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

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Live Conversion • ISO 80000-5:2019 Certified
1 BTU (th) inch/second/sq. foot/°F = 299.79933381 BTU (IT) foot/hour/sq. foot/°F
1 Btu (th)·in/(s·ft²·°F) = 299.799334 Btu·ft/(h·ft²·°F) • 1 Btu·ft/(h·ft²·°F) = 0.00333556 Btu (th)·in/(s·ft²·°F)
BTU (th) inch/second/sq. foot/°F to BTU (IT) foot/hour/sq. foot/°F: One BTU (th) inch/second/sq. foot/°F is equal to 299.79933381 Btu (it) Feet/hour/sq. foot/°F.
Certified Authority Value
299.79933381
Btu·ft/(h·ft²·°F)
Exact: 1 Btu·ft/(h·ft²·°F) ≡ 0.00333556445 Btu (th)·in/(s·ft²·°F)
Btu (th)·in/(s·ft²·°F)
Btu (th)·in/(s·ft²·°F)
Swap to BTU (IT) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F
Swap to BTU (IT) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F
Btu·ft/(h·ft²·°F)
Btu·ft/(h·ft²·°F) 299.79933381
Quick Values:
Conversion Formula
To convert BTU (th) inch/second/sq. foot/°F to BTU (IT) foot/hour/sq. foot/°F, multiply by 299.79933381
Btu (th)·in/(s·ft²·°F) × 299.79933381 = Btu·ft/(h·ft²·°F)

Calculation: 1 Btu (th)·in/(s·ft²·°F) × 299.79933381 = 299.79933381 Btu·ft/(h·ft²·°F)

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

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

Tap any row to calculate
BTU (th) inch/second/sq. foot/°F to BTU (IT) foot/hour/sq. foot/°F: Primary Direct Table (15 Steps)
BTU (th) inch/second/sq. foot/°F to BTU (IT) foot/hour/sq. foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu (th)·in/(s·ft²·°F) 0.299799 Btu·ft/(h·ft²·°F) 2.998 × 10⁻¹
0.01 Btu (th)·in/(s·ft²·°F) 2.997993 Btu·ft/(h·ft²·°F) 2.998 × 10⁰
0.1 Btu (th)·in/(s·ft²·°F) 29.979933 Btu·ft/(h·ft²·°F) 2.998 × 10¹
0.5 Btu (th)·in/(s·ft²·°F) 149.899667 Btu·ft/(h·ft²·°F) 1.499 × 10²
1 Btu (th)·in/(s·ft²·°F) 299.799334 Btu·ft/(h·ft²·°F) 2.998 × 10²
2 Btu (th)·in/(s·ft²·°F) 599.598668 Btu·ft/(h·ft²·°F) 5.996 × 10²
5 Btu (th)·in/(s·ft²·°F) 1498.996669 Btu·ft/(h·ft²·°F) 1.499 × 10³
10 Btu (th)·in/(s·ft²·°F) 2997.993338 Btu·ft/(h·ft²·°F) 2.998 × 10³
20 Btu (th)·in/(s·ft²·°F) 5995.986676 Btu·ft/(h·ft²·°F) 5.996 × 10³
25 Btu (th)·in/(s·ft²·°F) 7494.983345 Btu·ft/(h·ft²·°F) 7.495 × 10³
50 Btu (th)·in/(s·ft²·°F) 14989.96669 Btu·ft/(h·ft²·°F) 1.499 × 10⁴
100 Btu (th)·in/(s·ft²·°F) 29979.933381 Btu·ft/(h·ft²·°F) 2.998 × 10⁴
250 Btu (th)·in/(s·ft²·°F) 74949.833452 Btu·ft/(h·ft²·°F) 7.495 × 10⁴
500 Btu (th)·in/(s·ft²·°F) 149899.666905 Btu·ft/(h·ft²·°F) 1.499 × 10⁵
1000 Btu (th)·in/(s·ft²·°F) 299799.333809 Btu·ft/(h·ft²·°F) 2.998 × 10⁵
BTU (IT) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F: Reciprocal Summary
BTU (IT) foot/hour/sq. foot/°F to BTU (th) inch/second/sq. foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu·ft/(h·ft²·°F) 0.00333556 Btu (th)·in/(s·ft²·°F) 3.336 × 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
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
View Complete 15-Row BTU (IT) foot/hour/sq. foot/°F to BTU (th) 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 (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)) and BTU (IT) foot/hour/sq. foot/°F (Btu·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)

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

  • Stationary atmospheric dry air thermal conductivity at sea level 0.015023 Btu·ft/(h·ft²·°F)
  • Commercial fiberglass building insulation batt thermal conductivity 0.023112 Btu·ft/(h·ft²·°F)
  • Liquid drinking water thermal conductivity at room temperature 0.346674 Btu·ft/(h·ft²·°F)
  • Architectural structural concrete wall thermal conductivity 0.866684 Btu·ft/(h·ft²·°F)

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

Converting BTU (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)) to BTU (IT) foot/hour/sq. foot/°F (Btu·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 (th) inch/second/sq. foot/°F equals 299.799334 BTU (IT) foot/hour/sq. foot/°F, while 1 Btu·ft/(h·ft²·°F) equals 0.00333556 Btu (th)·in/(s·ft²·°F).

