Changes

Knowing that numerous factors influence the way file sizes for print are calculated, it’s evident that there’s no one-fits-all approach. What will work for a standard 10x15 photo won’t be the best option for an A4 poster, and vice versa. Therefore, the more you know about image resolution and aspect ratio, the easier it will be to calculate the perfect file size for your specific need.

Raster images, such as photos and illustrations, consist of pixels—colored squares positioned in a certain way to form a picture. Image resolution is the density of the pixels. Low-resolution images have fewer pixels and, therefore, lose their quality when scaled manually. High-resolution images have at least 300 PPI (pixels per inch) and look good in large formats, e.g., billboard posters.

If you know a photo's dimensions in pixels, you can calculate its resolution when printed in a particular format. To do that, divide a picture's length (in pixels) by the chosen print size (in inches). The number you’ll get will be the resolution. If it’s 300 PPI or more, the printed version will look as clear and detailed as the source file.

[https://support.squarespace.com/hc/en-us/articles/115008538927-Understanding-aspect-ratios Aspect ratio] is the ratio of width and height that shows actual image proportions. The width is usually the first number, and the height is the second. When you have a visual with an aspect ratio of 16:9, it will maintain its proportions when printed in an aspect ratio of 32:18, for instance. However, if you try to use an original 9:9 image and fit it to 32:18, the result will be unsatisfactory, as the picture’s original proportions will be lost and it will look stretched.