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Btus (th)/second/square foot/°F to Joules/second/square meter/K Converter (Btu (th)/(s·ft²·°F) to J/(s·m²·K))

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1 Btu (th)/second/square foot/°F = 20428.17453832 Joule/second/square meter/K
1 Btu (th)/(s·ft²·°F) = 20428.174538 J/(s·m²·K) • 1 J/(s·m²·K) = 4.8952 × 10⁻⁵ Btu (th)/(s·ft²·°F)
Btu (th)/second/square foot/°F to Joule/second/square meter/K: One Btu (th)/second/square foot/°F is equal to 20428.17453832 Joules/second/square meter/K.
Certified Authority Value
20428.17453832
J/(s·m²·K)
Exact: 1 J/(s·m²·K) ≡ 4.8952 × 10⁻⁵ Btu (th)/(s·ft²·°F)
Btu (th)/(s·ft²·°F)
Btu (th)/(s·ft²·°F)
Swap to Joule/second/square meter/K to Btu (th)/second/square foot/°F
Swap to Joule/second/square meter/K to Btu (th)/second/square foot/°F
J/(s·m²·K)
J/(s·m²·K) 20428.17453832
Quick Values:
Conversion Formula
To convert Btu (th)/second/square foot/°F to Joule/second/square meter/K, multiply by 20428.17453832
Btu (th)/(s·ft²·°F) × 20428.17453832 = J/(s·m²·K)

Calculation: 1 Btu (th)/(s·ft²·°F) × 20428.17453832 = 20428.17453832 J/(s·m²·K)

Common Btu (th)/second/square foot/°F to Joule/second/square meter/K Calculations

Quick-lookup reference table showing calculated equivalents for standard increments between Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) and Joule/second/square meter/K (J/(s·m²·K)).

Tap any row to calculate
Btu (th)/second/square foot/°F to Joule/second/square meter/K: Primary Direct Table (15 Steps)
Btu (th)/second/square foot/°F to Joule/second/square meter/K Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu (th)/(s·ft²·°F) 20.428175 J/(s·m²·K) 2.043 × 10¹
0.01 Btu (th)/(s·ft²·°F) 204.281745 J/(s·m²·K) 2.043 × 10²
0.1 Btu (th)/(s·ft²·°F) 2042.817454 J/(s·m²·K) 2.043 × 10³
0.5 Btu (th)/(s·ft²·°F) 10214.087269 J/(s·m²·K) 1.021 × 10⁴
1 Btu (th)/(s·ft²·°F) 20428.174538 J/(s·m²·K) 2.043 × 10⁴
2 Btu (th)/(s·ft²·°F) 40856.349077 J/(s·m²·K) 4.086 × 10⁴
5 Btu (th)/(s·ft²·°F) 102140.872692 J/(s·m²·K) 1.021 × 10⁵
10 Btu (th)/(s·ft²·°F) 204281.745383 J/(s·m²·K) 2.043 × 10⁵
20 Btu (th)/(s·ft²·°F) 408563.490766 J/(s·m²·K) 4.086 × 10⁵
25 Btu (th)/(s·ft²·°F) 510704.363458 J/(s·m²·K) 5.107 × 10⁵
50 Btu (th)/(s·ft²·°F) 1021408.726916 J/(s·m²·K) 1.021 × 10⁶
100 Btu (th)/(s·ft²·°F) 2042817.453832 J/(s·m²·K) 2.043 × 10⁶
250 Btu (th)/(s·ft²·°F) 5107043.634581 J/(s·m²·K) 5.107 × 10⁶
500 Btu (th)/(s·ft²·°F) 1.021409 × 10⁷ J/(s·m²·K) 1.021 × 10⁷
1000 Btu (th)/(s·ft²·°F) 2.042817 × 10⁷ J/(s·m²·K) 2.043 × 10⁷
Joule/second/square meter/K to Btu (th)/second/square foot/°F: Reciprocal Summary
Joule/second/square meter/K to Btu (th)/second/square foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 J/(s·m²·K) 4.8952 × 10⁻⁵ Btu (th)/(s·ft²·°F) 4.895 × 10⁻⁵
5 J/(s·m²·K) 0.00024476 Btu (th)/(s·ft²·°F) 2.448 × 10⁻⁴
10 J/(s·m²·K) 0.00048952 Btu (th)/(s·ft²·°F) 4.895 × 10⁻⁴
50 J/(s·m²·K) 0.0024476 Btu (th)/(s·ft²·°F) 2.448 × 10⁻³
100 J/(s·m²·K) 0.0048952 Btu (th)/(s·ft²·°F) 4.895 × 10⁻³
View Complete 15-Row Joule/second/square meter/K to Btu (th)/second/square foot/°F Table

Real-World Context & Everyday Benchmarks

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To help contextualize these units in everyday life, science, and engineering, here are verified real-world reference points for Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) and Joule/second/square meter/K (J/(s·m²·K)):

Btu (th)/second/square foot/°F References:

  • High-pressure steam boiler water-wall tube boiling coefficient 0.5 Btu (th)/(s·ft²·°F)

Joule/second/square meter/K References:

  • Equivalent to W/(m²·K): Forced water cooling jacket convection 2500 J/(s·m²·K)

Tap any benchmark above to automatically calculate its exact equivalent in Joule/second/square meter/K.

