What is original gravity?

Original gravity (OG) is a measure of the total sugar content dissolved in your wort before fermentation begins. It is expressed as a specific gravity relative to water (1.000). A typical session ale might have an OG of 1.040, while a barleywine can exceed 1.100.

What is PPG (points per pound per gallon)?

PPG is the number of gravity points a grain contributes when one pound is dissolved in one gallon of water at 100% extraction efficiency. Two-row pale malt is typically 37 PPG, crystal malts around 34 PPG, and liquid malt extract around 36 PPG.

What efficiency should I use?

All-grain homebrewers typically see 65–75% mash efficiency. Partial mash setups are similar. Liquid and dry malt extract are pre-converted, so use 100% efficiency for those. If you are unsure, start with 70% for all-grain and adjust based on your measured results.

How does batch volume affect OG?

A smaller batch volume concentrates the same amount of sugar into less liquid, raising the OG. A larger batch dilutes it, lowering the OG. This is why hitting your target volume at the end of the boil is critical to achieving your target gravity.

Can I mix gallons and kilograms?

Yes. You can set batch volume in gallons or liters independently from grain weight in pounds or kilograms. The calculator converts all values to a consistent unit system internally before computing the OG.

Why does my measured OG differ from the estimate?

Differences arise from actual mash efficiency, wort absorption by grain (deadspace), evaporation rate during the boil, and temperature corrections on your hydrometer reading. This calculator gives an estimate — calibrate your efficiency figure over a few brew sessions for best accuracy.

Original Gravity Calculator

Name: Original Gravity Calculator
Availability: InStock
Author: Nham Vu

Enter your grain bill and batch volume to instantly calculate the estimated original gravity (OG) of your homebrew.

Batch Settings

Batch Size

Mash Efficiency (%)

Use 100% for malt extract

Grain Bill

Weight unit:

Fermentable

PPG

Weight

Estimated Original Gravity

1.000

—

1.000 1.120+

Water Barleywine

Brew Stats

Total Points

gravity pts

Est. ABV Range

assuming ~75% attenuation

Total Grain Weight

0 lb

all fermentables

Batch Volume

5 gal

post-boil target

OG Style Reference

Session / Light Beer 1.028 – 1.040

Standard Ale / Lager 1.040 – 1.055

Amber / Porter 1.055 – 1.070

IPA / Stout 1.060 – 1.085

Imperial / Barleywine 1.080 – 1.120+

Summary

Enter your grain bill and batch volume to instantly calculate the estimated original gravity (OG) of your homebrew.

How it works

Select your batch volume unit (gallons or liters) and enter the batch size.
Set your mash efficiency percentage (typically 65–75% for all-grain, 100% for liquid/dry malt extract).
Add each fermentable: choose a preset malt or enter a custom PPG value, then enter the weight in pounds or kilograms.
The calculator multiplies each grain's weight by its PPG and efficiency, sums all contributions, and divides by batch volume.
Your estimated Original Gravity (OG) is displayed in standard gravity units (e.g., 1.052).
Remove any grain row or adjust values to see the OG update in real time.

Use cases

Estimating OG before brew day to confirm you are hitting your target gravity.
Scaling a recipe up or down and recalculating the expected OG.
Comparing all-grain versus extract brewing efficiency impacts on OG.
Designing a new beer recipe and selecting grain combinations to reach a specific gravity range.
Teaching homebrewers how gravity points and extract efficiency work.
Double-checking a recipe from a book or blog before purchasing ingredients.
Planning a high-gravity or session beer and ensuring the grain bill fits the target.
Verifying that pre-boil gravity aligns with expected post-boil OG.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu