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Btu (it) Inches/second/sq. foot/°F to Btu (th) Inches/second/sq. foot/°F Converter (Btu·in/(s·ft²·°F) to Btu (th)·in/(s·ft²·°F))

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Live Conversion • ISO 80000-5:2019 Certified
1 Btu (IT) inch/second/sq. foot/°F = 1.00066922 Btu (th) inch/second/sq. foot/°F
1 Btu·in/(s·ft²·°F) = 1.000669 Btu (th)·in/(s·ft²·°F) • 1 Btu (th)·in/(s·ft²·°F) = 0.999331 Btu·in/(s·ft²·°F)
Btu (IT) inch/second/sq. foot/°F to Btu (th) inch/second/sq. foot/°F: One Btu (IT) inch/second/sq. foot/°F is equal to 1.00066922 Btu (th) Inches/second/sq. foot/°F.
Certified Authority Value
1.00066922
Btu (th)·in/(s·ft²·°F)
Exact: 1 Btu (th)·in/(s·ft²·°F) ≡ 0.9993312315 Btu·in/(s·ft²·°F)
Btu·in/(s·ft²·°F)
Btu·in/(s·ft²·°F)
Swap to Btu (th) inch/second/sq. foot/°F to Btu (IT) inch/second/sq. foot/°F
Swap to Btu (th) inch/second/sq. foot/°F to Btu (IT) inch/second/sq. foot/°F
Btu (th)·in/(s·ft²·°F)
Btu (th)·in/(s·ft²·°F) 1.00066922
Quick Values:
Conversion Formula
To convert Btu (IT) inch/second/sq. foot/°F to Btu (th) inch/second/sq. foot/°F, multiply by 1.00066922
Btu·in/(s·ft²·°F) × 1.00066922 = Btu (th)·in/(s·ft²·°F)

Calculation: 1 Btu·in/(s·ft²·°F) × 1.00066922 = 1.00066922 Btu (th)·in/(s·ft²·°F)

Common Btu (IT) inch/second/sq. foot/°F to Btu (th) inch/second/sq. foot/°F Calculations

Quick-lookup reference table showing calculated equivalents for standard increments between Btu (IT) inch/second/sq. foot/°F (Btu·in/(s·ft²·°F)) and Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)).

Tap any row to calculate
Btu (IT) inch/second/sq. foot/°F to Btu (th) inch/second/sq. foot/°F: Primary Direct Table (15 Steps)
Btu (IT) inch/second/sq. foot/°F to Btu (th) inch/second/sq. foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu·in/(s·ft²·°F) 0.00100067 Btu (th)·in/(s·ft²·°F) 1.001 × 10⁻³
0.01 Btu·in/(s·ft²·°F) 0.0100067 Btu (th)·in/(s·ft²·°F) 1.001 × 10⁻²
0.1 Btu·in/(s·ft²·°F) 0.100067 Btu (th)·in/(s·ft²·°F) 1.001 × 10⁻¹
0.5 Btu·in/(s·ft²·°F) 0.500335 Btu (th)·in/(s·ft²·°F) 5.003 × 10⁻¹
1 Btu·in/(s·ft²·°F) 1.000669 Btu (th)·in/(s·ft²·°F) 1.001 × 10⁰
2 Btu·in/(s·ft²·°F) 2.001338 Btu (th)·in/(s·ft²·°F) 2.001 × 10⁰
5 Btu·in/(s·ft²·°F) 5.003346 Btu (th)·in/(s·ft²·°F) 5.003 × 10⁰
10 Btu·in/(s·ft²·°F) 10.006692 Btu (th)·in/(s·ft²·°F) 1.001 × 10¹
20 Btu·in/(s·ft²·°F) 20.013384 Btu (th)·in/(s·ft²·°F) 2.001 × 10¹
25 Btu·in/(s·ft²·°F) 25.01673 Btu (th)·in/(s·ft²·°F) 2.502 × 10¹
50 Btu·in/(s·ft²·°F) 50.033461 Btu (th)·in/(s·ft²·°F) 5.003 × 10¹
100 Btu·in/(s·ft²·°F) 100.066922 Btu (th)·in/(s·ft²·°F) 1.001 × 10²
250 Btu·in/(s·ft²·°F) 250.167304 Btu (th)·in/(s·ft²·°F) 2.502 × 10²
500 Btu·in/(s·ft²·°F) 500.334608 Btu (th)·in/(s·ft²·°F) 5.003 × 10²
1000 Btu·in/(s·ft²·°F) 1000.669216 Btu (th)·in/(s·ft²·°F) 1.001 × 10³
Btu (th) inch/second/sq. foot/°F to Btu (IT) inch/second/sq. foot/°F: Reciprocal Summary
Btu (th) inch/second/sq. foot/°F to Btu (IT) inch/second/sq. foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu (th)·in/(s·ft²·°F) 0.999331 Btu·in/(s·ft²·°F) 9.993 × 10⁻¹
5 Btu (th)·in/(s·ft²·°F) 4.996656 Btu·in/(s·ft²·°F) 4.997 × 10⁰
10 Btu (th)·in/(s·ft²·°F) 9.993312 Btu·in/(s·ft²·°F) 9.993 × 10⁰
50 Btu (th)·in/(s·ft²·°F) 49.966562 Btu·in/(s·ft²·°F) 4.997 × 10¹
100 Btu (th)·in/(s·ft²·°F) 99.933123 Btu·in/(s·ft²·°F) 9.993 × 10¹
View Complete 15-Row Btu (th) inch/second/sq. foot/°F to Btu (IT) inch/second/sq. 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 (IT) inch/second/sq. foot/°F (Btu·in/(s·ft²·°F)) and Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)):