ISQ Dimension: [M T⁻³ Θ⁻¹] Coherent SI Unit: watt per square meter kelvin (W/(m²·K)) Thermodynamics & Heat Transfer

How to Convert Btu (th)/second/square foot/°F to Joule/second/square meter/K

Converting Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) to Joule/second/square meter/K (J/(s·m²·K)) is a core calculation in Heat Transfer Coefficient, which quantifies the proportionality constant between the heat flux and the thermodynamic driving temperature difference. This calculation navigates the boundary between the International Metric System (SI) and British Imperial / US Customary engineering standards. In contemporary metrology, Imperial units are defined in terms of exact SI standards via international agreements—notably NIST SP 811 and the 1959 International Yard and Pound Agreement. Exactly 1 Btu (th)/second/square foot/°F equals 20428.174538 Joule/second/square meter/K, while 1 J/(s·m²·K) equals 4.8952 × 10⁻⁵ Btu (th)/(s·ft²·°F).

Direct Factor1 Btu (th)/(s·ft²·°F) = 20428.174538 J/(s·m²·K)
Inverse Ratio1 J/(s·m²·K) = 4.8952 × 10⁻⁵ Btu (th)/(s·ft²·°F)
Conversion ScaleMetric SI to British Imperial / US Customary Bridge
First-Principles SI Derivation ProofNIST SP 811 / ISO 80000 Compliance

Mathematical Conversion Derivation via Coherent SI Base Unit

Under the International System of Quantities (ISQ), dimensional conversion between non-SI units is rigorously resolved by bridging through the coherent SI base unit (watt per square meter kelvin (W/(m²·K))) without arbitrary rounding:

Vtarget=Vsource×(ksource→SIktarget→SI)V_{\text{target}} = V_{\text{source}} \times \left( \frac{k_{\text{source} \to \text{SI}}}{k_{\text{target} \to \text{SI}}} \right)
Universal Dimensional Conversion Law (ISO 80000 / NIST SP 811)
1. Source SI Bridge (ksource):1 Btu (th)/(s·ft²·°F) = 20428.174538 watt per square meter kelvin (W/(m²·K))
2. Target SI Bridge (ktarget):1 J/(s·m²·K) = 1 watt per square meter kelvin (W/(m²·K))
Step-by-step substitution for Btu (th)/second/square foot/°F → Joule/second/square meter/K:V(J/(s·m²·K)) = V(Btu (th)/(s·ft²·°F)) × ( 20428.174538 / 1 ) = V(Btu (th)/(s·ft²·°F)) × 20428.174538
Mathematical FormulaValue in Joule/second/square meter/K = Value in Btu (th)/second/square foot/°F × 20428.17453832Direct computational formula applied for standard conversion.
Worked Example

To convert 24 Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) to Joule/second/square meter/K (J/(s·m²·K)): multiply 24 by 20428.174538 to get 490276.18892 J/(s·m²·K). At an industrial engineering scale, 2500 Btu (th)/(s·ft²·°F) converts to 5.107044 × 10⁷ J/(s·m²·K).

Inverse check: 1 J/(s·m²·K) = 4.8952 × 10⁻⁵ Btu (th)/(s·ft²·°F).

Understanding Btu (th)/second/square foot/°F and Joule/second/square meter/K

Btu (th)/second/square foot/°F

Btu (th)/(s·ft²·°F)
Imperial / US

A Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) is an imperial and US customary unit for heat transfer coefficient.

Applications & Practical Context

In practical heat transfer coefficient terms, a high-pressure steam boiler water-wall tube boiling coefficient equals 0.5 Btu (th)/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu (th)/(s·ft²·°F) corresponds to 20428.174538 W/(m²·K) in standard SI measurement.

Conversion to SI Unit: watt per square meter kelvin (W/(m²·K))
1 Btu (th)/(s·ft²·°F) = 20428.174538 W/(m²·K)

Joule/second/square meter/K

J/(s·m²·K)
Standard Unit

A Joule/second/square meter/K (J/(s·m²·K)) is a recognized unit for heat transfer coefficient.

Applications & Practical Context

In practical heat transfer coefficient terms, a equivalent to W/(m²·K): Forced water cooling jacket convection equals 2500 J/(s·m²·K).

Physical Setup

A heat transfer coefficient of 1 J/(s·m²·K) yields 1 watt of thermal energy transfer per square meter for each kelvin difference.

