster seen from a step back.

How it is calculated

DPI = pixel width ÷ print width (in); print width (in) = pixel width ÷ DPI; cm = in × 2.54

pixel width
Number of pixels along the edge being printed
print width
Physical length of that edge, converted to inches
DPI
Dots (pixels) per inch on paper

Resolution on paper is simply pixels spread over distance. Centimetre widths are divided by 2.54 first, because the inch is defined as exactly 2.54 cm. The height follows from the same DPI, so the aspect ratio is preserved. The typical-use note uses common print-lab bands: 300 and above for photos held in the hand, 150 to 200 for posters, and lower only for banners viewed from metres away.

When not to use it

  • Choosing printer hardware DPI settings, which describe ink dots rather than image pixels.
  • Sizing images for screens, where only pixel dimensions matter.
  • Judging sharpness of an upscaled file, since added pixels carry no new detail.

Common mistakes

  • Changing the DPI field in an editor without resampling and expecting more detail.
  • Entering a centimetre width while the unit menu is still set to inches.
  • Measuring the frame opening instead of the print, which ignores the mat border.
  • Assuming 72 DPI is a web standard that affects how images look on screen.

Frequently asked questions

Is DPI the same as PPI?

Strictly, PPI counts image pixels per inch and DPI counts printer ink dots. Print labs and most software use DPI loosely to mean pixels per inch of the finished print, and that is the figure calculated here.

What DPI do photo labs ask for?

Most labs quote 300 DPI at the final print size for prints held in the hand, such as 6 × 4 or 10 × 8 in. Many accept 240 to 250 without visible loss, and large posters often print well at 150.

How many pixels do I need for an 8 × 10 print at 300 DPI?

Multiply each edge by the DPI: 8 × 300 = 2400 px and 10 × 300 = 3000 px, so 2400 × 3000 px, about 7.2 megapixels.

Does setting 300 DPI in an editor make the image sharper?

No. Without resampling, changing the DPI tag only changes the suggested print size; the pixels stay the same. Resampling up adds interpolated pixels, which smooths edges but cannot recover detail the camera did not capture.

Why does viewing distance matter?

Fine detail becomes invisible as you step back. A billboard at 20 DPI looks crisp from the road, while a photo book page needs around 300 because it is read at 30 cm.

Why is the height calculated from the width?

Printing without cropping keeps the image aspect ratio, so the same DPI applies to both edges. If the paper shape differs from the image, part will be cropped or a border will appear.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 20). DPI Calculator. Tools Directory. Retrieved October 27, 2026, from https://tools.milunir.com/photography/image-size-and-print/dpi-calculator/

MLA

Tools Directory Editorial Team. “DPI Calculator.” Tools Directory, 20 Oct. 2026, https://tools.milunir.com/photography/image-size-and-print/dpi-calculator/. Accessed 27 Oct. 2026.

Chicago

Tools Directory Editorial Team. “DPI Calculator.” Tools Directory. Last modified October 20, 2026. Accessed October 27, 2026. https://tools.milunir.com/photography/image-size-and-print/dpi-calculator/.

Link<a href="https://tools.milunir.com/photography/image-size-and-print/dpi-calculator/">DPI Calculator – Tools Directory</a>