Understanding Milliwatts per Metre-Kelvin to Calories per Second-Centimetre-Degree Celsius Conversion
The milliwatt per metre-kelvin (mW/(m·K)) is the metric measure of thermal conductivity in SI-derived units. The calorie per second-centimetre-degree Celsius (cal/(s·cm·°C)) is the older CGS thermal-conductivity unit still seen in physics literature, materials-science tables, and thermodynamics texts, where heat flow is measured in calories per second through a centimetre thickness. This conversion helps modern SI figures line up with historical CGS data for metals, minerals, and other materials.
Conversion Formula
To convert Milliwatts per Metre-Kelvin to Calories per Second-Centimetre-Degree Celsius, multiply by this factor:
Step-by-Step Example
Convert 25 Milliwatts per Metre-Kelvin to Calories per Second-Centimetre-Degree Celsius.
How to Convert Milliwatts per Metre-Kelvin to Calories per Second-Centimetre-Degree Celsius
Convert the SI conductivity unit to the older CGS calorie-based unit with a single multiplication.
- Recall the factor: One mW/(m·K) equals 2.390057 × 10⁻⁶ cal/(s·cm·°C).
- Take your value: Note the conductivity in milliwatts per metre-kelvin.
- Multiply: Multiply that value by 2.390057 × 10⁻⁶ to reach cal/(s·cm·°C).
- Result: For 25 mW/(m·K), the result is 25 × 2.390057 × 10⁻⁶ = 5.975143 × 10⁻⁵ cal/(s·cm·°C).
Milliwatts per Metre-Kelvin to Calories per Second-Centimetre-Degree Celsius conversion table
| Milliwatts per Metre-Kelvin (mW/(m-K)) | Calories per Second-Centimetre-Degree Celsius (cal/(s-cm-°C)) |
|---|---|
| 0 | 0 |
| 1 | 0.000002390057 |
| 2 | 0.000004780115 |
| 3 | 0.000007170172 |
| 4 | 0.000009560229 |
| 5 | 0.00001195029 |
| 6 | 0.00001434034 |
| 7 | 0.0000167304 |
| 8 | 0.00001912046 |
| 9 | 0.00002151052 |
| 10 | 0.00002390057 |
| 15 | 0.00003585086 |
| 20 | 0.00004780115 |
| 25 | 0.00005975143 |
| 30 | 0.00007170172 |
| 40 | 0.00009560229 |
| 50 | 0.0001195029 |
| 60 | 0.0001434034 |
| 70 | 0.000167304 |
| 80 | 0.0001912046 |
| 90 | 0.0002151052 |
| 100 | 0.0002390057 |
| 150 | 0.0003585086 |
| 200 | 0.0004780115 |
| 250 | 0.0005975143 |
| 300 | 0.0007170172 |
| 400 | 0.0009560229 |
| 500 | 0.001195029 |
| 600 | 0.001434034 |
| 700 | 0.00167304 |
| 800 | 0.001912046 |
| 900 | 0.002151052 |
| 1000 | 0.002390057 |
| 2000 | 0.004780115 |
| 3000 | 0.007170172 |
| 4000 | 0.009560229 |
| 5000 | 0.01195029 |
| 10000 | 0.02390057 |
| 25000 | 0.05975143 |
| 50000 | 0.1195029 |
| 100000 | 0.2390057 |
| 250000 | 0.5975143 |
| 500000 | 1.195029 |
| 1000000 | 2.390057 |
What is the Milliwatt per Metre-Kelvin?
The milliwatt per metre-kelvin is a unit of thermal conductivity equal to one thousandth of a watt per metre-kelvin. Its convenient scale makes it the preferred unit for describing thermal insulators and gases, whose conductivities are small fractions of a watt per metre-kelvin.
Definition
One milliwatt per metre-kelvin is 10⁻³ watt per metre-kelvin, the SI unit of thermal conductivity:
Like its parent unit, it may equivalently be written mW/(m·°C), since a one-kelvin interval equals a one-degree-Celsius interval.
Origin and History
The unit is simply the SI watt per metre-kelvin scaled by the standard milli- prefix (10⁻³). It became common in the insulation, cryogenics and gas-property literature during the twentieth century, where reporting figures such as 26 mW/(m·K) for air is clearer than 0.026 W/(m·K).
