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Homebrewer, eternal E'Lir, Physics, and Math Student.

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Hoping to make this easier for new brewers, and wanted to clarify a couple things about my Calculator which can be found at the top of this page.

Going from Top to bottom, and left to right.

Default BIAB values for my equipment. Default BIAB values for my equipment.

Enter your details

Batch Size Gallons

This is the volume into the fermenter, and will equal Post boil volume once chilled.

Grain Bill in Lb

Total weight of all grains, exclude any additional sugar adjuncts (table, sucrose, corn, belgian candy etc) added during the boil

Hop Bill in Oz

For now this is the total amount of all hops in any form. Pellet, dry, or wet, doesn’t matter. If I can find the requisite data, I would like to seperate these as they absorb different amounts of water.

Length of Boil in Min(s)

Self evident.

Boil-Off Rate (Gal/Hr)

Self Evident. I highly recommend you do a test boil, measuring your starting water volume and temp, and your final water volume and temp. I’m going to make another little calculator to figure out your boil off rate.

Grain Temp in Fahrenheit for Imperial, and Celsius for Metric

This is important, I know I’ve been guilty of not checking it but it can change your mash temp about a half degree.

Mash Temp in Fahrenheit for Imperial, and Celsius for Metric

This is your mash temp, after dough in, and mixing thoroughly. If different locations have different temps, you haven’t stirred enough.

Sparging Volume in Gallons

Amount of water you’re sparging with, at 68F, This can either be batch sparge, dunk sparge, or pour over.

How Big is your Kettle/Mashtun? (Gallons)

Maximum volume of your mash tun if mash in a bag, or Brew kettle if BIAB.

How Wide is your Kettle/Mashtun? (Inches)

Diameter of your brew kettle, used for determining water volume heights.

Trub Loss (Gallons)

Trub loss is currently trub loss from brew kettle after chilling, and before racking to fermenter.

Grain Absorption (Gallons/Lb)

How much water your grain absorps, and does not release from squeeze/sparging. Hard Squeeze is the default, you may get very close if allowed to drain naturally and suspended. If allowing to drain in a bucket with no self pressure from suspending the bag I recommend 0.1 If doing traditional mashing in a cooler, and not squeezing or allowing the bag to drain I recommend 0.125.

Hop Absorption (Gallons/oz)

Amount of wort your hops absorb. This absorption rate was cited for dry leaf hops, I know pellets and wet will be slightly different, but haven’t found a credible source for them yet.

General Results

Total water needed

8.50 Gallons 18.114 Inches high This is the total amount of water used to end at desired batch size into fermenter. Assumed at 68F

Strike temp

163.64 F Calculated Strike temp for Strike volume.

Mash Thickness

1.70 Quarts/Lb Calculated mash thickness from grain bill and strike volume @ mash temp.

Total volume loss

3.00 Gallons

Total amount of wort/water lost, from trub, grain absorption, and hop absorption.

Gallon height

2.1303 Inches high Height of each gallon, assuming straight walled perfect cylinder.

Minimum Sparging Volume

2.83 Gallons Recommended minimum sparging volume given pot size and mash volume.

Water Volumes and Heights

Water volume at 68F

8.50 Gallons 18.114 Inches high Total water needed, calibrated for 68F and calculated height.

Strike water volume (temp. adjusted at strike temp)

8.54 Gallons 18.203 Inches high Strike water needed, calibrated for strike temp and calculated height.

Volume of mash with grains (temp. adjusted at mash temp)

10.3 Gallons 21.985 Inches high Mash water needed and grain volume after dough in, calibrated for strike temp and calculated height.

Pre boil (temp. adjusted at 212F)

7.21 Gallons 15.350 Inches high Desired pre boil volume, at boil temp. If different and you trust your boil off rate, boil down to this volume.

Post boil (temp. adjusted at 212F)

5.74 Gallons 12.230 Inches high Post boil volume, at boil temp, This is about 4.4% higher than desired batch size due to thermal expansion at boil.

Alternative calculator form for entering mash thickness instead of sparging volume is the exact same terms besides those two variables.

Mash Thickness (Qt/Lb)

Desired Mash thickness after dough in.dangers from happening.

Default BIAB values for my equipment.

Default BIAB values for my equipment.

Maximum Mash Thickness (3.35 Qt/Lb)

Maximum Mash thickness determined from your grain bill, batch size, losses, and pot size. Would recommend keeping Mash Volume .5 gallons below Pot size, for ease of dough in, stirring, and to keep any potential