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Btus (IT)/hour/sq. foot/°F to Btus (th)/second/sq. foot/°F Converter (Btu/(h·ft²·°F) to Btu (th)/(s·ft²·°F))

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Live Conversion • ISO 80000-5:2019 Certified
1 BTU (IT)/hour/sq. foot/°F = 0.00027796363 BTU (th)/second/sq. foot/°F
1 Btu/(h·ft²·°F) = 0.000277964 Btu (th)/(s·ft²·°F) • 1 Btu (th)/(s·ft²·°F) = 3597.592926 Btu/(h·ft²·°F)
BTU (IT)/hour/sq. foot/°F to BTU (th)/second/sq. foot/°F: One BTU (IT)/hour/sq. foot/°F is equal to 0.00027796363 Btus (th)/second/sq. foot/°F.
Certified Authority Value
0.00027796
Btu (th)/(s·ft²·°F)
Exact: 1 Btu (th)/(s·ft²·°F) ≡ 3597.5929260061 Btu/(h·ft²·°F)
Btu/(h·ft²·°F)
Btu/(h·ft²·°F)
Swap to BTU (th)/second/sq. foot/°F to BTU (IT)/hour/sq. foot/°F
Swap to BTU (th)/second/sq. foot/°F to BTU (IT)/hour/sq. foot/°F
Btu (th)/(s·ft²·°F)
Btu (th)/(s·ft²·°F) 0.00027796363
Quick Values:
Conversion Formula
To convert BTU (IT)/hour/sq. foot/°F to BTU (th)/second/sq. foot/°F, multiply by 0.00027796363
Btu/(h·ft²·°F) × 0.00027796363 = Btu (th)/(s·ft²·°F)

Calculation: 1 Btu/(h·ft²·°F) × 0.00027796363 = 0.00027796363 Btu (th)/(s·ft²·°F)

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

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

Tap any row to calculate
BTU (IT)/hour/sq. foot/°F to BTU (th)/second/sq. foot/°F: Primary Direct Table (15 Steps)
BTU (IT)/hour/sq. foot/°F to BTU (th)/second/sq. foot/°F Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu/(h·ft²·°F) 2.779636 × 10⁻⁷ Btu (th)/(s·ft²·°F) 2.78 × 10⁻⁷
0.01 Btu/(h·ft²·°F) 2.779636 × 10⁻⁶ Btu (th)/(s·ft²·°F) 2.78 × 10⁻⁶
0.1 Btu/(h·ft²·°F) 2.779636 × 10⁻⁵ Btu (th)/(s·ft²·°F) 2.78 × 10⁻⁵
0.5 Btu/(h·ft²·°F) 0.000138982 Btu (th)/(s·ft²·°F) 1.39 × 10⁻⁴
1 Btu/(h·ft²·°F) 0.000277964 Btu (th)/(s·ft²·°F) 2.78 × 10⁻⁴
2 Btu/(h·ft²·°F) 0.000555927 Btu (th)/(s·ft²·°F) 5.559 × 10⁻⁴
5 Btu/(h·ft²·°F) 0.00138982 Btu (th)/(s·ft²·°F) 1.39 × 10⁻³
10 Btu/(h·ft²·°F) 0.00277964 Btu (th)/(s·ft²·°F) 2.78 × 10⁻³
20 Btu/(h·ft²·°F) 0.00555927 Btu (th)/(s·ft²·°F) 5.559 × 10⁻³
25 Btu/(h·ft²·°F) 0.00694909 Btu (th)/(s·ft²·°F) 6.949 × 10⁻³
50 Btu/(h·ft²·°F) 0.0138982 Btu (th)/(s·ft²·°F) 1.39 × 10⁻²
100 Btu/(h·ft²·°F) 0.0277964 Btu (th)/(s·ft²·°F) 2.78 × 10⁻²
250 Btu/(h·ft²·°F) 0.0694909 Btu (th)/(s·ft²·°F) 6.949 × 10⁻²
500 Btu/(h·ft²·°F) 0.138982 Btu (th)/(s·ft²·°F) 1.39 × 10⁻¹
1000 Btu/(h·ft²·°F) 0.277964 Btu (th)/(s·ft²·°F) 2.78 × 10⁻¹
BTU (th)/second/sq. foot/°F to BTU (IT)/hour/sq. foot/°F: Reciprocal Summary
BTU (th)/second/sq. foot/°F to BTU (IT)/hour/sq. foot/°F Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu (th)/(s·ft²·°F) 3597.592926 Btu/(h·ft²·°F) 3.598 × 10³
5 Btu (th)/(s·ft²·°F) 17987.96463 Btu/(h·ft²·°F) 1.799 × 10⁴
10 Btu (th)/(s·ft²·°F) 35975.92926 Btu/(h·ft²·°F) 3.598 × 10⁴
50 Btu (th)/(s·ft²·°F) 179879.6463 Btu/(h·ft²·°F) 1.799 × 10⁵
100 Btu (th)/(s·ft²·°F) 359759.292601 Btu/(h·ft²·°F) 3.598 × 10⁵
View Complete 15-Row BTU (th)/second/sq. foot/°F to BTU (IT)/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)/hour/sq. foot/°F (Btu/(h·ft²·°F)) and BTU (th)/second/sq. foot/°F (Btu (th)/(s·ft²·°F)):

