Heat Transfer Calculator
Calculate conduction heat transfer rate through flat materials using Fourier's Law
Last updated: April 2026
Understanding heat transfer through materials is essential when designing heat sealing equipment, industrial ovens, and thermal processing systems. Whether you are selecting PTFE-coated surfaces for a packaging line or sizing insulation for high-temperature equipment, knowing the rate of heat conduction through a material helps you make informed engineering decisions.
This calculator uses Fourier's Law of Heat Conduction to determine the steady-state heat transfer rate through a flat wall or surface. Enter your material properties, thickness, surface area, and temperature difference to instantly calculate the heat flow in watts, kilowatts, and heat flux.
PTFE (Teflon) has a thermal conductivity of just 0.25 W/m·K, making it one of the most effective polymer-based thermal insulators available. This is why thin PTFE tape on heat sealing jaws can protect packaging film from burning while still allowing controlled heat transfer through the tape to create a strong seal.
Enter Heat Transfer Parameters
Select a material or choose Custom to enter your own value
Auto-filled from material selection
Thickness of the wall or surface
Area through which heat is conducted
Temperature on the hotter surface
Temperature on the cooler surface
Fourier's Law of Heat Conduction
This calculator uses Fourier's Law for steady-state heat conduction through a flat wall:
Where:
- Q = heat transfer rate (W)
- k = thermal conductivity of the material (W/m·K)
- A = cross-sectional area perpendicular to heat flow (m²)
- ΔT = temperature difference across the material (K or °C)
- d = thickness of the material (m)
The formula assumes steady-state conditions, uniform material properties, and one-dimensional heat flow perpendicular to the surface. For thin materials like PTFE tape (typically 0.08–0.25 mm), even a small temperature difference can produce significant heat flux due to the very short conduction path.
Thermal Conductivity Reference Table
Common materials and their approximate thermal conductivity values at room temperature:
| Material | Thermal Conductivity (W/m·K) | Category |
|---|---|---|
| Copper | 385 | Metal |
| Aluminium | 205 | Metal |
| Carbon Steel | 50 | Metal |
| Stainless Steel | 16 | Metal |
| Glass | 1.0 | Non-metal |
| PTFE Coated Fibreglass | 0.35 | Polymer composite |
| PTFE (Teflon) | 0.25 | Polymer |
| Silicone Rubber | 0.2 | Elastomer |
Why PTFE Is Used in Heat Sealing
In heat sealing applications, the goal is to deliver enough thermal energy to melt and fuse packaging film without damaging the product inside. PTFE-coated surfaces achieve this by acting as a controlled thermal barrier. With a thermal conductivity of just 0.25 W/m·K, PTFE slows the rate of heat transfer compared to bare metal, giving operators more control over the sealing process. This is why PTFE tape is applied to heat sealer jaws, impulse sealer wires, and continuous band sealer belts across the food, medical, and industrial packaging sectors.
Frequently Asked Questions
Thermal conductivity (k) measures how easily heat passes through a material. In heat sealing, materials with low thermal conductivity like PTFE (0.25 W/m·K) act as controlled barriers, slowing heat transfer from the sealer jaw to the packaging film. This prevents overheating and gives operators better control over seal quality.
Thinner PTFE tape allows more heat to pass through per unit time because the conduction path is shorter. A 0.08 mm PTFE tape transfers roughly three times more heat than a 0.25 mm tape under the same conditions. Choosing the right thickness lets you balance seal strength with cycle speed.
No. This calculator models steady-state conduction through a flat wall only (Fourier's Law). In real-world heat sealing equipment, convection from surrounding air and radiation at high temperatures also contribute to the total heat transfer, but conduction through the contact surface is typically the dominant mechanism.
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