Brewing Tools & Formulas

Screwy Calc (at right) uses the Original Gravity (OG) and Final Gravity (FG) temperatures to calculate the residual CO2 volumes of your beer.

  Specific gravity temperature corrections are also applied to calculations of calories, carbohydrates, attentuation, extract, Plato and yeast pitching rates.

  Yeast pitching rates are calculated in billons of cells. The formula uses adjusted final gravity Plato and wort size in gallons to determine how much yeast should pitched for either Ale and Lager type beers.

Screwy's Brewing Calculators

   Alcohol Content Calculator
   American/Metric Calculator
   Batch Bottle Sizing Calculator
   Bottle Priming Calculator
   Cylinder Volume Calculator
   ezBIAB Calculator©
   Force Carbonation Calculator
   Grain Bill Percentage Calculator
   Hop Bitterness Calculator
   Hop Bitterness, Flavor And Aroma Chart
   Hop Bitterness Balance Calculator
   Mash Water Volume Calculator
   Rest Temperature Calculator
   Standard Reference Method Color Chart
   Strike Temperature Calculator

qBrew - Homebrewers Recipe Calculator
  This free beer recipe calculator is intuitive, easy to install and fun to use.
Use it to automatically calculate the gravity, color and bitterness of your own recipes.
Download it today and also get Screwy's database including the latest Mr. Beer ingredients.

   qBrew - Homebrewers Recipe Calculator

Alcohol Content

Enter the full specific gravity (SG) readings including the decimal point and the percentage of alcohol will be calculated when you click on the submit button.
(Example: 1.050)

(OG) - Original Gravity

The first reading is of the beer in your fermenter, before you start the fermentation process. Take this reading when all the water has been added and you are ready to pitch the yeast. Pour a sample out of the tap into a test flask and set it aside to cool to about 70F (20C).

(FG) - Final Gravity
The second reading is of the finished beer. This is taken when you are ready to bottle your beer and this too should be about 70F (20C).

Residual CO2
 A certain amount of Residual CO2 remains in the beer after the fermentation has completed, depending on the fermentation temperature. An ale fermented at 65°F will have 0.9 volumes of residual CO2 while a lager fermented at 50°F will have 1.2 volumes. To get the same carbonation in these two beers would require different amounts of priming sugar.

Too much priming sugar or bottling a batch of beer that is not done fermenting can cause exploding bottles so don't carbonate bottles to higher pressures than the beer that came in them and exercise caution when entering numbers and using the results from this calculator.

Please note that DME varies in its fermentability, a few example brand names are provided with their approximate apparent attenuation (AA) values. Typically, DME has an AA of 70% to 75%, with the notable exception of Laaglander brand at 55%

The apparent attenuation you will get on a given batch depends on a number of factors, including the types of grains/extracts used, mash temperature (if brewing all-grain), and the strain of yeast. Typically, apparent attenuation will range from 65 to 80%. Beers with a lower apparent attenuation will be sweeter, fuller-bodied, and lower in alcohol. Higher apparent attenuation will result in a drier, thinner, higher alcohol brew.


Alcohol Content Calculator


Enter your original and final hydrometer readings below, then click 'Calculate'


Original Gravity (OG)

Final Gravity (FG)
Apparent attenuation
Real attenuation
Freezing point degrees
Calorie content for = calories



Forced Carbonation Calculator

Using the 'set and forget' method of forced carbonation is the easiest and most accurate way to force carbonate kegged beer. Simply hold the temperature of your beer constant (34-38°F) then set your CO2 regulator pressure and gas your beer for a week. This will give you the consistent carbonation levels that are necessary for balancing your draft lines and taps to produce great pours.
Enter the temperature of the beer to carbonate and your target Co2 volume.
Temperature of beer [°F]
Target CO2 volumes
Regulator pressure [psi]



