I just got a refractometer. How do I convert my readings to hydrometer readings?
Tools abound online, one linked below. One note is that refractometers are not accurate when in the presence of alcohol. Some calculators do a good job of compensating for this, but hydrometers are the best tool post fermentation.
so it seems you need to be well educated to use a Refractometer. there is no simple answer to you question but I recently found this article http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/ which has helped me understand what a refractometer is and the limitations of its accuracy.