Physics

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Heat Transfer Coefficient Calculator.

Calculate an overall heat-transfer coefficient from heat rate, area, and temperature difference.

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Heat-transfer coefficient: 5

Heat-transfer coefficient

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Educational SI models with assumptions stated in each description; verify engineering decisions independently.

Use Cases

Engineering design of heat exchangers

Determine the required heat transfer coefficient for a given heat load, surface area, and temperature difference to size or evaluate heat exchangers.

Example: A heat exchanger transfers 5000 W over 2 m² with a 25 K difference, giving U = 100 W/(m²·K).

Educational physics problems

Solve textbook problems involving convective or overall heat transfer by calculating the coefficient from given parameters.

Example: Given Q = 1200 W, A = 0.5 m², ΔT = 40 K, find U = 60 W/(m²·K).

Frequently Asked Questions

What is the heat transfer coefficient?
The heat transfer coefficient (U) measures how effectively heat is transferred between a surface and a fluid, or between two fluids separated by a wall. It is defined as the heat rate per unit area per unit temperature difference. In this calculator, U = heat rate / (area × temperature difference).
How do I use this calculator?
Enter the heat-transfer rate in watts (W), the area in square meters (m²), and the temperature difference in kelvin (K). The calculator will compute the overall heat-transfer coefficient in W/(m²·K). Ensure all inputs are positive and in the correct units.
What units should I use?
Use watts for heat-transfer rate, square meters for area, and kelvin for temperature difference. The result will be in watts per square meter per kelvin (W/(m²·K)). If your temperature difference is in Celsius, note that a difference of 1°C equals 1 K, so you can use the same numeric value.

Tips & Common Mistakes

Tips

  • Ensure the temperature difference is in kelvin (K) or Celsius (since a difference of 1°C = 1 K).
  • Use consistent units: watts, square meters, and kelvin for accurate results.
  • Double-check that the area is the heat transfer surface area, not the cross-sectional area.
  • For multiple layers, the overall coefficient accounts for all resistances; this calculator gives the overall value.

Common Mistakes to Avoid

  • Using Celsius absolute temperatures instead of temperature difference; only the difference matters.
  • Entering area in cm² or mm² without converting to m², leading to incorrect results.
  • Confusing heat-transfer rate (W) with heat flux (W/m²); this calculator requires the total rate.

Last updated: August 13, 2026