Rest Temperature

Calculate the boiling water volume needed to raise mash temperature for step mashing.

Calculates boiling water volume needed to raise mash temperature for step mashing.

How to Use

Enter the following values and the tool instantly calculates how much boiling water to add:

Input	Description
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 boiling water to add to reach your target temperature. The result accounts for heat absorbed by the grain and heat lost to the mash tun.

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

1. Protein Rest: 50°C (122°F) for 15 min

2. Saccharification: 67°C (152°F) for 60 min

Three-Step Mash

1. Protein Rest: 50°C (122°F) for 15 min

2. β-Amylase: 63°C (145°F) for 30 min

3. α-Amylase: 70°C (158°F) for 30 min

Hochkurz Mash

1. Brief rest: 62°C (144°F) for 30 min

2. High rest: 72°C (162°F) for 30 min

3. Mash out: 76°C (168°F) for 10 min

Related docs

• Mash Profiles

• Recipe Designer