I bought a refractometer (the one with the brix scale only) and am using it along with Morebeers spreadsheet to track the gravity of my last brew. I have also been taking a reading with a hydrometer. So far the reading in the spreadsheet and the hydrometer have matched, but when I switch measurements in Beersmith, the program tells me that the final gravity estimate much lower than the brix reading I am getting with the refactometer. Is this because Beersmith doesn’t account for the alcohol but the spreadsheet does?
No, it’s because the reading from the refractometer isn’t the actual gravity in Brix/Plato. It’s just an estimated SG based on an assumed relationship between the refractive index and the sugar content. When there’s alcohol in solution, that assumption is no longer accurate.