You can get higher precision by following a brew and take continually SG samplings thereby turn these data into a better polynomial.
In above (picture) dataset of measured hydrometer samplings vs. RAPT Pill reported gravity (SG) the user can derive a polynomial. In this case a 3rd degree polynomial seems to fit over a 2nd by the R-value.
When entering this polynomial in iBLOPPER CLOUD (max. 200 ciffers) it should be entered as follows:
225.59*sg*sg*sg – 691.88*sg*sg + 708.17*sg – 240.88
The exceel file to do this can be downloaded her:
Exceel sheet polynomial (216 downloads)