Btu (IT) inch/second/sq. foot/°F References:

  • Aerospace heat exchanger copper-alloy thermal conductor 0.077 Btu·in/(s·ft²·°F)

Btu (th) inch/second/sq. foot/°F References:

  • Aero-engine cooling jacket cast iron thermal conductivity 0.01 Btu (th)·in/(s·ft²·°F)

Tap any benchmark above to automatically calculate its exact equivalent in Btu (th) inch/second/sq. foot/°F.

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

How to Convert Btu (IT) inch/second/sq. foot/°F to Btu (th) inch/second/sq. foot/°F

Converting Btu (IT) inch/second/sq. foot/°F (Btu·in/(s·ft²·°F)) to Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)) is a core calculation in Thermal Conductivity, which measures a material's intrinsic capacity to conduct and transfer heat through microscopic collisions. 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 (IT) inch/second/sq. foot/°F equals 1.000669 Btu (th) inch/second/sq. foot/°F, while 1 Btu (th)·in/(s·ft²·°F) equals 0.999331 Btu·in/(s·ft²·°F).

Direct Factor1 Btu·in/(s·ft²·°F) = 1.000669 Btu (th)·in/(s·ft²·°F)
Inverse Ratio1 Btu (th)·in/(s·ft²·°F) = 0.999331 Btu·in/(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 meter kelvin (W/(m·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·in/(s·ft²·°F) = 519.2204 watt per meter kelvin (W/(m·K))
2. Target SI Bridge (ktarget):1 Btu (th)·in/(s·ft²·°F) = 518.873162 watt per meter kelvin (W/(m·K))
Step-by-step substitution for Btu (IT) inch/second/sq. foot/°F → Btu (th) inch/second/sq. foot/°F:V(Btu (th)·in/(s·ft²·°F)) = V(Btu·in/(s·ft²·°F)) × ( 519.2204 / 518.873162 ) = V(Btu·in/(s·ft²·°F)) × 1.000669
Mathematical FormulaValue in Btu (th) inch/second/sq. foot/°F = Value in Btu (IT) inch/second/sq. foot/°F × 1.00066922Direct computational formula applied for standard conversion.
Worked Example

Evaluating an input of 12 Btu (IT) inch/second/sq. foot/°F (Btu·in/(s·ft²·°F)) produces 12.008031 Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)). In heavy-duty utility and industrial workloads, 10000 Btu·in/(s·ft²·°F) equals 10006.692161 Btu (th)·in/(s·ft²·°F).

Inverse check: 1 Btu (th)·in/(s·ft²·°F) = 0.999331 Btu·in/(s·ft²·°F).

Understanding Btu (IT) inch/second/sq. foot/°F and Btu (th) inch/second/sq. foot/°F

Btu (IT) inch/second/sq. foot/°F

Btu·in/(s·ft²·°F)
Imperial / US

A Btu (IT) inch/second/sq. foot/°F (Btu·in/(s·ft²·°F)) is an imperial and US customary unit for thermal conductivity.

Applications & Practical Context

In practical thermal conductivity terms, a aerospace heat exchanger copper-alloy thermal conductor equals 0.077 Btu·in/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu·in/(s·ft²·°F) corresponds to 519.2204 W/(m·K) in standard SI measurement.

Conversion to SI Unit: watt per meter kelvin (W/(m·K))
1 Btu·in/(s·ft²·°F) = 519.2204 W/(m·K)

Btu (th) inch/second/sq. foot/°F

Btu (th)·in/(s·ft²·°F)
Imperial / US

A Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)) is an imperial and US customary unit for thermal conductivity.

Applications & Practical Context

In practical thermal conductivity terms, a aero-engine cooling jacket cast iron thermal conductivity equals 0.01 Btu (th)·in/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu (th)·in/(s·ft²·°F) corresponds to 518.873162 W/(m·K) in standard SI measurement.

Conversion to SI Unit: watt per meter kelvin (W/(m·K))
1 Btu (th)·in/(s·ft²·°F) = 518.873162 W/(m·K)

Domain Metrology & Engineering Applications

Governing Law & Equation

Fourier's Law of Heat Conduction (q = -k · ∇T)

Measurement Instrumentation

Rigorously quantified in laboratory and field settings using guarded hot plate apparatus (ASTM C177), laser flash thermal diffusivity analyzers, and transient plane source (TPS) sensors.