Bottle Priming Calculator

Naturally carbonating your beer should be done soon after your beer has reached it's final gravity, which is based on getting the same hydrometer reading two or more days apart. Adding the right amount of fermentable sugar to the beer will provide the yeast with just enough food for them to create the right amount of CO2 needed to hit your carbonation level. Remember when using the calculator be sure to input the 'warmest' temperature the beer has reached prior to bottling it, colder beer holds CO2 in solution better than warmer beer which allows CO2 to escape easier.
Enter your target CO2 volume, beer temperature, beer volume and priming ingredient.
Desired CO2 volumes 
Beer temperature  degrees
Beer volume 
Priming ingredient
Residual CO2  volumes
Sugar needed   

** A reference temperature of 0°C is used to measure the volume of CO2 **

This information is provided 'as is', the author assumes no liability for the use of the results
from this calculator. Always take care when entering data and/or using the results of your calculations.

Beer Carbonation Guide By Style

StylesCO2 Volumes
Barley Wine
   Barley Wine  1.3 to 2.3
Belgian Specialty
   Flanders Brown  1.9 to 2.5
   Dubbel  1.3 to 2.3
   Trippel  1.9 to 2.4
   Belgian Ale  1.9 to 2.5
   Belgian Strong Ale  1.9 to 2.5
   White  2.1 to 2.6
   Lambic Gueuze  3.0 to 4.5
   Lambic Faro 
   Lambic Fruit  2.6 to 4.5
English Bitter
   English Ordinary  0.75 to 1.3
   English Special  0.75 to 1.3
   English Extra Special  0.75 to 1.3
Scottish Ale
   Scottish Light  0.75 to 1.3
   Scottish Heavy  0.75 to 1.3
   Scottish Export  0.75 to 1.3
Pale Ale
   Classic English Pale Ale  1.5 to 2.3
   India Pale Ale  1.5 to 2.3
   American Style Pale Ale  2.26 to 2.78
English & Scottish Strong Ale
   English Old Ale/Strong Ale  1.5 to 2.3
   Strong Scotch Ale  1.5 to 2.3
Brown Ale
    English Brown Ale  1.5 to 2.3
    English Mild Ale  1.3 to 2.0
    American Brown Ale  1.5 to 2.5
    Robust Porter  1.8 to 2.5
    Brown Porter  1.7 to 2.5
    Classic Dry Irish  1.6 to 2.0
    Foreign Style  2.3 to 2.6
    Sweet Stout  2.0 to 2.4
    Imperial Stout  1.5 tp 2.3
    Traditional German Dark  2.2 to 2.7
    Helles Bock  2.16 to 2.73
    Doppelbock  2.26 to 2.62
    Eisbock  2.37
Bavarian Dark
    Munich Dunkel  2.21 to 2.66
    Schwarzbier  2.2 to 2.6
American Dark
    American Dark  2.5 to 2.7
    Dortmund/Export  2.57
Munich Helles
    Munich Helles  2.26 to 2.68
Classic Pilsener
    German Pilsener  2.52
    Bohemian Pilsener  2.3 to 2.5
American Light Lager
    Diet/"Lite"  2.57
    American Standard  2.57
    American Premium  2.57 to 2.73
    Dry  2.6 to 2.7
    Vienna  2.4 to 2.6
    Oktoberfest/Marzen  2.57 to 2.73
German Ale
    Dusseldorf-style Altbier  2.16 to 3.09
    Kolsch  2.42 to 2.73
Cream Ale
    Cream Ale  2.6 to 2.7
American Wheat
    American Wheat Beer  2.3 to 2.6
Smoked Beer
    Bamberg-style Rauchbier  2.16 to 2.57
California Common
    California Common Beer  2.4 to 2.8
German Wheat Beer
    Berliner Weisse  3.45
    German-style Weizen (Weissbier)  3.6 to 4.48
    German-style Dunkelweizen  3.6 to 4.48
    German-style Weizenbock  3.71 to 4.74

Batch Bottle Sizing Calculator

Use this calculator to figure out how to bottle beer in the exact combination you desire.

