Specific Gravity Calculator
Choose which reading you have on hand.
Sugar content from a refractometer.
Specific gravity
1.048
Potential ABV (to 1.010 FG)
5.0%
A 12.0°Bx reading converts to a specific gravity of 1.048, giving a potential 5.0% ABV if fermented down to a typical final gravity of 1.010.
Quick answer
Specific gravity (SG) measures a liquid's density against water, and it converts directly to Brix, the percentage of sugar by weight. A 12°Bx reading works out to roughly 1.048 SG. Enter either reading into this specific gravity calculator to convert instantly and see potential ABV.
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Specific Gravity Calculator is one of brewing and alcohol making tools on OneCalculate — see the full set for this category.
Browse BrewingHow it works
This specific gravity calculator converts between Brix (°Bx), a measure of sugar content by weight, and specific gravity (SG), a measure of density relative to water. The two scales describe the same underlying sugar concentration, so any brew gravity calculator that knows one can derive the other with a standard polynomial conversion, the same one used to build Brewer’s Friend’s Plato to specific gravity conversion reference — Plato and Brix are close enough in practice that the same formula covers both.
Converting Brix to SG uses this formula:
SG = 1.000019 + 0.0038661 × Brix + 0.00001312 × Brix²So a 12°Bx reading gives SG = 1.000019 + 0.0038661 × 12 + 0.00001312 × 144 = 1.048. Going the other direction — from SG back to Brix — means solving the same quadratic for Brix, which this hydrometer calculator does automatically using the quadratic formula so you never have to rearrange it by hand.
Once SG is known, this original gravity calculator also estimates potential alcohol, assuming fermentation finishes at a typical final gravity of 1.010:
Potential ABV % = (SG − 1.010) × 131.25 (only when SG is above 1.010)That’s the same gravity-drop constant used throughout homebrewing to turn a gravity difference into an alcohol-by-volume percentage, so a 1.048 SG reading implies a potential ABV of roughly 5.0% if fermentation runs to completion at 1.010.
Worked example
Priya, a home winemaker in Margaret River, WA, presses a batch of chardonnay grapes and checks the juice with a refractometer before pitching yeast: 22.0°Bx. She types that into the calculator, which converts it to a specific gravity of 1.091 and a potential ABV of 10.7% — useful context for picking a suitable wine yeast strain before fermentation even starts.
Three days into a vigorous ferment, she pulls a sample and takes a hydrometer reading instead: 1.020 SG. Switching the calculator to specific gravity to Brix mode converts that back into sugar terms, showing roughly 5.1°Bx-equivalent, letting her log fermentation progress in the same units she started with.
| Stage | Reading | Converted value |
|---|---|---|
| Pre-fermentation (refractometer) | 22.0°Bx | 1.091 SG |
| Mid-fermentation (hydrometer) | 1.020 SG | 5.1°Bx-equivalent |
Tracking both scales side by side lets Priya confirm the ferment is progressing normally without needing two separate reference charts on the wall of her shed.
Frequently asked questions
What is specific gravity in brewing?
Specific gravity (SG) is the density of your wort, must or juice compared with plain water, which has an SG of exactly 1.000. Higher SG means more dissolved sugar, so brewers and winemakers use it before and after fermentation to track how much sugar has converted into alcohol.
How do I convert Brix to specific gravity?
Plug your Brix reading into SG = 1.000019 + 0.0038661 × Brix + 0.00001312 × Brix², the standard polynomial conversion. This specific gravity calculator does the arithmetic for you, so a 12°Bx refractometer reading returns an SG of about 1.048 instantly.
What's a typical original gravity for beer, wine, cider or mead?
Most beers start around 1.040–1.060 OG, ciders around 1.045–1.055, and wine or mead musts often start well above 1.090 because grape juice and honey carry more fermentable sugar. Use this original gravity calculator to check a reading against those typical ranges.
Why do my refractometer and hydrometer readings disagree?
A refractometer reads in Brix and is unaffected by temperature swings the way a hydrometer is, but once alcohol is present a refractometer's raw reading needs a correction factor to match a true hydrometer SG. Before fermentation starts, though, the two should agree closely.
How do I estimate potential alcohol from a gravity reading?
This brew gravity calculator estimates potential ABV as (SG − 1.010) × 131.25, assuming fermentation finishes at a typical final gravity of 1.010. It's a starting estimate — your yeast strain and fermentability of the wort will shift the real final gravity up or down.
Is Brix the same as specific gravity?
No, but they measure closely related things and convert directly into one another. Brix is degrees of sugar by weight on its own scale, while specific gravity compares density to water on a 1.000 baseline — this hydrometer calculator converts cleanly between the two either way.
Do I need a hydrometer or a refractometer to use this calculator?
Either works. Take a Brix reading from a refractometer or an SG reading from a hydrometer, select the matching conversion direction, and enter the number — the alcohol gravity calculator handles the rest of the maths for you.
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Written and verified by Nirbhay Tripathi
Last updated 18 August 2026
All rates on this page are verified againstBrewer's Friend — Plato to specific gravity conversion referenceon 18 August 2026. See our methodology for the full update calendar.