Counted cross stitch is the one craft here where the arithmetic is exact. A stitch occupies one square of the fabric, the squares are evenly spaced, and the count printed on the bolt says how many of them fit in an inch — so the finished size of a design follows from the stitch count with nothing left to estimate. Thread is the same story one level down: a stitch is two diagonals of a known square, which gives a floor for how much floss a colour will take. What the geometry cannot tell you is how much thread disappears into the back of the work, so that part is a factor you set rather than a number we invent.
Tell us what is missing and where its numbers should come from.
What should it convert, calculate or generate, and where would the authoritative numbers come from? A link to the standard or publication that defines them is the most useful thing you can send.
Copies this page address so you can paste it wherever you report it.
Two kinds of thing live here. The size charts are transcribed from the Craft Yarn Council standards row by row, keeping the repeated numbers and the gaps exactly as the standard prints them. The calculators are arithmetic over figures you supply — your swatch, your ball band — because the alternative is an average of somebody else's knitting, and averages are what make a sweater come out the wrong size. Every tool carries worked examples that run as tests, so a change that breaks one of them never ships.