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Btus (IT)/second/square foot/°F to Btus (th)/second/square foot/°F Converter (Btu/(s·ft²·°F) to Btu (th)/(s·ft²·°F))

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Live Conversion • ISO 80000-5:2019 Certified
1 Btu (IT)/second/square foot/°F = 1.00065413 Btu (th)/second/square foot/°F
1 Btu/(s·ft²·°F) = 1.000654 Btu (th)/(s·ft²·°F) • 1 Btu (th)/(s·ft²·°F) = 0.999346 Btu/(s·ft²·°F)
Btu (IT)/second/square foot/°F to Btu (th)/second/square foot/°F: One Btu (IT)/second/square foot/°F is equal to 1.00065413 Btus (th)/second/square foot/°F.
Certified Authority Value
1.00065413
Btu (th)/(s·ft²·°F)
Exact: 1 Btu (th)/(s·ft²·°F) ≡ 0.9993462984 Btu/(s·ft²·°F)
Btu/(s·ft²·°F)
Btu/(s·ft²·°F)
Btu (th)/(s·ft²·°F)
Btu (th)/(s·ft²·°F) 1.00065413
Quick Values:
Conversion Formula
To convert Btu (IT)/second/square foot/°F to Btu (th)/second/square foot/°F, multiply by 1.00065413
Btu/(s·ft²·°F) × 1.00065413 = Btu (th)/(s·ft²·°F)

Calculation: 1 Btu/(s·ft²·°F) × 1.00065413 = 1.00065413 Btu (th)/(s·ft²·°F)

Common Btu (IT)/second/square foot/°F to Btu (th)/second/square foot/°F Calculations

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

Tap any row to calculate
Btu (IT)/second/square foot/°F to Btu (th)/second/square foot/°F: Primary Direct Table (15 Steps)
Btu (IT)/second/square foot/°F to Btu (th)/second/square foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu/(s·ft²·°F) 0.00100065 Btu (th)/(s·ft²·°F) 1.001 × 10⁻³
0.01 Btu/(s·ft²·°F) 0.0100065 Btu (th)/(s·ft²·°F) 1.001 × 10⁻²
0.1 Btu/(s·ft²·°F) 0.100065 Btu (th)/(s·ft²·°F) 1.001 × 10⁻¹
0.5 Btu/(s·ft²·°F) 0.500327 Btu (th)/(s·ft²·°F) 5.003 × 10⁻¹
1 Btu/(s·ft²·°F) 1.000654 Btu (th)/(s·ft²·°F) 1.001 × 10⁰
2 Btu/(s·ft²·°F) 2.001308 Btu (th)/(s·ft²·°F) 2.001 × 10⁰
5 Btu/(s·ft²·°F) 5.003271 Btu (th)/(s·ft²·°F) 5.003 × 10⁰
10 Btu/(s·ft²·°F) 10.006541 Btu (th)/(s·ft²·°F) 1.001 × 10¹
20 Btu/(s·ft²·°F) 20.013083 Btu (th)/(s·ft²·°F) 2.001 × 10¹
25 Btu/(s·ft²·°F) 25.016353 Btu (th)/(s·ft²·°F) 2.502 × 10¹
50 Btu/(s·ft²·°F) 50.032706 Btu (th)/(s·ft²·°F) 5.003 × 10¹
100 Btu/(s·ft²·°F) 100.065413 Btu (th)/(s·ft²·°F) 1.001 × 10²
250 Btu/(s·ft²·°F) 250.163532 Btu (th)/(s·ft²·°F) 2.502 × 10²
500 Btu/(s·ft²·°F) 500.327065 Btu (th)/(s·ft²·°F) 5.003 × 10²
1000 Btu/(s·ft²·°F) 1000.654129 Btu (th)/(s·ft²·°F) 1.001 × 10³
Btu (th)/second/square foot/°F to Btu (IT)/second/square foot/°F: Reciprocal Summary
Btu (th)/second/square foot/°F to Btu (IT)/second/square foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu (th)/(s·ft²·°F) 0.999346 Btu/(s·ft²·°F) 9.993 × 10⁻¹
5 Btu (th)/(s·ft²·°F) 4.996731 Btu/(s·ft²·°F) 4.997 × 10⁰
10 Btu (th)/(s·ft²·°F) 9.993463 Btu/(s·ft²·°F) 9.993 × 10⁰
50 Btu (th)/(s·ft²·°F) 49.967315 Btu/(s·ft²·°F) 4.997 × 10¹
100 Btu (th)/(s·ft²·°F) 99.93463 Btu/(s·ft²·°F) 9.993 × 10¹