A 5 gallon batch of beer fills up:
  • 54 - 12 ounce long necks
  • 38 - 16.9 ounce half liters
  • 30 - 22 ounce bombers
  • 10 - 64 ounce growlers
  • 4 - 5 liter mini kegs
Gallons to package:
Ounces to package:
Units Quantity Amount Bottled
Euro 330ml 11.2 oz
Long Neck 12 oz
Grolsh 15.2 oz
Half Liter 16.9 oz
Bomber 22 oz
Wine 25.4 oz
Grenade 32 oz
Growler 64 oz
Gallon Jug 128 oz
5 Liter Mini-Keg 169 oz
Batch Size:

Enter your hop additions on separate lines including.....

Wort gravity, Volume, Alpha Acid, Ounces and Boil Time then click 'Calculate'.

HOP Bitterness Calculator

** For Mr. Beer HME enter an SG of 1.036, 1.0 Ounce and a Boil Time of 5 minutes. **
Wort Specific Gravity (during boil)  Final Volume (gal)
AdditionAlpha Acid %Oz. AddedBoil Mins.Utilization %IBUs
Total IBUs

 Mr. Beer Hopped Malt Extract (HME) Hop Guide
 Mr. Beer (HME) Example Input: SG = 1.036 - 1 Oz. - 5 Minute Boil
    Hopped Malt Extract Alpha Acid %
    American Devil IPA  16.3
    Bewitched Red Ale  7
    Black Tower Porter  5.7
    Classic American Blonde  10.2
    Cowboy Golden Lager  10.2
    Englishman's Nut-Brown Ale  12.4
    Grand Bohemian Czech Pilsner  5.1
    High Country Canadian Draft  12.4
    Linebacker Bock  12.4
    Octoberfest Vienna Lager  13.1
    Pilothouse Pilsner  5.1
    St. Patrick's Irish Stout  18.1
    Sticky Wicket Oatmeal Stout  8
    West Coast Pale Ale  12.4
    Whispering Wheat Weizenbier  10.2
    Witty Monk Witbier  5.1

Bitterness Balance Calculator

The BJCP Style Guidelines state the desired number of International Bittering Units (IBU) that are needed to obtain a balance between hopped bitterness and malt sweetness in a hopped beer style. Beers that don't taste sweet or bitter are considered to be balanced, although individual beer drinkers may percieve this differently. The formula used in this calculator returns the desired IBUs needed to keep a hopped beer style in balance using the formulas published on the Beer Color and Brewer's Math website.

The formula takes into consideration the beer's original gravity, actual attenuation and bittering level but does not take into account phenol, ester or other complexities. The beer drinker should use the desired IBUs as a reference point and decide for themselves what they consider to be balanced.
Original Gravity BJCP Style Guidelines   
Apparent Attenuation
International Bittering Units (IBU)   

Mash Calculators

 Mash temperatures play a significant role in the creation of your wort and the beer that is made from it. Many brewing publications agree that the optimum temperature range for an infusion mash ranges from 147°F to 155°F. A mash done at the lower end of this range will produce a well attenuated lower gravity beer and a mash done at the higher end of the range will produce a dextrinous higher gravity beer.
 It is important to hit your required mash temperature as early as possible when adding your hot water to the grains. Within the first 5 minutes of the mash is when the enzymes are the most active and when they will produce the most fermentable sugars. Needless to say if you unintentionally go in too hot with your strike water you will overshoot your final gravity so it's important to heat your strike water correctly at the very start of the mash.
 The formulas used in the calculators below are based on the earlier work of Ken Schwartz as published on Green Bay Rackers and have been modified for use on this site. The calculators have been tested but you should note that they are meant to provide you with approximate recommendations as they do not take into account differences in your equiptment or brewing process. Use care when entering your input data, avoid typos as the calculators will crunch them as well as correct input data.
 To get the most from your calculations use the output values as a starting point and be sure to write down your actual results as they pertain to your brewing equipment. Using your notes as a reference when calculating your next mash will help you fine tune differences in the surface area, volume, temperature and heat loss of your current equiptment.

