Formulas

Temperature conversions

Fahrenheit to Celsius

C = (F - 32.0) / 1.8

Celsius to Fahrenheit

F = (C * 1.8) + 32.0

Specific Gravity temperature corrections

Relative to 15C (59F) single range

All temperatures are in expressed in degrees F.

          correction = 1.313454 - 0.132674*F + 0.002057793*F*F - 0.000002627634*F*F*F

          SG_corrected = SG + (correction * 0.001)

Relative to 15C (59F) and divided into 3 ranges

All temperatures are in expressed in degrees C.

For temperatures less than 3.98 C:

          correction = -0.000032692*C - 0.000740644

For temperatures less than 50.0 C and greater than or equal to 3.98 C:

          correction = -0.0008031922 - 0.0000473773*C + 0.000007231263*C*C - 0.00000003078278*C*C*C

For temperatures greater than or equal to 50.0 C:

          correction = -0.005431719 + 0.0001963596*C + 0.000002661056*C*C

          SG_corrected = SG + correction

Weight conversions

Pounds to kilograms

Kgs = lbs * 0.453592

Kilograms to pounds

lbs = kgs * 2.204623

Volume conversions

Gallons to liters

liters = gals * 3.785412

Liters to gallons

gallons = liters * 0.264272

Quarts to liters

liters = qts * 0.946353

Liters to quarts

quarts = liters * 1.056688

Step mash temperature additions

Here we find the volume of a water addition to raise/lower the temperature of a mash

Vadd = (Vmash * (TCm - TFm)) / (TFm - Ta)

          where:
                   Vadd  = volume of the water addition
                   Vmash = current volume of the mash
                   TCm   = current temperature of the mash
                   TFm   = final (target) temperature of the mash
                   Ta    = temperature of the water addition

SG to plato

Reference: Manning, M.P., Understanding Specific Gravity and Extract, Brewing Techniques, 1,3:30-35 (1993)

Plato = -676.67 + 1286.4*SG - 800.47*SG*SG + 190.74*SG*SG*SG

Dilutions

New volume from current volume, current SG, and target SG

Vnew = ((SGc - 1.0)/(SGt - 1.0)) * Vcur

          where:
                   Vcur = current volume
                   SGc  = current SG
                   SGt  = target SG

New SG from current SG, current volume, and target volume

SGnew = ((SGc - 1.0) * (Vcur / Vtar)) + 1.0

          where:
                   SGc  = current SG
                   Vcur = current volume
                   Vtar = target volume

Alcohol content

Alcohol by weight according to George Fix:

Abw = (OE - RE) / (2.0665 - (0.010665 * OE))

          where:
                   OE = Original extract in degrees Plato
                   RE = (0.1808 * OE) + (0.8192 * AE)

                              where:
                                       AE = Final (apparent) extract in degrees Plato

Use SG to Plato conversion above to find OE and AE from specific gravity

Alcohol by weight according to A.J. de Lange:

Abw = (PO - PF) * BF

          where:
                   PO = Original degrees Plato
                   PF = Finished degrees Plato
                   BF = Ballings factor = 0.39661 + (0.0017091*Plato) + (0.000010788*Plato*Plato)

Use SG to Plato conversion above to find PO and PF from specific gravity

Calories in 12 ounces of beer

Calories from alcohol:

Ca = (1881.22 * FSG) * ((OSG - FSG)/(1.775 - OSG))

          where:
                   OSG = Original Specific Gravity
                   FSG = Final Specific Gravity

Calories from extract:

Ce = 3550.0 * FSG * ((0.1808 * OSG) + (0.8192 * FSG) - 1.0004)

          where:
                   OSG = Original Specific Gravity
                   FSG = Final Specific Gravity

Strike temperature

Refractometer

Brix to Specific Gravity

Formula was derived from the 69th edition (1988-1989) of the CRC Handbook of 
Chemistry and Physics, "Concentrative Properties of Aqueous Solutions:
Conversion Tables", Table 88 Sucrose

MathCAD was used to curvefit the data for Degrees Brix @ 20 C (% sucrose 
by weight) and specific gravity @ 15 C

SG = 1.000898 + 0.003859118*B + 0.00001370735*B*B + 0.00000003742517*B*B*B

          where:

                   B  = measured refractivity in Brix
                   SG = calculated specific gravity at 15 C

Final Specific Gravity from original and final Brix

SG = 1.001843 - 0.002318474*OB - 0.000007775*OB*OB - 0.000000034*OB*OB*OB + 0.00574*FB + 0.00003344*FB*FB + 0.000000086*FB*FB*FB

          where:

                   SG = estimated specific gravity of the sample
                   OB = Original Brix
                   FB = Final Brix

Brix to Index of Refraction

RI = 1.33302 + 0.001427193*B + 0.000005791157*B*B

          where:

                   B  = measured refractivity in Brix
                   RI = calculated Refractive Index

Alcohol by weight content from Final SG and Final Brix

RI  = 1.33302 + 0.001427193*FB + 0.000005791157*FB*FB
ABW = 1017.5596 - (277.4*SG) + RI*((937.8135*RI) - 1805.1228)

          where:
                   FB = Final Brix
                   RI = calculated Refractive Index
                   SG = Final SG

Last modified: Mon Mar 25 12:18:41 PST 2002