Nope, I just spent 15 minutes reading the original paper and can’t make any sense of what he is calculating.

International dollars are normalized to USD, so there’s no conversion necessary. The figure he quotes of 63 min per dollar converts to $8343/year. However, his original paper states that he created this measure by inverting income, so the number 8343 is his starting point.

The closest guess I have is that is derived from the poverty line for a family of four, $32150 (which divided by four is $8037).

If that is the case, what he is really doing is comparing poverty line definitions between countries.