In what dimensions can I print a photo shot on Canon EOS 2000D at full resolution and save the photo as JPEG in a 3:2 aspect ratio? Let's assume I want to print it with 600 dpi.
Printing a photo at anything over 300 dpi is wasted effort, since the printers can't do it and our eyes can't see it. A print shop machine will automatically resample it smaller first.
A 6000x4000 pixel image is aspect ratio 3:2.
This 3:2 shape will print:
4x6 inches will print at 1000 dpi
8x12 inches will print at 500 dpi
12x18 inches will print at 353 dpi
16x24 inches will print at 250 dpi
If you want to print other print size shapes, like 8x10 or 11x14 inches, or like metric A4 size, those are different shapes than 3:2 and the image will need to be cropped to fit the paper shape first. If you order it as is to be printed on say 8x10 inches, the paper shape will crop it, but you are advised to crop it first yourself to include the exact image portion you want retained (to avoid surprises).
My site has a printing dpi calculator at https://www.scantips.com/calc.html that (given what image you have and what size you want to print it) will calculate exactly what you need to do to print a specific paper size and shape (in terms of crop and resample).
For example, to print in metric A4 paper size (210x297 mm), it says:
Printing and Scanning DPI Calculator
Print Paper Size: 210 x 297 mm
Scroll to results Then for this print size:
For existing digital Images
Specify size (pixels) of the Image to be printed:
Width x Height 6000 x 4000 pixels
Button 1 result: Fitting short side of 297×210 mm paper.
Prints 11.693×8.268 inches (297×210 mm) at 484 dpi (190 pixels/cm).
6000 pixels / 484 pixels per inch = 297 mm
4000 pixels / 484 pixels per inch = 210 mm
This 6000×4000 pixel image size is 24 megapixels, Aspect ratio 3:2 (1.5:1). Paper aspect ratio 1.414:1 (1.41:1)
Cropping the 6000×4000 image to 5657×4000 would fit the 297×210 mm 1.414:1 paper shape at 484 dpi.
484 dpi is excessively High resolution for printing photos.
First do any suitable crop that will match the paper aspect.
Then resampling smaller to 3508×2480 pixels (8.7 megapixels) will fit 297×210 mm paper at 300 dpi.
There is text below the calculator with more detail.
The 2000D has a max resolution of 6000×4000 pixels, an aspect ratio of 3:2; therefore at 600dpi you can print it at (6000 / 600) × (4000 / 600) = 10 × 6⅔ inches. Saving the photo as JPEG doesn't make a difference to the resolution, but may affect the quality.
Printing arbitrarily at 600DPI doesn't make much sense.
A Letter/A4/magazine page at 300DPI about 8.5Mpix, at 600DPI is would be 34Mpix. 600DPI is already overkill for photography, it is mostly useful for text.
The bigger the picture, the farther away the viewers are, so that the required resolution is lower. It actually evens out so you don't need gigapixels to print a billboard image, you still need the same 8.5Mpix for the same perceived sharpness (but it will be printed at 20DPI and viewed from 10 meters away).