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

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Live Conversion • ISO 80000-5:2019 Certified
1 BTU (th) foot/hour/sq. foot/°F = 0.0033333327 BTU (th) inch/second/sq. foot/°F
1 Btu (th)·ft/(h·ft²·°F) = 0.00333333 Btu (th)·in/(s·ft²·°F) • 1 Btu (th)·in/(s·ft²·°F) = 300.000058 Btu (th)·ft/(h·ft²·°F)
BTU (th) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F: One BTU (th) foot/hour/sq. foot/°F is equal to 0.0033333327 Btu (th) Inches/second/sq. foot/°F.
Certified Authority Value
0.00333333
Btu (th)·in/(s·ft²·°F)
Exact: 1 Btu (th)·in/(s·ft²·°F) ≡ 300.0000578176 Btu (th)·ft/(h·ft²·°F)
Btu (th)·ft/(h·ft²·°F)
Btu (th)·ft/(h·ft²·°F)
Swap to BTU (th) inch/second/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F
Swap to BTU (th) inch/second/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F
Btu (th)·in/(s·ft²·°F)
Btu (th)·in/(s·ft²·°F) 0.0033333327
Quick Values:
Conversion Formula
To convert BTU (th) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F, multiply by 0.0033333327
Btu (th)·ft/(h·ft²·°F) × 0.0033333327 = Btu (th)·in/(s·ft²·°F)

Calculation: 1 Btu (th)·ft/(h·ft²·°F) × 0.0033333327 = 0.0033333327 Btu (th)·in/(s·ft²·°F)

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

Tap any row to calculate
BTU (th) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F: Primary Direct Table (15 Steps)
BTU (th) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu (th)·ft/(h·ft²·°F) 3.333333 × 10⁻⁶ Btu (th)·in/(s·ft²·°F) 3.333 × 10⁻⁶
0.01 Btu (th)·ft/(h·ft²·°F) 3.333333 × 10⁻⁵ Btu (th)·in/(s·ft²·°F) 3.333 × 10⁻⁵
0.1 Btu (th)·ft/(h·ft²·°F) 0.000333333 Btu (th)·in/(s·ft²·°F) 3.333 × 10⁻⁴
0.5 Btu (th)·ft/(h·ft²·°F) 0.00166667 Btu (th)·in/(s·ft²·°F) 1.667 × 10⁻³
1 Btu (th)·ft/(h·ft²·°F) 0.00333333 Btu (th)·in/(s·ft²·°F) 3.333 × 10⁻³
2 Btu (th)·ft/(h·ft²·°F) 0.00666667 Btu (th)·in/(s·ft²·°F) 6.667 × 10⁻³
5 Btu (th)·ft/(h·ft²·°F) 0.0166667 Btu (th)·in/(s·ft²·°F) 1.667 × 10⁻²
10 Btu (th)·ft/(h·ft²·°F) 0.0333333 Btu (th)·in/(s·ft²·°F) 3.333 × 10⁻²
20 Btu (th)·ft/(h·ft²·°F) 0.0666667 Btu (th)·in/(s·ft²·°F) 6.667 × 10⁻²
25 Btu (th)·ft/(h·ft²·°F) 0.0833333 Btu (th)·in/(s·ft²·°F) 8.333 × 10⁻²
50 Btu (th)·ft/(h·ft²·°F) 0.166667 Btu (th)·in/(s·ft²·°F) 1.667 × 10⁻¹
100 Btu (th)·ft/(h·ft²·°F) 0.333333 Btu (th)·in/(s·ft²·°F) 3.333 × 10⁻¹
250 Btu (th)·ft/(h·ft²·°F) 0.833333 Btu (th)·in/(s·ft²·°F) 8.333 × 10⁻¹
500 Btu (th)·ft/(h·ft²·°F) 1.666666 Btu (th)·in/(s·ft²·°F) 1.667 × 10⁰
1000 Btu (th)·ft/(h·ft²·°F) 3.333333 Btu (th)·in/(s·ft²·°F) 3.333 × 10⁰
BTU (th) inch/second/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F: Reciprocal Summary
BTU (th) inch/second/sq. foot/°F to BTU (th) foot/hour/sq. foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu (th)·in/(s·ft²·°F) 300.000058 Btu (th)·ft/(h·ft²·°F) 3 × 10²
5 Btu (th)·in/(s·ft²·°F) 1500.000289 Btu (th)·ft/(h·ft²·°F) 1.5 × 10³
10 Btu (th)·in/(s·ft²·°F) 3000.000578 Btu (th)·ft/(h·ft²·°F) 3 × 10³
50 Btu (th)·in/(s·ft²·°F) 15000.002891 Btu (th)·ft/(h·ft²·°F) 1.5 × 10⁴
100 Btu (th)·in/(s·ft²·°F) 30000.005782 Btu (th)·ft/(h·ft²·°F) 3 × 10⁴
View Complete 15-Row BTU (th) inch/second/sq. foot/°F to BTU (th) 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 (th) foot/hour/sq. foot/°F (Btu (th)·ft/(h·ft²·°F)) and BTU (th) inch/second/sq. foot/°F (Btu (th)·in/(s·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)

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

  • Stationary atmospheric dry air thermal conductivity at sea level 5.0E-5 Btu (th)·in/(s·ft²·°F)
  • Commercial fiberglass building insulation batt thermal conductivity 7.7E-5 Btu (th)·in/(s·ft²·°F)
  • Liquid drinking water thermal conductivity at room temperature 0.001156 Btu (th)·in/(s·ft²·°F)
  • Architectural structural concrete wall thermal conductivity 0.002891 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 (th) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F

Converting BTU (th) foot/hour/sq. foot/°F (Btu (th)·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 (th) foot/hour/sq. foot/°F equals 0.00333333 BTU (th) inch/second/sq. foot/°F, while 1 Btu (th)·in/(s·ft²·°F) equals 300.000058 Btu (th)·ft/(h·ft²·°F).

