Winemaking Calculators

By The MyHomeWine Team · Updated

A hydrometer in a trial jar, a wine thief and a notebook with a pencil on a kitchen counter
On this page
  1. Before Fermenting
  2. During Fermentation
  3. Finishing and Bottling
  4. Which Calculator Do I Need?
  5. The Three Numbers Behind Every Calculation
  6. Related Guides

Every batch of wine asks for a different sum at each stage: how much sugar to add and how strong the wine will be before you pitch the yeast, how far fermentation has come while it bubbles, and how much sulfite and how many bottles you need at the end. These free winemaking calculators cover all of it, grouped by the moment you will reach for them.

Before Fermenting

During Fermentation

Finishing and Bottling

Which Calculator Do I Need?

Start from the question in your head and follow it to the right tool.

The question you haveUse this
How much sugar do I add to hit my target gravity?Sugar calculator
My refractometer says Brix. What is that in gravity?Brix to specific gravity or the refractometer calculator
How much honey for a mead of a given strength?Mead calculator
My sample was warm when I read it. Is the number wrong?Hydrometer calculator
How strong is my wine?Wine ABV calculator
How much sulfite goes in before bottling?Sulfite calculator
How many bottles will this batch fill?Wine bottle calculator

If a reading looks wrong or has stopped moving, our guide to a stuck fermentation explains what to check before you trust any calculation.

The Three Numbers Behind Every Calculation

Nearly every winemaking calculation is built from three measurements. Once you know what each one is, the tools above stop being black boxes.

Specific gravity

Specific gravity (SG) compares the density of your must or wine with the density of water. Sugar makes juice denser, so a sweet must reads high, around 1.090 for a typical full-bodied red. As the yeast eats the sugar the reading falls, and it can end just under 1.000 because alcohol is lighter than water. Your hydrometer reads it directly. Our hydrometer guide shows how to take the reading properly.

Brix

Brix is the same idea on a different scale: it measures dissolved sugar, and it is what a refractometer reports. The Brix to specific gravity converter moves between the two scales, so a Brix reading on the day you crush fruit can be compared with a gravity reading later in the batch.

Alcohol by volume

ABV comes from the drop in gravity during fermentation. The common home winemaking equation is ABV = (OG − FG) × 131.25, where OG is the original gravity before the yeast and FG is the final gravity once fermentation has stopped. The wine ABV calculator runs it for you and also shows a second formula for stronger wines.

Are these winemaking calculators free? Yes. Every calculator on this page runs in your browser with no sign-up, no download and no fee, and the results appear as soon as you type your numbers. Use them as often as you like for every batch you make.
Most batches need four: the sugar to add for your target starting gravity, the alcohol by volume from your original and final readings, the sulfite dose before bottling, and the number of bottles the batch will fill. If you use a refractometer, add a Brix conversion at the start.
For the ABV calculator, yes: you need a reading before and after fermentation, and a hydrometer is the usual way to take both. A refractometer can give the starting reading but not the final one once alcohol is present. The sugar, sulfite and bottle calculators need no instrument.

You must be of legal drinking age to make and drink wine. Enjoy it responsibly.