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Convection Heat Transfer Calculator

Calculate convective heat transfer from a surface using Newton’s law of cooling.

About Convection Heat Transfer Calculator

The convective coefficient spans four orders of magnitude between natural convection in air and boiling, which is why it dominates any thermal design. Heat flow is otherwise simply proportional to area and temperature difference. Adding a fan can raise the coefficient tenfold, which is usually far cheaper than increasing surface area by the same factor.

Formula

Convection Heat Transfer

Q̇ = h A (T_s − T_∞)

h
Convective heat transfer coefficient, strongly dependent on fluid and flow
T_s − T_∞
Surface to bulk fluid temperature difference

Worked example

With the default values below, Convection Heat Transfer Calculator returns Convective Heat Loss of 3,000.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Convective heat transfer coefficientminimum 0.01 W/m2 K
25 W/m2 K
Surface areaminimum 0 m2
2 m2
Surface temperatureminimum -273 C
80 C
Surrounding fluid temperatureminimum -273 C
20 C

Results

Convective Heat Loss
3,000.000 W
Temperature Difference
60.00 K
Heat Flux
1,500.000 W/m2
Annual Energy Lost at Continuous Duty
26,280.0 kWh
Convection Regime
Forced convection in air

Step by step

  1. 1Values used
  2. 2Convection Heat Transfer
  3. 3Convective Heat Loss= 3,000.000 W
  4. 4Temperature Difference= 60.00 K
  5. 5Heat Flux= 1,500.000 W/m2
  6. 6Annual Energy Lost at Continuous Duty= 26,280.0 kWh
  7. 7Convection Regime= Forced convection in air

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Convection Heat Transfer calculated?

Q̇ = h A (T_s − T_∞) The convective coefficient spans four orders of magnitude between natural convection in air and boiling, which is why it dominates any thermal design. Heat flow is otherwise simply proportional to area and temperature difference.

Why does Convection Heat Transfer matter?

Adding a fan can raise the coefficient tenfold, which is usually far cheaper than increasing surface area by the same factor.

What values do I need to enter?

This calculator takes 4 inputs: Convective heat transfer coefficient, Surface area, Surface temperature, Surrounding fluid temperature. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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