{
    "name": "Convection Heat Transfer Calculator",
    "url": "https://calculators.geekmidst.com/calculators/convection-heat-transfer-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/convection-heat-transfer-calculator.md",
    "category": "Science & engineering",
    "description": "Find the convective heat flow between a surface and the surrounding air or liquid from the heat transfer coefficient, area and temperature difference.",
    "summary": "Convective heat flow is Q̇ = hA(T_s − T_∞). The hard part is the coefficient h, which depends on the fluid and how fast it moves; typical ranges are given below.",
    "also_called": [
        "Newton’s law of cooling calculator",
        "Convective heat loss calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "h",
            "label": "Heat transfer coefficient (h)",
            "type": "number",
            "default": "25",
            "unit": "W/(m²·K)"
        },
        {
            "name": "area",
            "label": "Surface area",
            "type": "number",
            "default": "2",
            "unit": "m²"
        },
        {
            "name": "t_surface",
            "label": "Surface temperature",
            "type": "number",
            "default": "80",
            "unit": "°C"
        },
        {
            "name": "t_fluid",
            "label": "Fluid temperature (away from the surface)",
            "type": "number",
            "default": "20",
            "unit": "°C"
        }
    ],
    "outputs": [
        {
            "key": "heat_flow_w",
            "label": "Heat flow from the surface",
            "format": "number"
        },
        {
            "key": "heat_flux",
            "label": "Heat flux",
            "format": "number"
        },
        {
            "key": "resistance_kw",
            "label": "Convective resistance 1 ÷ (hA)",
            "format": "number"
        },
        {
            "key": "direction",
            "label": "Direction",
            "format": "text"
        }
    ],
    "formula": {
        "text": "Q̇ = h × A × (T_s − T_∞);  R_conv = 1 ÷ (h × A)",
        "variables": {
            "h": "convective heat transfer coefficient",
            "A": "surface area in contact with the fluid",
            "T_s": "surface temperature",
            "T_∞": "bulk fluid temperature"
        }
    },
    "worked_example": {
        "inputs": {
            "h": "25",
            "area": "2",
            "t_surface": "80",
            "t_fluid": "20"
        },
        "steps": [
            "ΔT = 80 − 20 = 60 K.",
            "Q̇ = 25 × 2 × 60 = 3000 W (1500 W/m²).",
            "R_conv = 1 ÷ (25 × 2) = 0.02 K/W."
        ],
        "result": "A 2 m² surface at 80 °C in moving air at 20 °C with h = 25 W/(m²·K) loses about 3 kW by convection."
    },
    "interpretation": "A positive result is heat leaving the surface. Hot surfaces also lose heat by radiation, which can be similar in size for still air, so add the Stefan–Boltzmann result for a total.",
    "assumptions": [
        "h is uniform over the surface and known.",
        "Temperatures are steady."
    ],
    "limitations": [
        "h is an estimate unless taken from a correlation (Nusselt number) for your geometry and flow; results are only as good as h."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "How do I get a better value of h?",
            "answer": "Use a Nusselt-number correlation for your geometry (flat plate, pipe, cylinder) with the Reynolds or Rayleigh number, or measured data."
        },
        {
            "question": "Is this the same as Newton’s law of cooling?",
            "answer": "Yes. Newton’s law of cooling states that the convective heat loss is proportional to the temperature difference, with h as the constant."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Conduction Heat Flow Calculator",
            "url": "https://calculators.geekmidst.com/calculators/conduction-heat-flow-calculator"
        },
        {
            "name": "Stefan–Boltzmann Radiation Calculator",
            "url": "https://calculators.geekmidst.com/calculators/radiation-stefan-boltzmann-calculator"
        },
        {
            "name": "Heat Capacity Calculator",
            "url": "https://calculators.geekmidst.com/calculators/heat-capacity-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}