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)/second/square foot/°F (Btu/(s·ft²·°F)) and Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)):

Btu (IT)/second/square foot/°F References:

  • Liquid rocket regenerative cooling jacket convective coefficient 0.2 Btu/(s·ft²·°F)

Btu (th)/second/square foot/°F References:

  • High-pressure steam boiler water-wall tube boiling coefficient 0.5 Btu (th)/(s·ft²·°F)
ISQ Dimension: [M T⁻³ Θ⁻¹] Coherent SI Unit: watt per square meter kelvin (W/(m²·K)) Thermodynamics & Heat Transfer

How to Convert Btu (IT)/second/square foot/°F to Btu (th)/second/square foot/°F

Converting Btu (IT)/second/square foot/°F (Btu/(s·ft²·°F)) to Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) is a core calculation in Heat Transfer Coefficient, which quantifies the proportionality constant between the heat flux and the thermodynamic driving temperature difference. 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)/second/square foot/°F equals 1.000654 Btu (th)/second/square foot/°F, while 1 Btu (th)/(s·ft²·°F) equals 0.999346 Btu/(s·ft²·°F).

Direct Factor1 Btu/(s·ft²·°F) = 1.000654 Btu (th)/(s·ft²·°F)
Inverse Ratio1 Btu (th)/(s·ft²·°F) = 0.999346 Btu/(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 square meter kelvin (W/(m²·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/(s·ft²·°F) = 20441.537204 watt per square meter kelvin (W/(m²·K))
2. Target SI Bridge (ktarget):1 Btu (th)/(s·ft²·°F) = 20428.174538 watt per square meter kelvin (W/(m²·K))
Step-by-step substitution for Btu (IT)/second/square foot/°F → Btu (th)/second/square foot/°F:V(Btu (th)/(s·ft²·°F)) = V(Btu/(s·ft²·°F)) × ( 20441.537204 / 20428.174538 ) = V(Btu/(s·ft²·°F)) × 1.000654
Mathematical FormulaValue in Btu (th)/second/square foot/°F = Value in Btu (IT)/second/square foot/°F × 1.00065413Direct computational formula applied for standard conversion.
Worked Example

Evaluating an input of 120 Btu (IT)/second/square foot/°F (Btu/(s·ft²·°F)) produces 120.078496 Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)). In heavy-duty utility and industrial workloads, 10000 Btu/(s·ft²·°F) equals 10006.541292 Btu (th)/(s·ft²·°F).

Inverse check: 1 Btu (th)/(s·ft²·°F) = 0.999346 Btu/(s·ft²·°F).

Understanding Btu (IT)/second/square foot/°F and Btu (th)/second/square foot/°F

Btu (IT)/second/square foot/°F

Btu/(s·ft²·°F)
Imperial / US

A Btu (IT)/second/square foot/°F (Btu/(s·ft²·°F)) is an imperial and US customary unit for heat transfer coefficient.

Applications & Practical Context

In practical heat transfer coefficient terms, a liquid rocket regenerative cooling jacket convective coefficient equals 0.2 Btu/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu/(s·ft²·°F) corresponds to 20441.537204 W/(m²·K) in standard SI measurement.

Conversion to SI Unit: watt per square meter kelvin (W/(m²·K))
1 Btu/(s·ft²·°F) = 20441.537204 W/(m²·K)

Btu (th)/second/square foot/°F

Btu (th)/(s·ft²·°F)
Imperial / US

A Btu (th)/second/square foot/°F (Btu (th)/(s·ft²·°F)) is an imperial and US customary unit for heat transfer coefficient.

Applications & Practical Context

In practical heat transfer coefficient terms, a high-pressure steam boiler water-wall tube boiling coefficient equals 0.5 Btu (th)/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu (th)/(s·ft²·°F) corresponds to 20428.174538 W/(m²·K) in standard SI measurement.

Conversion to SI Unit: watt per square meter kelvin (W/(m²·K))
1 Btu (th)/(s·ft²·°F) = 20428.174538 W/(m²·K)

Domain Metrology & Engineering Applications

Governing Law & Equation

Newton's Law of Cooling (q = h · ΔT)

Measurement Instrumentation

Rigorously quantified in laboratory and field settings using surface heat flux transducer plates coupled with surface RTD arrays, and wind tunnel boundary layer calorimeters.

