Set a specific Width, Height, and DPI

Example: we have a square image from the internet, and we need to make it 9" x 3.7" at 300 DPI. We will do it for free using Photopea.com.

*** 300 DPI means that we should have 300 Dots (pixels) Per Inch. If we multiply 9 inches by 300 pixels per inch, our image should be 2700 pixels wide. 3.7 x 300 = 1100 pixels tall.

We have a square image, but 9 x 3.7 inches is not a square. We will resize our image first (while keeping the width / height ratio), and then, we will crop it (cut away parts at the top and the bottom of the square), to get a wide rectangle.

Resizing

Open your image in Photopea (File - Open), and then, press Image - Size. Set the units to Inches, and set the Width to 9 and the Height to 9 (one side should have the required size, another can be larger - we will cut it later). Set the DPI to 300, and press OK.

Cropping

The easiest way to crop is using the Canvas Size. Press Image - Canvas Size, set the units to Inches, and enter the reqizred size of 9" x 3.7". Press OK, and we are done! Now, press File - Export As - JPG, and save the result to your computer :)

Comments

Image Size stretches the content of the image. If there was a car in our image, which was 2 inches big, we can make it 3 inches big. Canvas Size ignores the content, it only cuts away parts from the sides. The size of each object stays the same.