Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

Refracto - Refractometer Calculator for Homebrewers

Refracto is a tool for homebrewers that will help you to convert your refractometer measurements during a fermentation process from °Brix to SG or °Plato. It automatically compensates the alcohol effect during fermentation.

Refracto is available on the App Store

How to use Refracto

  1. Swipe vertically to enter your initial refractometer reading, i.e. the measurement result for the original wort, just before adding the yeast.
  2. Swipe vertically to enter your current refractometer reading, i.e. a measurement result after the fermentation process has started.
  3. Swipe horizontally to switch between the computation modes. Available modes are the Standard formula according Louis K. Bonham, the quadratic and linear formula of Petr Novotný, and the cubic and linear formulas of Sean Terrill. The Standard and Novotný formulas are recommended for general purpose use.
  4. You are done! In the upper section you can now see the computed values for your beer.

How to use Refracto

Computed Values

Refracto computes and immediately updates the following values whenever you change one of its input values:

  1. The resulting original gravity (OG) and apparent final gravity (FG) in °Plato.
  2. The resulting original gravity (OG) and apparent final gravity (FG) in SG.
  3. The amount of sugars consumed by the yeast so far, displayed as apparent attenuation on the top and the estimated alcohol content as percent by volume on the bottom.

Computed Values