In 2018 I had some free time and I was 'angry' at many for failing to have a printer able to print two-sided, if such equipment was still necessary at all. I thought about how to learn a bit of javascript while building something (if minimally) useful, hence this calculator.
Printing only on one side has obvious environmental costs, but also financial ones. I tried to account for the latter, though not extensively (e.g. does not account for cost of extra space occupied in archives if single-sided). Of course, I am also aware the manufacturing of a new printer hurts the environment, but this is not such easy math.
Live green.