How do I show 0-100% of battery between to point of voltages?

I have 7S battery where I have mounted a BMS that only use 3,7 to 2,8 (7S 25,9 - 17,65v ) voltage on each cell. That’s is in total 32 % of the battery capacity. Now I want to show the 0-100 % between these voltage.? How do I do this?

If you didn't have to code it, could you write the math for what you want? To get a percentage, you divide the part (the smaller voltage) by the whole (the full 100% voltage) and then multiply by 100.

Have a feeling the Op might be looking for "mapping" although the mapping reference in Arduino tend to warn against fractions.
Might be able to do with whole numbers and then divide down??