Heat Transfer Calculator
Conduction heat loss through a wall.
Enter your values
Enter the area in m².
Enter the thickness in m.
Enter the conductivity in W/mK.
Enter the temperature difference in °C.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Heat loss
- 1036.8 W
- Daily energy
- 24.88 kWh
- U-value
- 2.4 W/m²K
- Annual cost at $0.25/kWh
- $1,119.74
Quick answer
Conductive heat loss rises with area and temperature difference and falls with thickness.
Q = k × A × ΔT ÷ thickness
At a glance
| What it does | Conduction heat loss through a wall. |
|---|---|
| Category | Engineering |
| Inputs needed | Area, Thickness, Conductivity, Temperature difference |
| Main output | Heat loss |
| Formula | Q = k × A × ΔT ÷ thickness |
| Cost | Free — no sign-up, no download |
How to use the Heat Transfer Calculator
- 1Enter wall area and thickness.
- 2Enter the material's thermal conductivity.
- 3Enter the inside-outside temperature difference.
Inputs explained
- Area(m²)
- Enter the area in m².
- Thickness(m)
- Enter the thickness in m.
- Conductivity(W/mK)
- Enter the conductivity in W/mK.
- Temperature difference(°C)
- Enter the temperature difference in °C.
Worked example
Using the values the calculator loads with:
Inputs
- Area24 m²
- Thickness0.25 m
- Conductivity0.6 W/mK
- Temperature difference18 °C
Results
- Heat loss1036.8 W
- Daily energy24.88 kWh
- U-value2.4 W/m²K
- Annual cost at $0.25/kWh$1,119.74
Frequently asked questions
What is a good U-value?
Below 0.3 W/m²K for modern insulated walls.
Does this include air films?
No — real U-values add internal and external surface resistances.
What do I need to enter into the Heat Transfer Calculator?
Just 4 values: area, thickness, conductivity, temperature difference. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Heat Transfer Calculator work out the answer?
Conductive heat loss rises with area and temperature difference and falls with thickness. It applies the formula Q = k × A × ΔT ÷ thickness and shows the working so you can check each step by hand.
Is the Heat Transfer Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.