# Heat Transfer Calculator

URL: https://speedycalculator.com/calculators/physics/heat-transfer/
Last updated: 2026-10-30

> The heat transfer calculator finds heat transferred by temperature change, the rate of conduction through a wall, convection from a surface, or radiation between a surface and its surroundings.

## Inputs

- Mode
- Mass m (kg, g, mg, t, lb, oz)
- Specific heat c (J/(kg·K), kJ/(kg·K), J/(g·K), BTU/(lb·°F), cal/(g·°C))
- Wall material
- Thermal conductivity k (W/(m·K), BTU/(h·ft·°F))
- Thickness d (cm, mm, m, in, ft)
- Heat transfer coefficient h (W/(m²·K), BTU/(h·ft²·°F))
- Emissivity ε
- Area A (m², cm², mm², km², in², ft²)
- Temperature 1 (hot) (°C, °F, K)
- Temperature 2 (cold) (°C, °F, K)

## Results

- Heat transferred
- Heat transfer rate

## Formula

```
Q = m·c·ΔT · Conduction: q = k·A·ΔT/d · Convection: q = h·A·ΔT · Radiation: q = ε·σ·A·(T₁⁴ − T₂⁴)
```

## Explanation

Heat moves by conduction through solids, convection by moving fluids and radiation by electromagnetic waves. Insulation, radiators, cooking and climate all depend on balancing these three.

### How to use the Heat Transfer Calculator

- **Mode**
- **Mass m**
- **Specific heat c**
- **Wall material**
- **Thermal conductivity k**
- **Thickness d**
- **Heat transfer coefficient h**
- **Emissivity ε**
- **Area A**
- **Temperature 1 (hot)**
- **Temperature 2 (cold)**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Choose the mode and enter the values.

### Tips

- Use absolute temperature (K) in gas laws and efficiency formulas.
- Temperature differences are the same in K and °C.
- Heat = mass × specific heat × temperature change when no phase change occurs.
- Phase changes need latent heat at a constant temperature.

### Common mistakes to avoid

- Using °C in pV = nRT.
- Forgetting latent heat during melting or boiling.
- Confusing heat capacity (J/K) with specific heat (J/(kg·K)).

### Inputs explained

FieldWhat to enterModeChoose one: Temperature change of a mass, Conduction, Convection, RadiationMass mUnits: kg, g, mg, t, lb, ozSpecific heat cUnits: J/(kg·K), kJ/(kg·K), J/(g·K), BTU/(lb·°F), cal/(g·°C)Wall materialChoose one: Copper, Aluminium, Carbon steel, Stainless steel …Thermal conductivity kUnits: W/(m·K), BTU/(h·ft·°F)Thickness dUnits: cm, mm, m, in, ftHeat transfer coefficient hUnits: W/(m²·K), BTU/(h·ft²·°F)Emissivity εA numberArea AUnits: m², cm², mm², km², in², ft²Temperature 1 (hot)Units: °C, °F, KTemperature 2 (cold)Units: °C, °F, K

### Example values

How the main result changes when **Mass m** changes and everything else stays at the example values above:

Mass m (kg)Heat transferred (J)0.541,8200.7562,730183,6401.25104,5501.5125,4602167,280

## Worked example

Inputs — Mode: Conduction; Wall material: Brick; Thickness d: 20 cm; Area A: 10 m²; Temperature 1 (hot): 20 °C; Temperature 2 (cold): 0 °C.

Results — **Heat transfer rate = 720 W**.

## Key terms

- **Thermal conductivity**: Heat flow per metre per kelvin.

## FAQ

**What are the three modes of heat transfer?**
Conduction, convection and radiation.

**Why does radiation use T⁴?**
Emitted power grows with the fourth power of absolute temperature.

**What is a typical h for still air?**
About 5–25 W/(m²·K).

**How do I reduce conduction losses?**
Use thicker material with lower conductivity.

**What formula does the Heat Transfer Calculator use?**
Q = m·c·ΔT · Conduction: q = k·A·ΔT/d · Convection: q = h·A·ΔT · Radiation: q = ε·σ·A·(T₁⁴ − T₂⁴).


## Sources

- [Incropera – Fundamentals of Heat and Mass Transfer (reference text)](https://www.wiley.com/en-us/Fundamentals+of+Heat+and+Mass+Transfer%2C+8th+Edition-p-9781119320425)
- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)