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Calcimator

Hay Box Cooker Calculator

Calculate heat retention time, temperature curve, and fuel savings for a hay box (retained heat) cooker based on pot size, insulation, and food mass.

Inputs

kg
cm
°C
m²·K/W
°C

Results

Time above 75 °C

17.7 hours

Time above 60 °C33 hours
Temperature after 2 hours97 °C
Temperature after 4 hours93 °C
Temperature after 8 hours88 °C
Fuel savings83%
Insulation volume needed48 liters
How to Use This Calculator
  1. Enter the mass of food plus liquid in the pot (kg) and pot diameter (cm).
  2. Set the starting temperature (typically boiling, 100 °C) and insulation R-value.
  3. Enter ambient room temperature.
  4. The calculator shows how long food stays above 75 °C (safe cooking zone) and above 60 °C, plus temperatures after 2, 4, and 8 hours.
  5. Bring food to a full boil on your stove, then transfer immediately to the insulated box for hands-free retained-heat cooking.
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