Strike Temperature Calculator
 To calculate the Required Strike Temperature you will need to heat your water to in order to hit your Target Strike Temperature enter the following information.
 First enter your Mash Thickness, the ratio of sparge water to used in the mash. (Example: 1.25 qts. water to 1 lb. grain)
 Next enter your Target Strike Temperature, the mash temperature you wish to maintain inside your mash tun. (Example: 153 F)
 Then enter the Grain Temperature, the temperature of the grains inside your mash tun before adding any water. (Example: 70 F)
Mash ThicknessQt/Lb or L/kg
Target Strike TemperatureDegrees
Grain TemperatureDegrees
Required Strike TemperatureDegrees
Units of Measurement:AmericanMetric

Rest Calculator

 To calculate the Amount Of Boiling Water you will need to raise your mash water to in order to hit your Target Strike Temperature enter the following information.
 First enter your Weight of Grains, the dry wieght of the grains in the tun. (Example: 10 lbs. grain)
 First enter your Mash Thickness, the ratio of sparge water to used in the mash. (Example: 1.25 qts. water to 1 lb. grain)
 Next enter your Current Mash Temperature, the mash temperature you wish to maintain inside your mash tun. (Example: 135 F)
 Next enter your Target Strike Temperature, the mash temperature you wish to maintain inside your mash tun. (Example: 153 F)
 Then enter the Grain Temperature, the temperature of the grains inside your mash tun before adding any water. (Example: 70 F)
Weight of GrainsLb or kg
Mash Thickness Qt/Lb or L/kg
Current Mash Temperature Degrees
Target Strike Temperature Degrees
Amount Of Boiling WaterQts or Liters
Units of Measurement: American Metric

Mash Water Volume Calculator
 To calculate the Amount Of Space your mash will require, including grains and water, enter the following information.
 First enter your Weight of Grains, the dry wieght of the grains in the tun. (Example: 10 lbs. grain)
 First enter your Mash Thickness, the ratio of sparge water to used in the mash. (Example: 1.25 qts. water to 1 lb. grain)
Weight of GrainsLb or kg
Mash ThicknessQt/Lb or L/kg
Amount Of SpaceGallons or Liters
Units of Measurement: American Metric

Calculate The Percentage Of Grains

Enter the Percentage of grains, in pounds, ounces or grams, to calculate the total weight.
The default weight of 10 pounds of grains is used in the example below.

No.Grain BillPercentageUnitAmount
1 %
2 %
4 %
TOTAL: 0.00%
Size Unit:


Calculate The Volume Of A Cylinder

Enter the Radius and Height of the cylinder, in feet or inches, to calculate it's volume.
The volume of a hydrometer tube 10 inches tall and 1 inch in diameter is calculated below.

Volume Gallons

American/Metric Conversion
Units To Convert
°F to °C    °C to °F
Lb to kg    kg to Lb
Qt to L      L to Qt
Oz to g     g to Oz
Converted Units

TheStandard Reference Method or SRM Color Chart

Note that SRM is a measure of beer color density more than hue/tint.  Keep this in mind when attempting to use only SRM numbers when describing beers.  Within these Guidelines, beer color descriptors generally follow this mapping to SRM values.

Hop Bitterness, Flavor, Aroma Chart

Boiling hops for more than 60 minutes doesn't contribute much more bitterness since most of the hop oil isomerization happens earlier in the boil .  Maximize hop flavor by boiling them for no more than 20 minutes and to get the most hop aroma boil them for 7 minutes or less. Additional ways of increasing hop aroma is to add them at the very end of the boil and leave them in the kettle as the wort cools. You can also add aroma hops to the fermentor about 4 days after pitching your yeast or 14 days before bottling or kegging.