Primary Industry Sectors

Applied across industrial heat exchanger rating, nuclear reactor cooling loop simulation, electronics forced-air cooling, and architectural U-value certification under international metrology standard ISO 80000-5:2019, ASME PTC.

Institutional Metrology & Standard Authority:

Formulas, conversion coefficients, and base definitions on this page strictly adhere to the ISO 80000-5:2019, ASME PTC and the BIPM SI Brochure (9th Edition). Governed by Newton's Law of Cooling (q = h · ΔT) under ISO 80000 dimensional vector [M T⁻³ Θ⁻¹].

Multi-Variable Engineering Bridge Convective Thermodynamics & Cooling

Heat Transfer Coefficient to Convective Flux Bridge (W/m² • kW/m² • BTU/(h·ft²) • cal/(s·cm²))

Calculate Newton’s law of cooling convective heat flux q" = h × ΔT across convective film temperature drops, bridging heat transfer coefficient [M T⁻³ Θ⁻¹] with heat flux [M T⁻³].

q" = h × ΔT
Vector: [W/(m²·K)] × [K] → [W/m²]
Live Calculated Bridge Equivalent:
1 Btu/(s·ft²·°F) at Forced Air Duct Cooling (ΔT = 25 K) = 511038.4301 W/m²
Equals 511.0384 kW/m² • 161998.3626 BTU/(h·ft²) • 12.205943 cal/(s·cm²)
SI Heat Flux
511038.4301
W/m²
Watts per Square Meter
Solar / Combustion
511.0384
kW/m²
Kilowatts per Square Meter
US Building Envelope
161998.3626
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
12.205943
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
732.4884
Ly/min
Langley per Minute
Furnace Flux
0.511038
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m²·K)):
    h = 1 Btu/(s·ft²·°F) × 20441.5372036 = 20441.5372036 W/(m²·K)
  2. 2. Apply Engineering Parameter (ΔT):
    Selected condition: Forced Air Duct Cooling (ΔT = 25 K) at ΔT = 25 K
  3. 3. Execute Governing Physical Law in SI Units:
    q" = h × ΔT = (20441.5372036 W/(m²·K)) × (25 K) = 511038.43009 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 511038.43009 × 1 = 511038.4301 W/m² (Watts per Square Meter) • kW/m²: 511038.43009 × 0.001 = 511.0384 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 511038.43009 × 0.317 = 161998.3626 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 511038.43009 × 2.3885 × 10⁻⁵ = 12.205943 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 511038.43009 × 0.001433 = 732.4884 Ly/min (Langley per Minute) • MW/m²: 511038.43009 × 1 × 10⁻⁶ = 0.511038 MW/m² (Megawatts per Square Meter)
Explore Full Heat Flux Density Converter →
Engineering Substance / Operating Standard Parameter Value (K) Reference State / Condition Typical Industrial & Engineering Application
Natural Air Convection (ΔT = 15 K) 15 ΔT = 15 K (15°C) Still room air room heating surface delta
Forced Air Duct Cooling (ΔT = 25 K) 25 ΔT = 25 K (25°C) Forced fan ventilation heatsink airflow
Forced Liquid Water Cooling (ΔT = 30 K) 30 ΔT = 30 K Pumped liquid cold plate or engine jacket
Nucleate Boiling Heat Transfer (ΔT = 50 K) 50 ΔT = 50 K Boiler evaporator tube wall boundary
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Frequently Asked Questions

There are exactly 1.00065413 btus (th)/second/square foot/°f (Btu (th)/(s·ft²·°F)) in 1 btu (it)/second/square foot/°f (Btu/(s·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btus (it)/second/square foot/°f by the conversion multiplier of 1.00065413.

The mathematical formula to convert btus (it)/second/square foot/°f to btus (th)/second/square foot/°f is: [value] * 1.00065413 = btus (th)/second/square 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 btus (th)/second/square foot/°f back to btus (it)/second/square foot/°f, you must divide your starting value by 1.00065413. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (th)/second/square foot/°f input field.

1 Btu (IT)/second/square foot/°F is larger than 1 Btu (th)/second/square foot/°F. Specifically, 1 Btu (IT)/second/square foot/°F equals exactly 1.00065413 btus (th)/second/square foot/°f, making it 1.0007 times larger (a difference of 0.00 orders of magnitude). Therefore, quantities expressed in btus (th)/second/square foot/°f require a larger numerical value to represent the same physical amount.

Under standard international measurement guidelines, 1 Btu (IT)/second/square foot/°F converts to 1.00065413 btus (th)/second/square foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.