Heat Transfer Calculator
Calculate heat transfer using conduction, convection, radiation, and sensible heat modes. Free online heat transfer calculator with material presets and interactive charts.
About This Calculator
The Heat Transfer Calculator computes thermal energy transfer across four fundamental modes: basic sensible heat (Q = mcΔT), conduction through solids (Fourier's law Q̇ = kAΔT/L), convection at fluid-solid interfaces (Newton's law of cooling Q̇ = hAΔT), and thermal radiation (Stefan-Boltzmann law Q̇ = εσA(Th⁴ − Tc⁴)). Engineers, physics students, HVAC professionals, and architects use this tool to solve heat transfer problems in design, analysis, and education.
Each mode includes presets from a comprehensive materials database. For sensible heat, select from specific heat values of 30+ materials. For conduction, choose from 15+ materials with known thermal conductivities. For radiation, the emissivity database covers surfaces from polished aluminum foil (ε=0.04) to black body (ε=1.0). The calculator displays a full parameter breakdown and interactive charts for each calculation.
Regional Notes
India: Energy Conservation Building Code (ECBC) 2017 specifies maximum U-values for building envelopes based on climate zones. Common construction materials include brick (k=0.6 W/m·K), concrete (1.8), and fly ash bricks. Bureau of Energy Efficiency (BEE) provides guidelines for HVAC system design.
United States: ASHRAE Handbook provides standard convective coefficients (indoor still air 8.3 W/m²·K, outdoor 34.1 W/m²·K at 24 km/h wind). IECC 2024 specifies building envelope U-values. Common insulation materials include fiberglass (k=0.04), foam board (0.03), and spray foam (0.02).
United Kingdom: Building Regulations Part L (2021) sets U-value targets for new buildings (walls ≤0.18, roofs ≤0.15, floors ≤0.18 W/m²·K). CIBSE Guide A provides environmental design data including convective heat transfer coefficients and material properties for UK climate conditions.
Frequently Asked Questions
What is the difference between conduction, convection, and radiation heat transfer?
Conduction is the transfer of heat through direct contact between molecules in solids, governed by Fourier's law Q̇ = kAΔT/L. Convection involves heat transfer through fluid motion using Newton's law of cooling Q̇ = hAΔT. Radiation is electromagnetic heat transfer requiring no medium, calculated via the Stefan-Boltzmann law Q̇ = εσA(Th⁴ − Tc⁴). This calculator supports all three modes plus basic sensible heat Q = mcΔT.
How does the basic sensible heat calculation work?
The basic mode uses Q = m × c × ΔT, where m is the mass in kg, c is the specific heat capacity of the material in J/(kg·°C), and ΔT is the temperature change. Select a material from the preset database (water, aluminum, copper, steel, etc.) and enter the initial and final temperatures. The result shows heat transferred in joules, kilojoules, and kilowatt-hours.
What is thermal conductivity and how does it affect conduction?
Thermal conductivity k measures a material's ability to conduct heat, expressed in W/(m·K). High-conductivity materials like copper (401 W/m·K) and aluminum (237) transfer heat rapidly, while insulators like air (0.024) and urethane foam (0.022) resist heat flow. In conduction mode, the heat transfer rate Q̇ = kAΔT/L increases with higher k, larger area A, greater temperature difference ΔT, and decreases with thicker material L.
What is a typical convective heat transfer coefficient?
Typical convective heat transfer coefficients vary widely: natural air convection (still air) 5-25 W/m²·K, forced air convection (fan) 10-200 W/m²·K, natural water convection 20-1000 W/m²·K, boiling water 1000-5000 W/m²·K, and condensing steam 5000-10000 W/m²·K. For building heat loss calculations, typical indoor still air values are 8 W/m²·K and outdoor windy conditions 23 W/m²·K.
How does emissivity affect radiative heat transfer?
Emissivity ε ranges from 0 (perfect reflector) to 1 (perfect black body). High-emissivity materials like ice (0.97), water (0.96), and brick (0.90) are efficient radiators. Low-emissivity materials like aluminum foil (0.04) reflect radiant heat. The Stefan-Boltzmann law Q̇ = εσA(Th⁴ − Tc⁴) shows heat transfer increases linearly with emissivity and with the fourth power of absolute temperature.
What is the Stefan-Boltzmann constant?
The Stefan-Boltzmann constant σ = 5.670367 × 10⁻⁸ W/(m²·K⁴) relates the power radiated by a black body to its temperature. It appears in the Stefan-Boltzmann law for radiative heat transfer. The fourth-power relationship means doubling the absolute temperature increases radiative heat transfer by a factor of 16.
Can this calculator be used for HVAC and building design?
Yes, the conduction mode helps calculate heat loss through walls, windows, and building envelopes using material thermal conductivity. The convection mode evaluates heat transfer at surfaces. The radiation mode calculates radiant heat exchange. India's ECBC, US IECC, and UK Building Regulations all specify maximum U-values for energy compliance, and this calculator helps determine the heat transfer rates needed for load calculations.
What materials are available in the specific heat preset database?
The preset database includes water (4186 J/kg·°C), aluminum (897), copper (385), iron (450), steel (500), brass (380), silver (235), gold (129), glass (840), wood (1700), concrete (880), brick (840), granite (790), marble (880), sand (830), soil (800), air (1005), ethanol (2440), oil (2000), ice (2108), steam (1996), and many more. Each value is sourced from standard engineering reference tables.