Almost all modern PC and mobile device users know something about resolutions and can differentiate between a camera with a better sensor, a monitor with a better image, and a video with better quality by the number of pixels. However, when it comes to transferring content from "digital" to live paper, many have problems.
Table of Contents
- 1 Print resolution
- 2 What is DPI
- 3 How many pixels do you need for quality printing?
- 4 What is the pixel size of A5, A4, A3, A2, A1 and A0 sheets based on DPI?
- 5 How do you determine the number of pixels corresponding to the size of a sheet of paper?
The sticking point is actually that when printing we have a new variable that the average user is not familiar with: print resolution. Only a specialist in printing, advertising, photo printing, etc., can easily name the minimum resolution required for the creation of a physical image on a huge billboard, a small business card or a t-shirt with a print. In this material we will focus on common printing examples, which each of us can find in everyday life (printing on A4, A3, A2, A1, A0 sheets), and we will derive a simple formula to calculate the necessary resolution for any task .
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What is DPI
Thus, the print resolution is measured in DPI (dots per inch), that is, in the number of dots per square inch (1 inch = 25,4 mm). The easiest way to explain this parameter is to use an outdated device like a dot matrix printer - in this case, DPI is the number of needle strokes in a 1 inch by 1 inch area.
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How many pixels do you need for quality printing?
Of course, DPI doesn't matter as long as the image remains on your monitor, but the resolution of the source file does. You cannot print a high quality photo on an A4 sheet at 300 DPI if the source image on your screen is 1024 × 768 pixels.
Standard DPI Values Used in Printing
The 75 DPI resolution is for text documents;
150 DPI resolution is the minimum quality for printing images;
300 DPI resolution is the generally accepted quality for photo printing.
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What is the pixel size of A5, A4, A3, A2, A1 and A0 sheets based on DPI?
Below you can find the correspondence between the resolution values of the source image and the size of the sheet of paper on which it will be printed (the data is calculated for print resolutions of 75 DPI, 150 DPI and 300 DPI) .
A5 size (148 × 210 mm) in pixels
With DPI = 75, the resolution of A5 format has 437 × 620 pixels.;
With DPI = 150, A5 resolution has 874 × 1240 pixels.;
With DPI = 300, A5 resolution has 1748 × 2480 pixels..
A4 size (210 × 297 mm) in pixels
With DPI = 75, A4 resolution has 620 × 877 pixels.;
With DPI = 150, A4 resolution has 1240 × 1754 pixels.;
With DPI = 300, A4 resolution has 2480 × 3508 pixels..
A3 size (297 × 420 mm) in pixels
at DPI = 75, the resolution of A3 format has × 877 1240 pixels;
at DPI = 150, the A3 resolution has × 1754 2480 pixels;
at DPI = 300, the A3 resolution has × 3508 4961 pixels.
A2 size (420 × 594 mm) in pixels
at DPI = 75, the resolution of A2 format has 1240 × 1754 pixels.;
With DPI = 150, A2 resolution has 2480 × 3508 pixels.;
With DPI = 300, A2 resolution has 4961 × 7016 pixels.
A1 size (594 × 841 mm) in pixels
at DPI = 75, the resolution of A1 format has 1754 × 2483 pixels;
With DPI = 150, A1 resolution has 3508 × 4967 pixels.;
With DPI = 300, A1 resolution has 7016 × 9933 pixels.
A0 size (841 × 1189 mm) in pixels
at DPI = 75, the resolution of A0 format is 2483 × 3511 pixels.;
With DPI = 150, A0 resolution has 4967 × 7022 pixels;
With DPI = 300, A0 resolution has 9933 × 14043 pixels.
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How do you determine the number of pixels corresponding to the size of a sheet of paper?
As mentioned above, a print resolution of 300 DPI is considered sufficient quality to transfer graphics to paper. To print a photo or simply an image in this quality on A4 size paper (297 × 210 mm) it is necessary to have an original image resolution of 3508 × 2480 pixels, if the quality requirements are reduced by half, to 150 DPI , the original resolution of 1754 × 1240 pixels will suffice, and 75 DPI and a resolution of 877 × 620 pixels are sufficient for printing text.
In any non-standard situation, you can resort to forbidden techniques and use math. For example, to find out the necessary resolution of the initial image for printing we can construct the following formula:
R = L × PPP / 25,4
R - The desired resolution of the side;
L - Side length in mm;
DPI - required print quality;
25,4 - Translate inches into centimeters (1 inch is approximately 2,54 cm) and multiply by 10 to convert it to millimeters.
You have to print an image with a quality of 150 DPI on an A4 sheet (297 × 210 mm). Obtaining:
R (height) = 297 × 150 / 25,4 = 1754 pixels;
R (width) = 210 × 150 / 25,4 = 1240 pixels.
Consequently, the original resolution should be 1754 × 1240 pixels, which is the same as in the table above.