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

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Live Conversion • ISO 80000-5:2019 Certified
1 Btu (IT) foot/hour/sq. foot/°F = 0.0033355641 Btu (th) inch/second/sq. foot/°F
1 Btu·ft/(h·ft²·°F) = 0.00333556 Btu (th)·in/(s·ft²·°F) • 1 Btu (th)·in/(s·ft²·°F) = 299.799369 Btu·ft/(h·ft²·°F)
Btu (IT) foot/hour/sq. foot/°F to Btu (th) inch/second/sq. foot/°F: One Btu (IT) foot/hour/sq. foot/°F is equal to 0.0033355641 Btu (th) Inches/second/sq. foot/°F.
Certified Authority Value
0.00333556
Btu (th)·in/(s·ft²·°F)
Exact: 1 Btu (th)·in/(s·ft²·°F) ≡ 299.7993694468 Btu·ft/(h·ft²·°F)
Btu·ft/(h·ft²·°F)
Btu·ft/(h·ft²·°F)
Swap to Btu (th) inch/second/sq. foot/°F to Btu (IT) foot/hour/sq. foot/°F
Swap to Btu (th) inch/second/sq. foot/°F to Btu (IT) foot/hour/sq. foot/°F
Btu (th)·in/(s·ft²·°F)
Btu (th)·in/(s·ft²·°F) 0.0033355641
Quick Values:
Conversion Formula
To convert Btu (IT) foot/hour/sq. foot/°F to Btu (th) inch/second/sq. foot/°F, multiply by 0.0033355641
Btu·ft/(h·ft²·°F) × 0.0033355641 = Btu (th)·in/(s·ft²·°F)

Calculation: 1 Btu·ft/(h·ft²·°F) × 0.0033355641 = 0.0033355641 Btu (th)·in/(s·ft²·°F)

Common Btu (IT) foot/hour/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) foot/hour/sq. foot/°F (Btu·ft/(h·ft²·°F)) and Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)).

Tap any row to calculate
Btu (IT) foot/hour/sq. foot/°F to Btu (th) inch/second/sq. foot/°F: Primary Direct Table (15 Steps)
Btu (IT) foot/hour/sq. foot/°F to Btu (th) inch/second/sq. foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu·ft/(h·ft²·°F) 3.335564 × 10⁻⁶ Btu (th)·in/(s·ft²·°F) 3.336 × 10⁻⁶
0.01 Btu·ft/(h·ft²·°F) 3.335564 × 10⁻⁵ Btu (th)·in/(s·ft²·°F) 3.336 × 10⁻⁵
0.1 Btu·ft/(h·ft²·°F) 0.000333556 Btu (th)·in/(s·ft²·°F) 3.336 × 10⁻⁴
0.5 Btu·ft/(h·ft²·°F) 0.00166778 Btu (th)·in/(s·ft²·°F) 1.668 × 10⁻³
1 Btu·ft/(h·ft²·°F) 0.00333556 Btu (th)·in/(s·ft²·°F) 3.336 × 10⁻³
2 Btu·ft/(h·ft²·°F) 0.00667113 Btu (th)·in/(s·ft²·°F) 6.671 × 10⁻³
5 Btu·ft/(h·ft²·°F) 0.0166778 Btu (th)·in/(s·ft²·°F) 1.668 × 10⁻²
10 Btu·ft/(h·ft²·°F) 0.0333556 Btu (th)·in/(s·ft²·°F) 3.336 × 10⁻²
20 Btu·ft/(h·ft²·°F) 0.0667113 Btu (th)·in/(s·ft²·°F) 6.671 × 10⁻²
25 Btu·ft/(h·ft²·°F) 0.0833891 Btu (th)·in/(s·ft²·°F) 8.339 × 10⁻²
50 Btu·ft/(h·ft²·°F) 0.166778 Btu (th)·in/(s·ft²·°F) 1.668 × 10⁻¹
100 Btu·ft/(h·ft²·°F) 0.333556 Btu (th)·in/(s·ft²·°F) 3.336 × 10⁻¹
250 Btu·ft/(h·ft²·°F) 0.833891 Btu (th)·in/(s·ft²·°F) 8.339 × 10⁻¹
500 Btu·ft/(h·ft²·°F) 1.667782 Btu (th)·in/(s·ft²·°F) 1.668 × 10⁰
1000 Btu·ft/(h·ft²·°F) 3.335564 Btu (th)·in/(s·ft²·°F) 3.336 × 10⁰
Btu (th) inch/second/sq. foot/°F to Btu (IT) foot/hour/sq. foot/°F: Reciprocal Summary
Btu (th) inch/second/sq. foot/°F to Btu (IT) foot/hour/sq. foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu (th)·in/(s·ft²·°F) 299.799369 Btu·ft/(h·ft²·°F) 2.998 × 10²
5 Btu (th)·in/(s·ft²·°F) 1498.996847 Btu·ft/(h·ft²·°F) 1.499 × 10³
10 Btu (th)·in/(s·ft²·°F) 2997.993694 Btu·ft/(h·ft²·°F) 2.998 × 10³
50 Btu (th)·in/(s·ft²·°F) 14989.968472 Btu·ft/(h·ft²·°F) 1.499 × 10⁴
100 Btu (th)·in/(s·ft²·°F) 29979.936945 Btu·ft/(h·ft²·°F) 2.998 × 10⁴
View Complete 15-Row Btu (th) inch/second/sq. foot/°F to Btu (IT) foot/hour/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) foot/hour/sq. foot/°F (Btu·ft/(h·ft²·°F)) and Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)):

