Which ABV formula should I use?

Use the Advanced (Terrill) method for most homebrew scenarios as it compensates for non-linearity at higher gravities. The Standard method is simpler and close enough for low to moderate OG beers.

Do I need hydrometer temperature correction?

Correct if your sample temperature differs from the hydrometer calibration temperature (often 20°C or 60°F). Significant differences can bias OG/FG and final ABV.

homebrew abv calculator

A precise, accessibility-first tool for homebrewers to compute Alcohol by Volume (ABV) and related metrics.

Gravity Inputs

Original Gravity (OG)

Typical range: 1.030–1.120.

Final Gravity (FG)

Must be less than OG for a normal fermentation.

Formula

Standard (131.25) Advanced (Terrill)

Advanced method is recommended for higher gravities.

Hydrometer Temperature Correction

Apply correction

Enable if measurements were taken away from hydrometer calibration temperature.

ABV

—

ABW —

Original Extract (°P) —

Final Extract (°P) —

Real Extract (°P) —

Apparent Attenuation —

How to use

Enter Original Gravity (OG) and Final Gravity (FG), choose the calculation method, and optionally enable temperature correction if your measurements were taken away from hydrometer calibration temperature.

Methodology

The calculator derives ABV and ABW from OG and FG. It converts specific gravity to Plato using the ASBC cubic relationship, then computes Real Extract and Apparent Attenuation using standard brewing equations.

Full original guide (expanded)

This tool provides Standard and Advanced (Terrill) ABV calculations, hydrometer temperature correction, and Plato-based analytics used in professional brewing. It supports OG/FG validation, optional correction for sample and calibration temperatures, and outputs ABV, ABW, Original Extract, Final Extract, Real Extract, and Apparent Attenuation.

Temperature correction notes

Correction is recommended when the sample temperature differs from hydrometer calibration temperature.
Valid range: 0–100 °C (32–212 °F).

FAQ highlights

Advanced (Terrill) is recommended for higher gravities.
ABW is derived from ABV and the beer’s density.
Plato values enable professional extract and attenuation calculations.

Formulas

ABV (Standard):

\[ ABV_{\%} = (OG - FG) \times 131.25 \]

ABV (Advanced/Terrill):

\[ ABV_{\%} = \frac{76.08 \times (OG - FG)}{1.775 - OG} \times \frac{FG}{0.794} \]

Plato from Specific Gravity:

\[ P = -616.868 + 1111.14\,SG - 630.272\,SG^{2} + 135.997\,SG^{3} \]

Real Extract:

\[ RE = 0.1808 \times P_{OG} + 0.8192 \times P_{FG} \]

Apparent Attenuation:

\[ AA_{\%} = \frac{P_{OG} - P_{FG}}{P_{OG}} \times 100 \]

Alcohol by Weight:

\[ ABW_{\%} = \frac{0.79336 \times ABV_{\%}}{FG} \]

Hydrometer Correction:

\[ SG_{corr} = SG_{obs} \times \frac{CF(T_{sample})}{CF(T_{cal})} \] \[ CF(T) = 1.00130346 - 1.34722124\times10^{-4}T + 2.04052596\times10^{-6}T^{2} - 2.32820948\times10^{-9}T^{3} \]

Citations

Everyday Life — calcdomain.com: https://calcdomain.com/lifestyle-everyday

Hobbies — calcdomain.com: https://calcdomain.com/subcategories/hobbies

asbcnet.org — Methods of Analysis: https://www.asbcnet.org/exams-resources/Resources/Pages/Methods.aspx

Changelog

0.1.0-draft — 2026-01-19: Initial audit spec draft generated from HTML extraction (review required). Verify formulas match the calculator engine and convert any text-only formulas to LaTeX. Confirm sources are authoritative and relevant to the calculator methodology.

✓ Verified by Ugo Candido

Last Updated: 2026-01-19

Version 0.1.0-draft