Heat Transfer Coefficient Calculator Suite

Heat Transfer Coefficient Calculator – Conduction, Convection, Radiation & Overall U

Heat transfer coefficients are central to thermal analysis in building design, mechanical engineering, process equipment, electronics cooling and many other applications. This Heat Transfer Coefficient Calculator collects the most common steady-state formulas in one place and lets you work in Celsius, Fahrenheit or Kelvin.

Instead of manually juggling k, h, U, thermal resistance and Q = U·A·ΔT, you can move through four dedicated modes: conduction, convection, radiation and overall heat transfer. Each tab focuses on a standardationship and reports both intermediate and final values so you can follow the physics behind the numbers.

How the Heat Transfer Calculator Is Organized

The suite is split into four modes that match typical engineering questions:

• Conduction: Thermal conductivity, thickness, U-value, R-value and heat flow through a solid layer.
• Convection: Convection coefficient h from measured or assumed heat flux and temperature difference.
• Radiation: Effective radiation coefficient h_r and radiative heat flux between a surface and surroundings.
• Overall: Combined conduction and convection in series to compute overall U and Q through a wall or surface system.

Mode 1 – Conduction Heat Transfer (k, U, R, Q)

Conduction through a plane wall is often modeled with Fourier’s law in one dimension: q = k·(ΔT / L), where q is heat flux (W/m²), k is thermal conductivity (W/m·K), L is thickness (m) and ΔT is the temperature difference across the wall.

In the conduction tab you enter:

• Thermal conductivity k (W/m·K)
• Layer thickness L (m)
• Area A (m²)
• Temperatures on the hot and cold sides
• Your preferred temperature unit (°C, °F or K) and decimal precision

The calculator converts the temperatures to Kelvin internally, computes ΔT, then uses:

• R = L / k (m²·K/W) – conduction resistance of the layer
• U = 1 / R (W/m²·K) – conduction heat transfer coefficient
• Q = U·A·ΔT (W) – total heat transfer rate
• q = Q / A (W/m²) – corresponding heat flux

Mode 2 – Convection Heat Transfer Coefficient h

Convection between a surface and a fluid is often described using Newton’s law of cooling: q = h·(T_s − T_∞). If you know the heat flux and the surface and fluid temperatures, you can rearrange this to solve for h.

In the convection tab you provide:

• Heat flux q (W/m²)
• Surface temperature T_s
• Fluid (bulk) temperature T_∞
• Temperature unit (°C, °F or K) and decimal precision

The calculator converts temperatures to Kelvin to compute ΔT and then calculates the convection coefficient: h = q / ΔT. This is useful when estimating h from experimental measurements or when back-calculating h from known fluxes in equipment or building components.

Mode 3 – Radiation Heat Transfer Coefficient h_r

Thermal radiation between a surface and its surroundings can be described by the Stefan–Boltzmann law. For a diffuse, gray surface exchanging radiation with a large isothermal surrounding, an effective radiation coefficient h_r can be defined so that q ≈ h_r·(T_s − T_sur).

In the radiation tab you enter:

• Surface temperature T_s
• Surroundings temperature T_sur
• Emissivity ε between 0 and 1
• Temperature unit (°C, °F or K) and decimal precision

The tool converts temperatures to Kelvin, applies the Stefan–Boltzmann constant and reports:

• ΔT in Kelvin
• Effective radiation coefficient h_r (W/m²·K)
• Radiative heat flux q (W/m²)

Mode 4 – Overall Heat Transfer Coefficient U and Heat Flow

Many practical systems combine conduction through a wall and convection on both sides. The resistances add in series: 1/h₁ on the inside, L/k through the wall and 1/h₂ on the outside. The overall heat transfer coefficient U is then:

U = 1 / (1/h₁ + L/k + 1/h₂)

In the overall mode you specify:

• Inner convection coefficient h₁ (W/m²·K)
• Wall conductivity k (W/m·K) and thickness L (m)
• Outer convection coefficient h₂ (W/m²·K)
• Area A (m²)
• Inside and outside temperatures with unit (°C, °F or K)

The calculator sums the resistances, inverts to get U, computes ΔT and then reports Q = U·A·ΔT and the corresponding heat flux. For multi-layer constructions you can extend the method by combining several L/k terms into a total conduction resistance before using this tab.

Tips for Using the Heat Transfer Coefficient Calculator

• Keep units consistent for area, thickness and conductivity; the calculator assumes SI units (m, m², W/m·K).
• Use °C, °F or K for temperatures as convenient; the calculator handles the necessary conversions internally.
• Start with the conduction tab to understand how wall thickness and material affect U.
• Use the convection and radiation tabs to estimate h and h_r when building an overall resistance model.
• Finish in the overall tab to see the combined effect on U and Q for your system or building element.

The results are idealized steady-state values and do not include transient effects, multidimensional heat flow or complex geometries. Always combine these estimates with engineering judgment and, where needed, applicable codes and standards.

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