I checked result for inch and mm dimensions.

- inch calculus is correct.
- mm calculs is NOT correct.

the problem is in nominal size.
example:
in english we have 8".
In metric we have 200mm but 8"*25.4=203.2mm and all small differences due to unit conversions cause wrong result.

So is better to use the inch measures.

i made an excel check, how can i attach it here?