Rest Temperature
Calculate the hot water volume needed to raise mash temperature for step mashing.
Calculates hot water volume needed to raise mash temperature for step mashing.
How to Use
Enter the following values and the tool instantly calculates how much hot water to add. This is often boiling water, but you can enter another water temperature if that matches your process:
Current Temperature
The current mash temperature (measure after stirring well)
Target Temperature
The desired next rest temperature
Boil Temperature
The temperature of the water you will add (typically boiling)
Mash Water Volume
The volume of water currently in the mash
Grain Amount
The total weight of grain in the mash
Mash-Tun Heat Capacity
Your mash tun's heat capacity in L equivalent water volume (use the Mash-Tun Calibration tool to find this value)
Output
The tool displays the volume of hot water to add to reach your target temperature. The result accounts for heat absorbed by the grain and heat lost to the mash tun.
This is the same infusion-volume calculation Brewfather uses for calculated mash Infusion steps in the Recipe Designer, brew sheet, and Brew Tracker. In mash profiles, the infusion water temperature defaults to the boil temperature unless you enter a specific infusion water temperature on the step.
About Step Mashing
Step mashing involves resting the mash at different temperatures to activate specific enzymes and achieve desired wort characteristics. Adding boiling water is one method to raise the temperature between steps.
When to Use This Tool
Use for:
Multi-step mashes: Protein rest, saccharification steps
Mash out: Raising to 168°F to stop enzyme activity
Temperature corrections: Fixing low mash temperatures
Decoction alternative: Simpler than pulling grains
Common Mash Steps
Acid Rest
Temperature: 35-45°C (95-113°F)
Purpose: Lower pH, improve clarity
Duration: 10-20 minutes
Protein Rest
Temperature: 45-55°C (113-131°F)
Purpose: Break down proteins
Duration: 10-20 minutes
Good for: Wheat beers, pilsners
β-Glucan Rest
Temperature: 37-45°C (98-113°F)
Purpose: Break down gums
Duration: 10-20 minutes
Good for: High wheat/oat beers
Saccharification Rests
β-Amylase: 60-66°C (140-150°F) - fermentable sugars
α-Amylase: 66-71°C (150-160°F) - body/dextrins
Duration: 30-60 minutes each
Mash Out
Temperature: 76-77°C (168-170°F)
Purpose: Stop enzyme activity
Duration: 10 minutes
Benefits: Easier lautering
Calculation Factors
Heat Capacity
Water: 1.0 BTU/lb/°F
Grain: 0.38 BTU/lb/°F
Combined mash: ~0.2-0.3 BTU/lb/°F
Volume Limitations
Mash tun capacity
Each infusion thins mash
Plan steps accordingly
Example Calculations
Example 1: Protein to Saccharification
Current: 50°C (122°F) with 15 liters (4 gallons)
Target: 67°C (152°F)
Boiling water needed: ~9.5 liters (2.5 gallons)
Example 2: Saccharification to Mash Out
Current: 67°C (152°F) with 23 liters (6 gallons)
Target: 76°C (168°F)
Boiling water needed: ~7.5 liters (2 gallons)
Tips
Have boiling water ready before starting
Add water slowly while stirring
Check temperature frequently
Account for mash tun capacity limits
Advanced Techniques
Combined Step Mashing
Infusion + direct heat
Best of both methods
More flexibility
Requires right equipment
Reverse Step Mashing
Start high, cool down
Add cold water or grain
Less common method
Special applications
Using with Recipe Planning
Calculate water volumes needed for your mash schedule
Plan total water usage for multi-step mashes
Account for mash tun capacity limitations
The tool remembers your last entered values
Mash Schedule Planning
Two-Step Mash
Protein Rest: 50°C (122°F) for 15 min
Saccharification: 67°C (152°F) for 60 min
Three-Step Mash
Protein Rest: 50°C (122°F) for 15 min
β-Amylase: 63°C (145°F) for 30 min
α-Amylase: 70°C (158°F) for 30 min
Hochkurz Mash
Brief rest: 62°C (144°F) for 30 min
High rest: 72°C (162°F) for 30 min
Mash out: 76°C (168°F) for 10 min
Related docs
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