# Mash-Tun Calibration

Determines your mash tun's heat retention characteristics for accurate strike temperature calculations.

## How to Calibrate

1. **Measure your ambient mash-tun temperature** -- the temperature of your empty, dry mash tun
2. **Prepare a carefully measured volume of hot water** and measure its temperature (this is the 0-minute reading)
3. **Add the hot water to the mash tun**, put the lid on, and take a new temperature reading after 5 minutes

### Inputs

The tool has four input fields:

| Input                            | Description                                                                      |
| -------------------------------- | -------------------------------------------------------------------------------- |
| **Mash-Tun Temperature**         | The ambient temperature of your empty mash tun before adding water               |
| **Hot Water Volume**             | The carefully measured volume of hot water you are adding                        |
| **Water Temperature, 0 minutes** | The temperature of the hot water just before you pour it in                      |
| **Water Temperature, 5 minutes** | The temperature of the water inside the mash tun after 5 minutes with the lid on |

### Output

The tool calculates your **Mash-Tun Heat Capacity** expressed in **L equivalent water volume**. Enter this value in your equipment profile to get more accurate strike water temperature calculations.

## Why Calibrate

Every mash tun loses heat differently based on:

* **Material**: Plastic, stainless steel, copper
* **Insulation**: Quality and thickness
* **Size**: Surface area to volume ratio
* **Environment**: Ambient temperature
* **Preheating**: How well you preheat

Calibration gives you a Mash-Tun Heat Capacity value specific to your equipment.

## Understanding the Results

### Mash-Tun Heat Capacity Values

* **0.0**: Perfectly preheated, no heat loss to the mash tun
* **0.1-0.2**: Well insulated or preheated
* **0.2-0.3**: Average homebrew setup
* **0.3-0.5**: Poor insulation or cold tun

### Using Your Result

* Enter the value in your equipment profile
* Use with the Strike Temperature Calculator for accurate predictions
* Consistent mash temperatures
* Better enzyme activity

## Improving Heat Retention

### Insulation Options

* **Reflective Bubble Wrap**: Cheap, effective
* **Foam Board**: Cut to fit
* **Sleeping Bag/Blankets**: Simple solution
* **Spray Foam**: Permanent option

### Preheating Methods

1. Fill with hot water 10 min before
2. Rinse with boiling water
3. Heat with strike water overage
4. Store in warm location

## Testing Variables

### What Affects Calibration

* **Ambient Temperature**: Test in brew conditions
* **Wind/Drafts**: Increase heat loss
* **Lid Seal**: Critical for retention
* **Mash Volume**: Fuller tun retains better

### When to Recalibrate

* New equipment
* Changed insulation
* Different season/location
* Inconsistent results

## Practical Examples

### Example 1: Cooler Mash Tun

* 38 liter (10 gallon) cooler
* No preheating
* 21°C (70°F) mash-tun temperature
* Result: 0.25 L equivalent water volume

### Example 2: Insulated Kettle

* Stainless kettle
* Wrapped insulation
* Preheated
* Result: 0.10 L equivalent water volume

## Using Your Calibration

### With Strike Calculator

* Enter the Mash-Tun Heat Capacity value in the Strike Temperature Calculator
* Set it to 0 if your mash tun is pre-heated
* More accurate temperature predictions
* Reduces mash temperature misses

### With Rest Temperature Calculator

* The same Mash-Tun Heat Capacity value is used when calculating boiling water additions for step mashing

## Tips

* Use consistent test methods
* Calibrate thermometer first
* Test in typical brewing conditions
* Average multiple test results

## Related docs

* [Equipment Profiles](https://docs.brewfather.app/profiles/equipment)
* [Setting Up Your Equipment Profile](https://docs.brewfather.app/getting-started/setting-up-your-equipment-profile)