Calculator Form
Example Data Table
| Batch Size | Grain | Mash Ratio | Boil-Off | Boil Time | Estimated Total Water |
|---|---|---|---|---|---|
| 19 L | 5 kg | 2.7 L/kg | 3.5 L/hr | 60 min | 26.67 L |
| 23 L | 6 kg | 2.8 L/kg | 4 L/hr | 75 min | 32.75 L |
| 10 L | 2.8 kg | 3 L/kg | 2 L/hr | 45 min | 14.42 L |
Formula Used
Boil Loss = Boil-Off Rate × Boil Time / 60
Cold Post-Boil Need = Batch Size + Trub Loss + Kettle Deadspace - Top-Up Water
Hot Post-Boil Need = Cold Post-Boil Need ÷ (1 - Shrinkage Percentage)
Pre-Boil Volume = Hot Post-Boil Need + Boil Loss
Strike Water = Grain Weight × Mash Thickness
Absorption Loss = Grain Weight × Grain Absorption
First Runnings = Strike Water - Absorption Loss - Mash Tun Deadspace
Sparge Water = Pre-Boil Volume - First Runnings
Total Brewing Water = Strike Water + Sparge Water
How to Use This Calculator
Enter the final batch size you want to collect.
Add the boil time and your hourly boil-off rate.
Enter the full grain bill weight.
Add your mash thickness in liters per kilogram.
Use your system losses for deadspace, trub, and absorption.
Press the calculate button.
Review the strike water, sparge water, and total water output.
Download the result as CSV or PDF for brew day records.
Brewing Water Volume Planning Guide
Why Water Volume Matters
Water volume controls mash flow, extraction, boil strength, and final yield. Small errors can shift gravity and recipe balance. A planned volume also reduces waste. It helps the brewer repeat a successful batch. Good water planning starts before grain is crushed. Each brewing system has unique losses. The calculator allows those losses to be included.
Mash and Strike Water
Strike water is the water mixed with crushed grain. It sets the mash thickness. A thin mash can improve mixing. A thick mash may save space. Most brewers choose a steady ratio. The ratio should match the tun size. Grain absorbs water during the mash. That absorbed water does not reach the kettle. This tool subtracts that loss from first runnings.
Boil and Cooling Losses
Wort volume falls during the boil. Heat drives evaporation from the kettle. A wider kettle may lose more water. A stronger boil may also increase loss. Cooling creates shrinkage too. Hot wort occupies more volume than cooled wort. The calculator adjusts the hot target so the cooled target stays accurate.
Sparge Water Control
Sparge water rinses sugars from the grain bed. It also builds the required pre-boil level. Too little sparge water lowers kettle volume. Too much can dilute gravity. The tool estimates sparge volume after strike water, absorption, and deadspace are considered. This makes the pre-boil number easier to reach.
Better Batch Consistency
Record each result after brewing. Compare the estimate with actual measured volumes. Update boil-off, absorption, and deadspace values when needed. Over time, the calculator becomes more accurate for your equipment. Consistent volume planning supports consistent original gravity. It also improves fermentation volume and packaging yield.
FAQs
1. What is brewing water volume?
It is the total water needed for mashing, sparging, boiling, cooling, and transferring wort into the fermenter.
2. What is strike water?
Strike water is the hot water mixed with grain at mash-in. It creates the mash and starts starch conversion.
3. What is sparge water?
Sparge water rinses remaining sugars from the grain bed. It helps reach the planned pre-boil kettle volume.
4. Why include grain absorption?
Grain holds water after draining. Including absorption gives a more realistic estimate of first runnings and sparge needs.
5. Why does cooling shrinkage matter?
Hot wort contracts as it cools. A shrinkage adjustment helps match hot kettle volume with the final cooled target.
6. Can I use gallons instead of liters?
Yes. Use one unit consistently across every field. The math works when all volume inputs use the same unit.
7. What is kettle deadspace?
Kettle deadspace is wort left behind below the drain point or trapped with sediment after transfer.
8. How can I improve accuracy?
Measure real losses during brew day. Update boil-off rate, deadspace, and absorption values after each batch.