Primary Industry Sectors

Applied across thermal interface material (TIM) development, architectural insulation manufacturing, aerospace heat shield design, and refractory ceramics under international metrology standard ISO 80000-5:2019, ASTM C177.

Institutional Metrology & Standard Authority:

Formulas, conversion coefficients, and base definitions on this page strictly adhere to the ISO 80000-5:2019, ASTM C177 and the BIPM SI Brochure (9th Edition). Governed by Fourier's Law of Heat Conduction (q = -k · ∇T) under ISO 80000 dimensional vector [M L T⁻³ Θ⁻¹].

Multi-Variable Engineering Bridge Heat Transfer & Conduction Physics

Thermal Conductivity to Heat Flux Density Bridge (W/m² • kW/m² • BTU/(h·ft²) • cal/(s·cm²))

Calculate Fourier conduction heat flux q" = k × ∇T across building envelopes and industrial heat exchangers, bridging thermal conductivity [M L T⁻³ Θ⁻¹] with heat flux density [M T⁻³].

q" = k × ∇T
Vector: [W/(m·K)] × [K/m] → [W/m²]
Live Calculated Bridge Equivalent:
1 Btu·in/(s·ft²·°F) at Insulated Wall Core (20K across 0.1m = 200 K/m) = 103844.08 W/m²
Equals 103.8441 kW/m² • 32918.4068 BTU/(h·ft²) • 2.480273 cal/(s·cm²)
SI Heat Flux
103844.08
W/m²
Watts per Square Meter
Solar / Combustion
103.8441
kW/m²
Kilowatts per Square Meter
US Building Envelope
32918.4068
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
2.480273
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
148.8432
Ly/min
Langley per Minute
Furnace Flux
0.103844
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m·K)):
    k = 1 Btu·in/(s·ft²·°F) × 519.22039991 = 519.22039991 W/(m·K)
  2. 2. Apply Engineering Parameter (∇T):
    Selected condition: Insulated Wall Core (20K across 0.1m = 200 K/m) at ∇T = 200 K/m
  3. 3. Execute Governing Physical Law in SI Units:
    q" = k × ∇T = (519.22039991 W/(m·K)) × (200 K/m) = 103844.079982 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 103844.079982 × 1 = 103844.08 W/m² (Watts per Square Meter) • kW/m²: 103844.079982 × 0.001 = 103.8441 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 103844.079982 × 0.317 = 32918.4068 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 103844.079982 × 2.3885 × 10⁻⁵ = 2.480273 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 103844.079982 × 0.001433 = 148.8432 Ly/min (Langley per Minute) • MW/m²: 103844.079982 × 1 × 10⁻⁶ = 0.103844 MW/m² (Megawatts per Square Meter)
Explore Full Heat Flux Density Converter →
Engineering Substance / Operating Standard Parameter Value (K/m) Reference State / Condition Typical Industrial & Engineering Application
Insulated Wall Core (20K across 0.1m = 200 K/m) 200 200 K/m Standard residential fiberglass/mineral wool batt
Solid Brick Masonry (25K across 0.25m = 100 K/m) 100 100 K/m Architectural structural brick veneer wall
Steam Boiler Tube Wall (100K across 0.005m = 20,000 K/m) 20000 20,000 K/m Carbon steel heat recovery steam boiler tube
CPU Copper Heat Spreader (30K across 0.002m = 15,000 K/m) 15000 15,000 K/m Semiconductor thermal interface heat spreader
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Frequently Asked Questions

There are exactly 1.00066922 btu (th) inches/second/sq. foot/°f (Btu (th)·in/(s·ft²·°F)) in 1 btu (it) inch/second/sq. foot/°f (Btu·in/(s·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btu (it) inches/second/sq. foot/°f by the conversion multiplier of 1.00066922.

The mathematical formula to convert btu (it) inches/second/sq. foot/°f to btu (th) inches/second/sq. foot/°f is: [value] * 1.00066922 = btu (th) inches/second/sq. foot/°f. 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 btu (th) inches/second/sq. foot/°f back to btu (it) inches/second/sq. foot/°f, you must divide your starting value by 1.00066922. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (th) inch/second/sq. foot/°f input field.

1 Btu (IT) inch/second/sq. foot/°F is larger than 1 Btu (th) inch/second/sq. foot/°F. Specifically, 1 Btu (IT) inch/second/sq. foot/°F equals exactly 1.00066922 btu (th) inches/second/sq. foot/°f, making it 1.0007 times larger (a difference of 0.00 orders of magnitude). Therefore, quantities expressed in btu (th) inches/second/sq. foot/°f require a larger numerical value to represent the same physical amount.

Under standard international measurement guidelines, 1 Btu (IT) inch/second/sq. foot/°F converts to 1.00066922 btu (th) inches/second/sq. foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.