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Btu (it) Inches/hour/sq. foot/°F to Btu (th) Feet/hour/sq. foot/°F Converter (Btu·in/(h·ft²·°F) to Btu (th)·ft/(h·ft²·°F))

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Live Conversion • ISO 80000-5:2019 Certified
1 BTU (IT) inch/hour/sq. foot/°F = 0.083389118 BTU (th) foot/hour/sq. foot/°F
1 Btu·in/(h·ft²·°F) = 0.0833891 Btu (th)·ft/(h·ft²·°F) • 1 Btu (th)·ft/(h·ft²·°F) = 11.991972 Btu·in/(h·ft²·°F)
BTU (IT) inch/hour/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F: One BTU (IT) inch/hour/sq. foot/°F is equal to 0.083389118 Btu (th) Feet/hour/sq. foot/°F.
Certified Authority Value
0.08338912
Btu (th)·ft/(h·ft²·°F)
Exact: 1 Btu (th)·ft/(h·ft²·°F) ≡ 11.991972427 Btu·in/(h·ft²·°F)
Btu·in/(h·ft²·°F)
Btu·in/(h·ft²·°F)
Btu (th)·ft/(h·ft²·°F)
Btu (th)·ft/(h·ft²·°F) 0.083389118
Quick Values:
Conversion Formula
To convert BTU (IT) inch/hour/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F, multiply by 0.083389118
Btu·in/(h·ft²·°F) × 0.083389118 = Btu (th)·ft/(h·ft²·°F)

Calculation: 1 Btu·in/(h·ft²·°F) × 0.083389118 = 0.083389118 Btu (th)·ft/(h·ft²·°F)

Common BTU (IT) inch/hour/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F Calculations

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

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BTU (IT) inch/hour/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F: Primary Direct Table (15 Steps)
BTU (IT) inch/hour/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu·in/(h·ft²·°F) 8.338912 × 10⁻⁵ Btu (th)·ft/(h·ft²·°F) 8.339 × 10⁻⁵
0.01 Btu·in/(h·ft²·°F) 0.000833891 Btu (th)·ft/(h·ft²·°F) 8.339 × 10⁻⁴
0.1 Btu·in/(h·ft²·°F) 0.00833891 Btu (th)·ft/(h·ft²·°F) 8.339 × 10⁻³
0.5 Btu·in/(h·ft²·°F) 0.0416946 Btu (th)·ft/(h·ft²·°F) 4.169 × 10⁻²
1 Btu·in/(h·ft²·°F) 0.0833891 Btu (th)·ft/(h·ft²·°F) 8.339 × 10⁻²
2 Btu·in/(h·ft²·°F) 0.166778 Btu (th)·ft/(h·ft²·°F) 1.668 × 10⁻¹
5 Btu·in/(h·ft²·°F) 0.416946 Btu (th)·ft/(h·ft²·°F) 4.169 × 10⁻¹
10 Btu·in/(h·ft²·°F) 0.833891 Btu (th)·ft/(h·ft²·°F) 8.339 × 10⁻¹
20 Btu·in/(h·ft²·°F) 1.667782 Btu (th)·ft/(h·ft²·°F) 1.668 × 10⁰
25 Btu·in/(h·ft²·°F) 2.084728 Btu (th)·ft/(h·ft²·°F) 2.085 × 10⁰
50 Btu·in/(h·ft²·°F) 4.169456 Btu (th)·ft/(h·ft²·°F) 4.169 × 10⁰
100 Btu·in/(h·ft²·°F) 8.338912 Btu (th)·ft/(h·ft²·°F) 8.339 × 10⁰
250 Btu·in/(h·ft²·°F) 20.847279 Btu (th)·ft/(h·ft²·°F) 2.085 × 10¹
500 Btu·in/(h·ft²·°F) 41.694559 Btu (th)·ft/(h·ft²·°F) 4.169 × 10¹
1000 Btu·in/(h·ft²·°F) 83.389118 Btu (th)·ft/(h·ft²·°F) 8.339 × 10¹
BTU (th) foot/hour/sq. foot/°F to BTU (IT) inch/hour/sq. foot/°F: Reciprocal Summary