BTU (IT)/hour/sq. foot/°F References:

  • Stationary ambient air natural free convection on vertical wall 0.880551 Btu/(h·ft²·°F)
  • Forced air breeze blowing across automotive cooling radiator 8.8055 Btu/(h·ft²·°F)
  • Liquid water forced circulation inside heat exchanger pipe 528.33 Btu/(h·ft²·°F)
  • Nucleate boiling heat transfer in pressurized steam boiler tube 2641.65 Btu/(h·ft²·°F)

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

  • Stationary ambient air natural free convection on vertical wall 0.000245 Btu (th)/(s·ft²·°F)
  • Forced air breeze blowing across automotive cooling radiator 0.002448 Btu (th)/(s·ft²·°F)
  • Liquid water forced circulation inside heat exchanger pipe 0.146857 Btu (th)/(s·ft²·°F)
  • Nucleate boiling heat transfer in pressurized steam boiler tube 0.734283 Btu (th)/(s·ft²·°F)

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

Converting BTU (IT)/hour/sq. foot/°F (Btu/(h·ft²·°F)) to BTU (th)/second/sq. 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)/hour/sq. foot/°F equals 0.000277964 BTU (th)/second/sq. foot/°F, while 1 Btu (th)/(s·ft²·°F) equals 3597.592926 Btu/(h·ft²·°F).

Direct Factor1 Btu/(h·ft²·°F) = 0.000277964 Btu (th)/(s·ft²·°F)
Inverse Ratio1 Btu (th)/(s·ft²·°F) = 3597.592926 Btu/(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 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/(h·ft²·°F) = 5.678263 watt per square meter kelvin (W/(m²·K))
2. Target SI Bridge (ktarget):1 Btu (th)/(s·ft²·°F) = 20428.08 watt per square meter kelvin (W/(m²·K))
Step-by-step substitution for BTU (IT)/hour/sq. foot/°F → BTU (th)/second/sq. foot/°F:V(Btu (th)/(s·ft²·°F)) = V(Btu/(h·ft²·°F)) × ( 5.678263 / 20428.08 ) = V(Btu/(h·ft²·°F)) × 0.000277964
Mathematical FormulaValue in BTU (th)/second/sq. foot/°F = Value in BTU (IT)/hour/sq. foot/°F × 0.00027796363Direct computational formula applied for standard conversion.
Worked Example

Converting 15 Btu/(h·ft²·°F) yields an exact output of 0.00416945 Btu (th)/(s·ft²·°F) in BTU (th)/second/sq. foot/°F. Under higher industrial throughput, 1000 Btu/(h·ft²·°F) translates to 0.277964 Btu (th)/(s·ft²·°F).

Inverse check: 1 Btu (th)/(s·ft²·°F) = 3597.592926 Btu/(h·ft²·°F).

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

BTU (IT)/hour/sq. foot/°F

Btu/(h·ft²·°F)
Imperial / US

A BTU (IT)/hour/sq. foot/°F (Btu/(h·ft²·°F)) is an imperial and US customary unit for heat transfer coefficient.