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

  • Liquid water thermal conductivity in cooling tower systems 0.35 Btu·ft/(h·ft²·°F)
  • Standard architectural building window float glass panel 0.55 Btu·ft/(h·ft²·°F)
  • Cast aluminum automotive engine cylinder head material 120 Btu·ft/(h·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) foot/hour/sq. foot/°F to Btu (th) inch/second/sq. foot/°F

Converting Btu (IT) foot/hour/sq. foot/°F (Btu·ft/(h·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) foot/hour/sq. foot/°F equals 0.00333556 Btu (th) inch/second/sq. foot/°F, while 1 Btu (th)·in/(s·ft²·°F) equals 299.799369 Btu·ft/(h·ft²·°F).

Direct Factor1 Btu·ft/(h·ft²·°F) = 0.00333556 Btu (th)·in/(s·ft²·°F)
Inverse Ratio1 Btu (th)·in/(s·ft²·°F) = 299.799369 Btu·ft/(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·ft/(h·ft²·°F) = 1.730735 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) foot/hour/sq. foot/°F → Btu (th) inch/second/sq. foot/°F:V(Btu (th)·in/(s·ft²·°F)) = V(Btu·ft/(h·ft²·°F)) × ( 1.730735 / 518.873162 ) = V(Btu·ft/(h·ft²·°F)) × 0.00333556
Mathematical FormulaValue in Btu (th) inch/second/sq. foot/°F = Value in Btu (IT) foot/hour/sq. foot/°F × 0.0033355641Direct computational formula applied for standard conversion.
Worked Example

To convert 50 Btu (IT) foot/hour/sq. foot/°F (Btu·ft/(h·ft²·°F)) to Btu (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)): multiply 50 by 0.00333556 to get 0.166778 Btu (th)·in/(s·ft²·°F). At an industrial engineering scale, 1000 Btu·ft/(h·ft²·°F) converts to 3.335564 Btu (th)·in/(s·ft²·°F).

Inverse check: 1 Btu (th)·in/(s·ft²·°F) = 299.799369 Btu·ft/(h·ft²·°F).

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

Btu (IT) foot/hour/sq. foot/°F

Btu·ft/(h·ft²·°F)
Imperial / US

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

Applications & Practical Context

In practical thermal conductivity terms, a liquid water thermal conductivity in cooling tower systems equals 0.35 Btu·ft/(h·ft²·°F), a standard architectural building window float glass panel equals 0.55 Btu·ft/(h·ft²·°F), a cast aluminum automotive engine cylinder head material equals 120 Btu·ft/(h·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu·ft/(h·ft²·°F) corresponds to 1.730735 W/(m·K) in standard SI measurement.

Conversion to SI Unit: watt per meter kelvin (W/(m·K))
1 Btu·ft/(h·ft²·°F) = 1.730735 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·ft/(h·ft²·°F) at Insulated Wall Core (20K across 0.1m = 200 K/m) = 346.1469 W/m²
Equals 0.3461 kW/m² • 109.728 BTU/(h·ft²) • 0.00826758 cal/(s·cm²)
SI Heat Flux
346.1469
W/m²
Watts per Square Meter
Solar / Combustion
0.3461
kW/m²
Kilowatts per Square Meter
US Building Envelope
109.728
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
0.00826758
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
0.4961
Ly/min
Langley per Minute
Furnace Flux
0.00034615
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m·K)):
    k = 1 Btu·ft/(h·ft²·°F) × 1.73073467 = 1.73073467 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 = (1.73073467 W/(m·K)) × (200 K/m) = 346.146933 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 346.146933 × 1 = 346.1469 W/m² (Watts per Square Meter) • kW/m²: 346.146933 × 0.001 = 0.3461 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 346.146933 × 0.317 = 109.728 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 346.146933 × 2.3885 × 10⁻⁵ = 0.00826758 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 346.146933 × 0.001433 = 0.4961 Ly/min (Langley per Minute) • MW/m²: 346.146933 × 1 × 10⁻⁶ = 0.00034615 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 0.0033355641 btu (th) inches/second/sq. foot/°f (Btu (th)·in/(s·ft²·°F)) in 1 btu (it) foot/hour/sq. foot/°f (Btu·ft/(h·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btu (it) feet/hour/sq. foot/°f by the conversion multiplier of 0.0033355641.

The mathematical formula to convert btu (it) feet/hour/sq. foot/°f to btu (th) inches/second/sq. foot/°f is: [value] * 0.0033355641 = 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) feet/hour/sq. foot/°f, you must divide your starting value by 0.0033355641. 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 (th) inch/second/sq. foot/°F is larger than 1 Btu (IT) foot/hour/sq. foot/°F. Specifically, 1 Btu (IT) foot/hour/sq. foot/°F equals 0.0033355641 btu (th) inches/second/sq. foot/°f, meaning 1 Btu (th) inch/second/sq. foot/°F is 299.7994 times larger than 1 Btu (IT) foot/hour/sq. foot/°F (a difference of 2.48 orders of magnitude). Expressing measurements in btu (it) feet/hour/sq. foot/°f requires a larger numerical value to represent the equivalent physical magnitude.

Under standard international measurement guidelines, 1 Btu (IT) foot/hour/sq. foot/°F converts to 0.0033355641 btu (th) inches/second/sq. foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.