Dehydration Time Calculator Formula

Understand the math behind the dehydration time calculator. Each variable explained with a worked example.

Use the Dehydration Time Calculator

Formulas Used

Base Drying Time

base_hours = food_type

Estimated Drying Time

adjusted_hours = round(food_type * (thickness / 5) * (135 / temp) * humidity)

Minimum (check at)

min_hours = round(food_type * (thickness / 5) * (135 / temp) * humidity * 0.7)

Maximum

max_hours = round(food_type * (thickness / 5) * (135 / temp) * humidity * 1.3)

Variables

VariableDescriptionDefault
food_typeFood Category8
thicknessSlice Thickness(mm)5
tempDehydrator Temperature(°F)135
humidityAmbient Humidity1

How It Works

How to Estimate Dehydration Time

Formula

Time = Base Hours x (Thickness / 5 mm) x (135 / Temp) x Humidity Factor

Thicker slices take proportionally longer. Higher temperatures speed drying. High humidity slows the process because the air can absorb less moisture.

Recommended Temperatures

  • Herbs: 95-110°F (preserve volatile oils)
  • Fruits: 125-135°F
  • Vegetables: 125-140°F
  • Jerky/Meat: 155-165°F (must reach 160°F internal for food safety)

    • Doneness Tests

    Fruits should be pliable but not sticky. Vegetables should be brittle. Jerky should bend and crack but not snap.

    Worked Example

    Apple slices 5 mm thick at 135°F with moderate humidity.

    food_type = 8thickness = 5temp = 135humidity = 1
    1. 01Base time for fruit = 8 hours
    2. 02Thickness factor = 5/5 = 1
    3. 03Temperature factor = 135/135 = 1
    4. 04Humidity factor = 1
    5. 05Estimated = 8 x 1 x 1 x 1 = 8 hours
    6. 06Check at 6 hours, may take up to 10 hours.

    Ready to run the numbers?

    Open Dehydration Time Calculator