Applications & Practical Context

In practical heat transfer coefficient terms, a stationary ambient air natural free convection on vertical wall equals 0.880551 Btu/(h·ft²·°F), a forced air breeze blowing across automotive cooling radiator equals 8.8055 Btu/(h·ft²·°F), a liquid water forced circulation inside heat exchanger pipe equals 528.33 Btu/(h·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu/(h·ft²·°F) corresponds to 5.678263 W/(m²·K) in standard SI measurement.

Conversion to SI Unit: watt per square meter kelvin (W/(m²·K))
1 Btu/(h·ft²·°F) = 5.678263 W/(m²·K)

BTU (th)/second/sq. foot/°F

Btu (th)/(s·ft²·°F)
Imperial / US

A BTU (th)/second/sq. 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 stationary ambient air natural free convection on vertical wall equals 0.000245 Btu (th)/(s·ft²·°F), a forced air breeze blowing across automotive cooling radiator equals 0.002448 Btu (th)/(s·ft²·°F), a liquid water forced circulation inside heat exchanger pipe equals 0.146857 Btu (th)/(s·ft²·°F).

Physical Setup

A physical magnitude of 1 Btu (th)/(s·ft²·°F) corresponds to 20428.08 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) = 20428.08 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/(h·ft²·°F) at Forced Air Duct Cooling (ΔT = 25 K) = 141.9566 W/m²
Equals 0.142 kW/m² • 45 BTU/(h·ft²) • 0.00339057 cal/(s·cm²)
SI Heat Flux
141.9566
W/m²
Watts per Square Meter
Solar / Combustion
0.142
kW/m²
Kilowatts per Square Meter
US Building Envelope
45
BTU/(h·ft²)
BTU per Hour Sq. Foot
CGS Thermal
0.00339057
cal/(s·cm²)
Calories per Second Sq. Cm
Meteorology
0.2035
Ly/min
Langley per Minute
Furnace Flux
0.00014196
MW/m²
Megawatts per Square Meter
  1. 1. Normalize Input to SI Base Unit (W/(m²·K)):
    h = 1 Btu/(h·ft²·°F) × 5.67826333 = 5.67826333 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 = (5.67826333 W/(m²·K)) × (25 K) = 141.956583 W/m²
  4. 4. Convert to Standard Engineering Units:
    • W/m²: 141.956583 × 1 = 141.9566 W/m² (Watts per Square Meter) • kW/m²: 141.956583 × 0.001 = 0.142 kW/m² (Kilowatts per Square Meter) • BTU/(h·ft²): 141.956583 × 0.317 = 45 BTU/(h·ft²) (BTU per Hour Sq. Foot) • cal/(s·cm²): 141.956583 × 2.3885 × 10⁻⁵ = 0.00339057 cal/(s·cm²) (Calories per Second Sq. Cm) • Ly/min: 141.956583 × 0.001433 = 0.2035 Ly/min (Langley per Minute) • MW/m²: 141.956583 × 1 × 10⁻⁶ = 0.00014196 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 0.00027796363 btus (th)/second/sq. foot/°f (Btu (th)/(s·ft²·°F)) in 1 btu (it)/hour/sq. foot/°f (Btu/(h·ft²·°F)). To calculate larger amounts manually, simply multiply your total number of btus (it)/hour/sq. foot/°f by the conversion multiplier of 0.00027796363.

The mathematical formula to convert btus (it)/hour/sq. foot/°f to btus (th)/second/sq. foot/°f is: [value] * 0.00027796363 = btus (th)/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 btus (th)/second/sq. foot/°f back to btus (it)/hour/sq. foot/°f, you must divide your starting value by 0.00027796363. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (th)/second/sq. foot/°f input field.

1 BTU (th)/second/sq. foot/°F is larger than 1 BTU (IT)/hour/sq. foot/°F. Specifically, 1 BTU (IT)/hour/sq. foot/°F equals 0.00027796363 btus (th)/second/sq. foot/°f, meaning 1 BTU (th)/second/sq. foot/°F is 3597.5929 times larger than 1 BTU (IT)/hour/sq. foot/°F (a difference of 3.56 orders of magnitude). Expressing measurements in btus (it)/hour/sq. foot/°f requires a larger numerical value to represent the equivalent physical magnitude.

Under standard international measurement guidelines, 1 BTU (IT)/hour/sq. foot/°F converts to 0.00027796363 btus (th)/second/sq. foot/°f. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.