Law and Notable Facts
The milliwatt per metre-kelvin is a coherent SI unit with a decimal prefix and is legal for use worldwide. Building-insulation performance is often stated in mW/(m·K): the lower the value, the better the insulator, which is why manufacturers compete to push products below 30 mW/(m·K).
Real-World Examples and Conversions
- Dry air at room temperature conducts heat at about 26 mW/(m·K).
- Mineral wool and glass-fibre insulation typically fall between 30 and 40 mW/(m·K).
- Polyurethane foam boards reach roughly 22–25 mW/(m·K).
- 1 mW/(m·K) = 0.001 W/(m·K); conversely 1 W/(m·K) = 1000 mW/(m·K).
What is the Calorie per Second-Centimetre-Degree Celsius?
The calorie per second-centimetre-degree Celsius is the CGS-based unit of thermal conductivity, historically common in physics and physical-chemistry literature. It measures the heat in calories flowing per second through a one-centimetre thickness for each degree Celsius of temperature difference.
Definition
One calorie per second-centimetre-degree Celsius represents a heat flow of one calorie per second through a one-centimetre cube per degree Celsius across it. Using the thermochemical calorie (4.184 J):
The value follows from 4.184 J/s per (0.01 m · 1 K) = 4.184 ÷ 0.01 = 418.4 W/(m·K). If the International Table calorie (4.1868 J) is used instead, the factor is 418.68 W/(m·K).
Origin and History
The unit arose in the CGS era, when heat was measured in calories, lengths in centimetres and temperature in degrees Celsius. It appears throughout older thermal-conductivity tables and heat-transfer texts, especially in chemistry and metallurgy, before the watt per metre-kelvin became standard.
Law and Notable Facts
Though largely superseded by SI, the unit is still encountered in legacy data and some scientific traditions. Its large size is convenient for metals: because 1 cal/(s·cm·°C) equals 418.4 W/(m·K), even highly conductive copper is under 1 in these units, whereas most materials are small fractions.
Real-World Examples and Conversions
- Copper conducts at about 0.94 cal/(s·cm·°C), i.e. roughly 400 W/(m·K).
- Iron is about 0.18 cal/(s·cm·°C).
- Water is roughly 0.0014 cal/(s·cm·°C).
- 1 cal/(s·cm·°C) = 418.4 W/(m·K); conversely 1 W/(m·K) ≈ 0.00239 cal/(s·cm·°C).
Frequently Asked Questions
How many cal/(s·cm·°C) equal one milliwatt per metre-kelvin?
One milliwatt per metre-kelvin equals about 2.390057 × 10⁻⁶ cal/(s·cm·°C), a small value because the calorie-based CGS unit is much larger.
How do I convert mW/(m·K) to cal/(s·cm·°C)?
Multiply the mW/(m·K) value by 2.390057 × 10⁻⁶. For example, 25 mW/(m·K) equals 5.975143 × 10⁻⁵ cal/(s·cm·°C).
Why is the CGS conductivity unit still used?
Many classic materials-science and physics references tabulate thermal conductivity in cal/(s·cm·°C), so the unit persists when consulting older data on metals and minerals.
How many milliwatts per metre-kelvin equal one cal/(s·cm·°C)?
The reverse factor is 418,400 mW/(m·K) per cal/(s·cm·°C), which follows directly from the thermochemical calorie being 4.184 joules.
Which calorie definition does this use?
It uses the thermochemical calorie of exactly 4.184 joules, giving the exact ratio between the SI and CGS thermal-conductivity units.
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Complete Milliwatts per Metre-Kelvin conversion table
| Unit | Result |
|---|---|
| Watts per Metre-Kelvin (W/(m-K)) | 0.001 W/(m-K) |
| BTU per Hour-Foot-Degree Fahrenheit (BTU/(h-ft-°F)) | 0.0005777893 BTU/(h-ft-°F) |
| BTU-Inch per Hour-Square Foot-Degree Fahrenheit (BTU-in/(h-ft2-°F)) | 0.006933472 BTU-in/(h-ft2-°F) |
| Calories per Second-Centimetre-Degree Celsius (cal/(s-cm-°C)) | 0.000002390057 cal/(s-cm-°C) |