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Calcimator

Parabolic Cooker Calculator

Calculate focal length, cooking power, concentration ratio, and boil time for a parabolic solar cooker based on dish size and reflectivity.

Inputs

ft
in
W/m²
in

Results

Cooking power at pot

933 W

≈ 16 laptops

Focal length46.9 cm
Concentration ratio36×
Max pot temperature500 °C
Time to boil 2 L water11.2 min
Dish area1.77 m²
f/D ratio0.31
How to Use This Calculator
  1. Enter the dish diameter and depth of your parabolic reflector.
  2. Set the reflector reflectivity (0–1) and current solar irradiance (W/m²).
  3. Enter the diameter of your cooking pot.
  4. The calculator outputs cooking power at the pot, focal length, concentration ratio, estimated max temperature, and time to boil 2 liters.
  5. Adjust dish diameter or reflectivity to explore trade-offs between power and construction complexity.

How the result changes with Dish diameter

Dish diameterCooking power at pot
0.77261 W
1.951,552 W
3.354,481 W
4.538,128 W

What each input means

Dish diameter
Outer diameter of the parabolic reflector. 1.0–1.8 m is common for cooking.
Dish depth
Depth of the parabolic dish from rim to vertex. Deeper = shorter focal length.
Reflector reflectivity
Reflectivity of the dish surface. Polished aluminum ≈ 0.85, mirror film ≈ 0.90, anodized ≈ 0.70.
Solar irradiance
Direct normal solar irradiance. Clear sky at noon ≈ 800–1000 W/m².
Pot diameter
Diameter of the dark/black cooking pot placed at the focal point.

What each result means

Cooking power at pot
Net thermal power concentrated on the cooking pot.
Focal length
Distance from dish vertex to focal point where the pot should be placed.
Concentration ratio
Ratio of dish area to pot area. Higher = more intense heat focus.
Max pot temperature
Theoretical maximum equilibrium temperature at the pot (radiative balance).
Time to boil 2 L water
Approximate time to bring 2 liters of water from 25 °C to boiling.
Dish area
Total reflective area of the parabolic dish.
f/D ratio
Focal-length-to-diameter ratio. 0.25–0.5 is typical for solar cookers.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Dish diameter = 1.5, Dish depth = 30, Reflector reflectivity = 0.85, Solar irradiance = 900 = 5 input(s) provided
  2. Calculate Cooking power at pot
    Cooking power at pot = collectedPowerW * interceptFactor * potAbsorptance
    933 = 933
  3. Calculate Focal length
    Focal length = focalLengthM * 100
    46.9 = 46.9
  4. Calculate Concentration ratio
    Concentration ratio = dishAreaM2 / potAreaM2
    36 = 36

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