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/hour/sq. foot/°F (Btu·in/(h·ft²·°F)) and BTU (th) foot/hour/sq. foot/°F (Btu (th)·ft/(h·ft²·°F)):

BTU (IT) inch/hour/sq. foot/°F References:

  • Stationary atmospheric dry air thermal conductivity at sea level 0.18027 Btu·in/(h·ft²·°F)
  • Commercial fiberglass building insulation batt thermal conductivity 0.277339 Btu·in/(h·ft²·°F)
  • Liquid drinking water thermal conductivity at room temperature 4.1601 Btu·in/(h·ft²·°F)
  • Architectural structural concrete wall thermal conductivity 10.4002 Btu·in/(h·ft²·°F)

BTU (th) foot/hour/sq. foot/°F References:

  • Stationary atmospheric dry air thermal conductivity at sea level 0.015033 Btu (th)·ft/(h·ft²·°F)
  • Commercial fiberglass building insulation batt thermal conductivity 0.023127 Btu (th)·ft/(h·ft²·°F)
  • Liquid drinking water thermal conductivity at room temperature 0.346906 Btu (th)·ft/(h·ft²·°F)
  • Architectural structural concrete wall thermal conductivity 0.867264 Btu (th)·ft/(h·ft²·°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/hour/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F

Converting BTU (IT) inch/hour/sq. foot/°F (Btu·in/(h·ft²·°F)) to BTU (th) foot/hour/sq. foot/°F (Btu (th)·ft/(h·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/hour/sq. foot/°F equals 0.0833891 BTU (th) foot/hour/sq. foot/°F, while 1 Btu (th)·ft/(h·ft²·°F) equals 11.991972 Btu·in/(h·ft²·°F).

Direct Factor1 Btu·in/(h·ft²·°F) = 0.0833891 Btu (th)·ft/(h·ft²·°F)
Inverse Ratio1 Btu (th)·ft/(h·ft²·°F) = 11.991972 Btu·in/(h·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/(h·ft²·°F) = 0.144228 watt per meter kelvin (W/(m·K))
2. Target SI Bridge (ktarget):1 Btu (th)·ft/(h·ft²·°F) = 1.729577 watt per meter kelvin (W/(m·K))
Step-by-step substitution for BTU (IT) inch/hour/sq. foot/°F → BTU (th) foot/hour/sq. foot/°F:V(Btu (th)·ft/(h·ft²·°F)) = V(Btu·in/(h·ft²·°F)) × ( 0.144228 / 1.729577 ) = V(Btu·in/(h·ft²·°F)) × 0.0833891
Mathematical FormulaValue in BTU (th) foot/hour/sq. foot/°F = Value in BTU (IT) inch/hour/sq. foot/°F × 0.083389118Direct computational formula applied for standard conversion.
Worked Example

Evaluating an input of 50 BTU (IT) inch/hour/sq. foot/°F (Btu·in/(h·ft²·°F)) produces 4.169456 BTU (th) foot/hour/sq. foot/°F (Btu (th)·ft/(h·ft²·°F)). In heavy-duty utility and industrial workloads, 1000 Btu·in/(h·ft²·°F) equals 83.389118 Btu (th)·ft/(h·ft²·°F).

Inverse check: 1 Btu (th)·ft/(h·ft²·°F) = 11.991972 Btu·in/(h·ft²·°F).

Understanding BTU (IT) inch/hour/sq. foot/°F and BTU (th) foot/hour/sq. foot/°F

BTU (IT) inch/hour/sq. foot/°F

Btu·in/(h·ft²·°F)
Imperial / US

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

Applications & Practical Context

In practical thermal conductivity terms, a stationary atmospheric dry air thermal conductivity at sea level equals 0.18027 Btu·in/(h·ft²·°F), a commercial fiberglass building insulation batt thermal conductivity equals 0.277339 Btu·in/(h·ft²·°F), a liquid drinking water thermal conductivity at room temperature equals 4.1601 Btu·in/(h·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu·in/(h·ft²·°F) corresponds to 0.144228 W/(m·K) in standard SI measurement.

