Heat TransferCalculator
Calculate conductive heat transfer via Fourier's Law and convective heat loss via Newton's Law of Cooling.
Heat Transfer Mechanism
Thermal Energy Transfer
Heat Transfer Calculator - Free Conduction & Convection Solver: Calculate thermal conduction, convection, and radiative heat transfer rates. Fast, free, and secure client-side execution in your browser.
How to Use the Heat Transfer Calculator
Select Heat Mode
Choose Conduction through solid walls or Convection between solid surfaces and surrounding fluids.
Input Boundary Temperatures
Enter hot side (T1) and cold side (T2) temperatures to determine the thermal gradient ΔT.
Define Material Properties
Enter thermal conductivity (k) and thickness (d) for conduction, or convection coefficient (h).
Evaluate Heat Dissipation
Review rate of heat loss in Watts, Kilowatts, and BTU/hr alongside thermal resistance.
Thermodynamics of Heat Transfer: Conduction, Convection, and Thermal Resistance
Heat transfer is the thermal energy transition driven by temperature differences between adjacent physical systems. The second law of thermodynamics establishes that thermal energy naturally migrates from higher-temperature regions toward lower-temperature environments until thermal equilibrium is achieved. Engineering applications—from building envelope insulation to electronic microprocessor heat sinks—require precisely regulating this transfer rate.
Conduction occurs via microscopic molecular collisions and electron diffusion through stationary matter. Governed by Fourier’s Law, the conductive heat transfer rate through a planar barrier is: Q = k × A × (T1 − T2) / d, where k is material thermal conductivity, A is surface area, and d is material thickness. Highly conductive materials like copper (k ≈ 400 W/m·K) rapidly dissipate heat, whereas thermal insulations like fiberglass or foam (k ≈ 0.03 W/m·K) impede energy transfer.
Convection describes heat transfer between a solid surface and an adjacent moving fluid (gas or liquid). Governed by Newton’s Law of Cooling, convective transfer is: Q = h × A × (Ts − T∞), where h is the convective heat transfer coefficient. The value of h varies from modest values (5 to 25 W/m²·K) in natural air convection to intense regimes (exceeding 10,000 W/m²·K) in boiling water or forced-liquid cooling systems.
Thermal resistance (R-value) provides an electrical circuit analogy for analyzing multi-layer composite walls. In this framework, temperature difference serves as voltage potential, heat flow rate acts as electric current, and thermal resistance represents electrical resistance. Summing conductive and convective resistances in series allows engineers to calculate overall heat transmission coefficients (U-values).
Key Advantages & Analytical Value
Fourier & Newton Modes
Accurately computes both solid conductive barriers and fluid convective boundaries.
Metric & Imperial Power Units
Simultaneously generates heat transfer in Watts (W), Kilowatts (kW), and BTU/hr.
Thermal Resistance (K/W)
Calculates true physical thermal resistance to simplify composite thermal circuit design.
Heat Flux Density
Reports heat dissipation per unit area (W/m²) for sizing electronics cooling pads.
100% Client-Side Privacy
Size HVAC equipment and proprietary semiconductor heat sinks completely in-browser.
Zero Latency Math
Live calculations update instantaneously as thermal parameters and thicknesses change.
Frequently Asked Questions
Fourier's Law states that the rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area through which heat flows: Q = k × A × ΔT / d.
Conduction is heat transfer through stationary matter via direct molecular contact. Convection is heat transfer between a surface and a moving fluid (gas or liquid).
A high thermal conductivity means the material conducts heat rapidly (e.g., metals like copper or aluminum). A low conductivity indicates a good thermal insulator (e.g., fiberglass, aerogel).
Multiply Watts by 3.412142 to obtain British Thermal Units per hour (BTU/hr).
Thermal resistance (R-value) is a measure of a material or boundary’s resistance to heat flow, calculated as d / (k × A) for conduction or 1 / (h × A) for convection.