Conversion to SI Unit: watt per square meter kelvin (W/(m²·K))
1 J/(s·m²·K) = 1 W/(m²·K)

Domain Metrology & Engineering Applications

Governing Law & Equation

Newton's Law of Cooling (q = h · ΔT)

Measurement Instrumentation

Rigorously quantified in laboratory and field settings using surface heat flux transducer plates coupled with surface RTD arrays, and wind tunnel boundary layer calorimeters.

Primary Industry Sectors

Applied across industrial heat exchanger rating, nuclear reactor cooling loop simulation, electronics forced-air cooling, and architectural U-value certification under international metrology standard ISO 80000-5:2019, ASME PTC.

Institutional Metrology & Standard Authority:

Formulas, conversion coefficients, and base definitions on this page strictly adhere to the ISO 80000-5:2019, ASME PTC and the BIPM SI Brochure (9th Edition). Governed by Newton's Law of Cooling (q = h · ΔT) under ISO 80000 dimensional vector [M T⁻³ Θ⁻¹].

Multi-Variable Engineering Bridge Convective Thermodynamics & Cooling

Heat Transfer Coefficient to Convective Flux Bridge (W/m² • kW/m² • BTU/(h·ft²) • cal/(s·cm²))

Calculate Newton’s law of cooling convective heat flux q" = h × ΔT across convective film temperature drops, bridging heat transfer coefficient [M T⁻³ Θ⁻¹] with heat flux [M T⁻³].

q" = h × ΔT
Vector: [W/(m²·K)] × [K] → [W/m²]
Live Calculated Bridge Equivalent:
1 Btu (th)/(s·ft²·°F) at Forced Air Duct Cooling (ΔT = 25 K) = 510704.3635 W/m²
Equals 510.7044 kW/m² • 161892.464 BTU/(h·ft²) • 12.197964 cal/(s·cm²)
SI Heat Flux
510704.3635
W/m²
Watts per Square Meter
Solar / Combustion
510.7044
kW/m²
Kilowatts per Square Meter
US Building Envelope
161892.464
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
12.197964
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
732.0096
Ly/min
Langley per Minute
Furnace Flux
0.510704
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m²·K)):
    h = 1 Btu (th)/(s·ft²·°F) × 20428.17453832 = 20428.17453832 W/(m²·K)
  2. 2. Apply Engineering Parameter (ΔT):
    Selected condition: Forced Air Duct Cooling (ΔT = 25 K) at ΔT = 25 K
  3. 3. Execute Governing Physical Law in SI Units:
    q" = h × ΔT = (20428.17453832 W/(m²·K)) × (25 K) = 510704.363458 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 510704.363458 × 1 = 510704.3635 W/m² (Watts per Square Meter) • kW/m²: 510704.363458 × 0.001 = 510.7044 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 510704.363458 × 0.317 = 161892.464 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 510704.363458 × 2.3885 × 10⁻⁵ = 12.197964 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 510704.363458 × 0.001433 = 732.0096 Ly/min (Langley per Minute) • MW/m²: 510704.363458 × 1 × 10⁻⁶ = 0.510704 MW/m² (Megawatts per Square Meter)
Explore Full Heat Flux Density Converter →
Engineering Substance / Operating Standard Parameter Value (K) Reference State / Condition Typical Industrial & Engineering Application
Natural Air Convection (ΔT = 15 K) 15 ΔT = 15 K (15°C) Still room air room heating surface delta
Forced Air Duct Cooling (ΔT = 25 K) 25 ΔT = 25 K (25°C) Forced fan ventilation heatsink airflow
Forced Liquid Water Cooling (ΔT = 30 K) 30 ΔT = 30 K Pumped liquid cold plate or engine jacket
Nucleate Boiling Heat Transfer (ΔT = 50 K) 50 ΔT = 50 K Boiler evaporator tube wall boundary
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Frequently Asked Questions

There are exactly 20428.17453832 joules/second/square meter/k (J/(s·m²·K)) in 1 btu (th)/second/square foot/°f (Btu (th)/(s·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btus (th)/second/square foot/°f by the conversion multiplier of 20428.17453832.

The mathematical formula to convert btus (th)/second/square foot/°f to joules/second/square meter/k is: [value] * 20428.17453832 = joules/second/square meter/k. Rather than doing the math manually, you can use our high-precision online calculator to process this exact equation instantly without rounding errors.

To perform the reverse calculation from joules/second/square meter/k back to btus (th)/second/square foot/°f, you must divide your starting value by 20428.17453832. Our bidirectional tool automatically computes this inverse equation the moment you type into the joule/second/square meter/k input field.

1 Btu (th)/second/square foot/°F is larger than 1 Joule/second/square meter/K. Specifically, 1 Btu (th)/second/square foot/°F equals exactly 20428.17453832 joules/second/square meter/k, making it 20428.1745 times larger (a difference of 4.31 orders of magnitude). Therefore, quantities expressed in joules/second/square meter/k require a larger numerical value to represent the same physical amount.

Under standard international measurement guidelines, 1 Btu (th)/second/square foot/°F converts to 20428.17453832 joules/second/square meter/k. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.