Direct Factor1 Btu (th)·ft/(h·ft²·°F) = 0.00333333 Btu (th)·in/(s·ft²·°F)
Inverse Ratio1 Btu (th)·in/(s·ft²·°F) = 300.000058 Btu (th)·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 (th)·ft/(h·ft²·°F) = 1.729577 watt per meter kelvin (W/(m·K))
2. Target SI Bridge (ktarget):1 Btu (th)·in/(s·ft²·°F) = 518.8732 watt per meter kelvin (W/(m·K))
Step-by-step substitution for BTU (th) foot/hour/sq. foot/°F → BTU (th) inch/second/sq. foot/°F:V(Btu (th)·in/(s·ft²·°F)) = V(Btu (th)·ft/(h·ft²·°F)) × ( 1.729577 / 518.8732 ) = V(Btu (th)·ft/(h·ft²·°F)) × 0.00333333
Mathematical FormulaValue in BTU (th) inch/second/sq. foot/°F = Value in BTU (th) foot/hour/sq. foot/°F × 0.0033333327Direct computational formula applied for standard conversion.
Worked Example

For an engineering input of 36 Btu (th)·ft/(h·ft²·°F), applying the conversion factor yields exactly 0.12 Btu (th)·in/(s·ft²·°F). At larger operational scale, 100 BTU (th) foot/hour/sq. foot/°F corresponds to 0.333333 Btu (th)·in/(s·ft²·°F).

Inverse check: 1 Btu (th)·in/(s·ft²·°F) = 300.000058 Btu (th)·ft/(h·ft²·°F).

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

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)

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 stationary atmospheric dry air thermal conductivity at sea level equals 5 × 10⁻⁵ Btu (th)·in/(s·ft²·°F), a commercial fiberglass building insulation batt thermal conductivity equals 7.7 × 10⁻⁵ Btu (th)·in/(s·ft²·°F), a liquid drinking water thermal conductivity at room temperature equals 0.001156 Btu (th)·in/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu (th)·in/(s·ft²·°F) corresponds to 518.8732 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) = 518.8732 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 (th)·ft/(h·ft²·°F) at Insulated Wall Core (20K across 0.1m = 200 K/m) = 345.9154 W/m²
Equals 0.3459 kW/m² • 109.6546 BTU/(h·ft²) • 0.00826205 cal/(s·cm²)
SI Heat Flux
345.9154
W/m²
Watts per Square Meter
Solar / Combustion
0.3459
kW/m²
Kilowatts per Square Meter
US Building Envelope
109.6546
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
0.00826205
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
0.4958
Ly/min
Langley per Minute
Furnace Flux
0.00034592
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m·K)):
    k = 1 Btu (th)·ft/(h·ft²·°F) × 1.729577 = 1.729577 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 = (1.729577 W/(m·K)) × (200 K/m) = 345.9154 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 345.9154 × 1 = 345.9154 W/m² (Watts per Square Meter) • kW/m²: 345.9154 × 0.001 = 0.3459 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 345.9154 × 0.317 = 109.6546 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 345.9154 × 2.3885 × 10⁻⁵ = 0.00826205 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 345.9154 × 0.001433 = 0.4958 Ly/min (Langley per Minute) • MW/m²: 345.9154 × 1 × 10⁻⁶ = 0.00034592 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 0.0033333327 btu (th) inches/second/sq. foot/°f (Btu (th)·in/(s·ft²·°F)) in 1 btu (th) foot/hour/sq. foot/°f (Btu (th)·ft/(h·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btu (th) feet/hour/sq. foot/°f by the conversion multiplier of 0.0033333327.

The mathematical formula to convert btu (th) feet/hour/sq. foot/°f to btu (th) inches/second/sq. foot/°f is: [value] * 0.0033333327 = 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 (th) feet/hour/sq. foot/°f, you must divide your starting value by 0.0033333327. 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 (th) foot/hour/sq. foot/°F. Specifically, 1 BTU (th) foot/hour/sq. foot/°F equals 0.0033333327 btu (th) inches/second/sq. foot/°f, meaning 1 BTU (th) inch/second/sq. foot/°F is 300.0001 times larger than 1 BTU (th) foot/hour/sq. foot/°F (a difference of 2.48 orders of magnitude). Expressing measurements in btu (th) feet/hour/sq. foot/°f requires a larger numerical value to represent the equivalent physical magnitude.

Under standard international measurement guidelines, 1 BTU (th) foot/hour/sq. foot/°F converts to 0.0033333327 btu (th) inches/second/sq. foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.