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Thermal Conductivity & Heat Transfer Coefficient Converter

Convert between thermal conductivity (W/(m·K), BTU/(hr·ft·°F), kcal/(hr·m·°C)) and building insulation heat transfer coefficients (U-value, imperial U-factor, RSI, and R-value).

Fluid & Thermodynamic Laboratory Engine

4 Units Available

Sci Notation

Decimals:

SOURCE VALUE:W/(m·K)

CONVERTED RESULT:

57.7789

Reference Presets:

Exact Mathematical Derivation:

1. Base SI value: 100 W/(m·K) × 1 = 100

2. Target unit factor: 1 BTU/(hr·ft·°F) = 1.730735 SI base

3. Result: 100 / 1.730735 = 57.7789 BTU/(hr·ft·°F)

Complete Conversion TableClick copy on any row

Unit Name	Symbol	Converted Value
Watt / (meter·Kelvin)	W/(m·K)	100
BTU / (hour·foot·°F)	BTU/(hr·ft·°F)	57.7789
BTU·inch / (hr·ft²·°F)	BTU·in/(hr·ft²·°F)	693.3471
Kilocalorie / (hour·meter·°C)	kcal/(hr·m·°C)	85.9845

What is Thermal Conductivity and U-Value?

Thermal conductivity ($k$ or $\lambda$) measures a material's intrinsic ability to conduct heat ($q = -k \nabla T$), with SI units $\text{W}/(\text{m}\cdot\text{K})$.

Building envelope physics uses the overall heat transfer coefficient (U-value in $\text{W}/(\text{m}^2\cdot\text{K})$) and its reciprocal thermal resistance R-value ($R = 1/U$). US building codes specify R-values in $\text{hr}\cdot\text{ft}^2\cdot{^\circ}\text{F}/\text{BTU}$.

Formula & Step-by-Step Calculation

1\,\text{W}/(\text{m}\cdot\text{K}) = 0.577789\,\text{BTU}/(\text{hr}\cdot\text{ft}\cdot{^\circ}\text{F}), \quad R_{\text{US}} = R_{\text{SI}} \times 5.678263

Conversion factors between SI and Imperial thermal transmission metrics.

Worked Step-by-Step Examples

Example 1

Convert fiberglass insulation thermal conductivity k = 0.040 W/(m·K) to BTU/(hr·ft·°F).

Solution: 0.040 W/(m·K) ≈ 0.0231 BTU/(hr·ft·°F)

• Multiply by 0.577789: 0.040 × 0.577789 ≈ 0.02311 BTU/(hr·ft·°F).

Common Real-World & Academic Use Cases

✓ Building architecture insulation specification (converting metric RSI to US R-values)
✓ Electronic heat sink and thermal interface material (TIM) thermal conductivity selection
✓ Cryogenic insulation and spacecraft heat shield ceramic thermal barrier analysis
✓ Heat exchanger surface area thermal conductance calculations

How to Use the Thermal Conductivity & Heat Transfer Coefficient Converter

Input Value

Type thermal conductivity or resistance value.

Choose Metric Type

Select Conductivity (W/(m·K)) or Insulation (U-value / R-value).

Review Equivalencies

Check multi-unit converted values and standard insulation guidelines.

Frequently Asked Questions

Q: What is the relationship between U-value and R-value?

U-value and R-value are mathematical reciprocals: R = 1 / U. A lower U-value or higher R-value denotes superior thermal insulation.

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