Direct Factor1 Btu (th)·in/(s·ft²·°F) = 299.799334 Btu·ft/(h·ft²·°F)
Inverse Ratio1 Btu·ft/(h·ft²·°F) = 0.00333556 Btu (th)·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 (th)·in/(s·ft²·°F) = 518.8732 watt per meter kelvin (W/(m·K))
2. Target SI Bridge (ktarget):1 Btu·ft/(h·ft²·°F) = 1.730735 watt per meter kelvin (W/(m·K))
Step-by-step substitution for BTU (th) inch/second/sq. foot/°F → BTU (IT) foot/hour/sq. foot/°F:V(Btu·ft/(h·ft²·°F)) = V(Btu (th)·in/(s·ft²·°F)) × ( 518.8732 / 1.730735 ) = V(Btu (th)·in/(s·ft²·°F)) × 299.799334
Mathematical FormulaValue in BTU (IT) foot/hour/sq. foot/°F = Value in BTU (th) inch/second/sq. foot/°F × 299.79933381Direct computational formula applied for standard conversion.
Worked Example

Evaluating an input of 2.5 BTU (th) inch/second/sq. foot/°F (Btu (th)·in/(s·ft²·°F)) produces 749.498335 BTU (IT) foot/hour/sq. foot/°F (Btu·ft/(h·ft²·°F)). In heavy-duty utility and industrial workloads, 1000 Btu (th)·in/(s·ft²·°F) equals 299799.333809 Btu·ft/(h·ft²·°F).

Inverse check: 1 Btu·ft/(h·ft²·°F) = 0.00333556 Btu (th)·in/(s·ft²·°F).

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

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)

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 stationary atmospheric dry air thermal conductivity at sea level equals 0.015023 Btu·ft/(h·ft²·°F), a commercial fiberglass building insulation batt thermal conductivity equals 0.023112 Btu·ft/(h·ft²·°F), a liquid drinking water thermal conductivity at room temperature equals 0.346674 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)

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)·in/(s·ft²·°F) at Insulated Wall Core (20K across 0.1m = 200 K/m) = 103774.64 W/m²
Equals 103.7746 kW/m² • 32896.3944 BTU/(h·ft²) • 2.478615 cal/(s·cm²)
SI Heat Flux
103774.64
W/m²
Watts per Square Meter
Solar / Combustion
103.7746
kW/m²
Kilowatts per Square Meter
US Building Envelope
32896.3944
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
2.478615
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
148.7436
Ly/min
Langley per Minute
Furnace Flux
0.103775
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m·K)):
    k = 1 Btu (th)·in/(s·ft²·°F) × 518.8732 = 518.8732 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 = (518.8732 W/(m·K)) × (200 K/m) = 103774.64 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 103774.64 × 1 = 103774.64 W/m² (Watts per Square Meter) • kW/m²: 103774.64 × 0.001 = 103.7746 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 103774.64 × 0.317 = 32896.3944 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 103774.64 × 2.3885 × 10⁻⁵ = 2.478615 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 103774.64 × 0.001433 = 148.7436 Ly/min (Langley per Minute) • MW/m²: 103774.64 × 1 × 10⁻⁶ = 0.103775 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 299.79933381 btu (it) feet/hour/sq. foot/°f (Btu·ft/(h·ft²·°F)) in 1 btu (th) inch/second/sq. foot/°f (Btu (th)·in/(s·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btu (th) inches/second/sq. foot/°f by the conversion multiplier of 299.79933381.

The mathematical formula to convert btu (th) inches/second/sq. foot/°f to btu (it) feet/hour/sq. foot/°f is: [value] * 299.79933381 = btu (it) 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 (it) feet/hour/sq. foot/°f back to btu (th) inches/second/sq. foot/°f, you must divide your starting value by 299.79933381. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (it) foot/hour/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 (th) inch/second/sq. foot/°F equals exactly 299.79933381 btu (it) feet/hour/sq. foot/°f, making it 299.7993 times larger (a difference of 2.48 orders of magnitude). Therefore, quantities expressed in btu (it) feet/hour/sq. foot/°f require a larger numerical value to represent the same physical amount.

Under standard international measurement guidelines, 1 BTU (th) inch/second/sq. foot/°F converts to 299.79933381 btu (it) feet/hour/sq. foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.