Conversion to SI Unit: watt per meter kelvin (W/(m·K))
1 Btu·in/(h·ft²·°F) = 0.144228 W/(m·K)

BTU (th) foot/hour/sq. foot/°F

Btu (th)·ft/(h·ft²·°F)
Imperial / US

A BTU (th) foot/hour/sq. foot/°F (Btu (th)·ft/(h·ft²·°F)) is an imperial and US customary unit for thermal conductivity.

Applications & Practical Context

In practical thermal conductivity terms, a stationary atmospheric dry air thermal conductivity at sea level equals 0.015033 Btu (th)·ft/(h·ft²·°F), a commercial fiberglass building insulation batt thermal conductivity equals 0.023127 Btu (th)·ft/(h·ft²·°F), a liquid drinking water thermal conductivity at room temperature equals 0.346906 Btu (th)·ft/(h·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu (th)·ft/(h·ft²·°F) corresponds to 1.729577 W/(m·K) in standard SI measurement.

Conversion to SI Unit: watt per meter kelvin (W/(m·K))
1 Btu (th)·ft/(h·ft²·°F) = 1.729577 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/(h·ft²·°F) at Insulated Wall Core (20K across 0.1m = 200 K/m) = 28.8456 W/m²
Equals 0.02885 kW/m² • 9.144 BTU/(h·ft²) • 0.00068896 cal/(s·cm²)
SI Heat Flux
28.8456
W/m²
Watts per Square Meter
Solar / Combustion
0.02885
kW/m²
Kilowatts per Square Meter
US Building Envelope
9.144
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
0.00068896
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
0.04135
Ly/min
Langley per Minute
Furnace Flux
2.884558 × 10⁻⁵
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m·K)):
    k = 1 Btu·in/(h·ft²·°F) × 0.1442279 = 0.1442279 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 = (0.1442279 W/(m·K)) × (200 K/m) = 28.84558 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 28.84558 × 1 = 28.8456 W/m² (Watts per Square Meter) • kW/m²: 28.84558 × 0.001 = 0.02885 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 28.84558 × 0.317 = 9.144 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 28.84558 × 2.3885 × 10⁻⁵ = 0.00068896 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 28.84558 × 0.001433 = 0.04135 Ly/min (Langley per Minute) • MW/m²: 28.84558 × 1 × 10⁻⁶ = 2.884558 × 10⁻⁵ 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 0.083389118 btu (th) feet/hour/sq. foot/°f (Btu (th)·ft/(h·ft²·°F)) in 1 btu (it) inch/hour/sq. foot/°f (Btu·in/(h·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btu (it) inches/hour/sq. foot/°f by the conversion multiplier of 0.083389118.

The mathematical formula to convert btu (it) inches/hour/sq. foot/°f to btu (th) feet/hour/sq. foot/°f is: [value] * 0.083389118 = btu (th) feet/hour/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) feet/hour/sq. foot/°f back to btu (it) inches/hour/sq. foot/°f, you must divide your starting value by 0.083389118. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (th) foot/hour/sq. foot/°f input field.

1 BTU (th) foot/hour/sq. foot/°F is larger than 1 BTU (IT) inch/hour/sq. foot/°F. Specifically, 1 BTU (IT) inch/hour/sq. foot/°F equals 0.083389118 btu (th) feet/hour/sq. foot/°f, meaning 1 BTU (th) foot/hour/sq. foot/°F is 11.992 times larger than 1 BTU (IT) inch/hour/sq. foot/°F (a difference of 1.08 orders of magnitude). Expressing measurements in btu (it) inches/hour/sq. foot/°f requires a larger numerical value to represent the equivalent physical magnitude.

Under standard international measurement guidelines, 1 BTU (IT) inch/hour/sq. foot/°F converts to 0.083389118 btu (th) feet/hour/sq. foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.