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Btus (IT)/hour/square foot to Btus (IT)/second/square foot Converter (Btu/(h·ft²) to Btu/(s·ft²))

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Live Conversion • ISO 80000-5:2019 Certified
1 Btu (IT)/hour/square foot = 0.00027777778 Btu (IT)/second/square foot
1 Btu/(h·ft²) = 0.000277778 Btu/(s·ft²) • 1 Btu/(s·ft²) = 3,600 Btu/(h·ft²)
Btu (IT)/hour/square foot to Btu (IT)/second/square foot: One Btu (IT)/hour/square foot is equal to 0.00027777778 Btus (IT)/second/square foot.
Certified Authority Value
0.00027778
Btu/(s·ft²)
Exact: 1 Btu/(s·ft²) ≡ 3600 Btu/(h·ft²)
Btu/(h·ft²)
Btu/(h·ft²)
Swap to Btu (IT)/second/square foot to Btu (IT)/hour/square foot
Swap to Btu (IT)/second/square foot to Btu (IT)/hour/square foot
Btu/(s·ft²)
Btu/(s·ft²) 0.00027777778
Quick Values:
Conversion Formula
To convert Btu (IT)/hour/square foot to Btu (IT)/second/square foot, multiply by 0.00027777778
Btu/(h·ft²) × 0.00027777778 = Btu/(s·ft²)

Calculation: 1 Btu/(h·ft²) × 0.00027777778 = 0.00027777778 Btu/(s·ft²)

Common Btu (IT)/hour/square foot to Btu (IT)/second/square foot Calculations

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

Tap any row to calculate
Btu (IT)/hour/square foot to Btu (IT)/second/square foot: Primary Direct Table (15 Steps)
Btu (IT)/hour/square foot to Btu (IT)/second/square foot Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu/(h·ft²) 2.777778 × 10⁻⁷ Btu/(s·ft²) 2.778 × 10⁻⁷
0.01 Btu/(h·ft²) 2.777778 × 10⁻⁶ Btu/(s·ft²) 2.778 × 10⁻⁶
0.1 Btu/(h·ft²) 2.777778 × 10⁻⁵ Btu/(s·ft²) 2.778 × 10⁻⁵
0.5 Btu/(h·ft²) 0.000138889 Btu/(s·ft²) 1.389 × 10⁻⁴
1 Btu/(h·ft²) 0.000277778 Btu/(s·ft²) 2.778 × 10⁻⁴
2 Btu/(h·ft²) 0.000555556 Btu/(s·ft²) 5.556 × 10⁻⁴
5 Btu/(h·ft²) 0.00138889 Btu/(s·ft²) 1.389 × 10⁻³
10 Btu/(h·ft²) 0.00277778 Btu/(s·ft²) 2.778 × 10⁻³
20 Btu/(h·ft²) 0.00555556 Btu/(s·ft²) 5.556 × 10⁻³
25 Btu/(h·ft²) 0.00694444 Btu/(s·ft²) 6.944 × 10⁻³
50 Btu/(h·ft²) 0.0138889 Btu/(s·ft²) 1.389 × 10⁻²
100 Btu/(h·ft²) 0.0277778 Btu/(s·ft²) 2.778 × 10⁻²
250 Btu/(h·ft²) 0.0694444 Btu/(s·ft²) 6.944 × 10⁻²
500 Btu/(h·ft²) 0.138889 Btu/(s·ft²) 1.389 × 10⁻¹
1000 Btu/(h·ft²) 0.277778 Btu/(s·ft²) 2.778 × 10⁻¹
Btu (IT)/second/square foot to Btu (IT)/hour/square foot: Reciprocal Summary
Btu (IT)/second/square foot to Btu (IT)/hour/square foot Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu/(s·ft²) 3600 Btu/(h·ft²) 3.6 × 10³
5 Btu/(s·ft²) 18000 Btu/(h·ft²) 1.8 × 10⁴
10 Btu/(s·ft²) 36000 Btu/(h·ft²) 3.6 × 10⁴
50 Btu/(s·ft²) 180000 Btu/(h·ft²) 1.8 × 10⁵
100 Btu/(s·ft²) 360000 Btu/(h·ft²) 3.6 × 10⁵
View Complete 15-Row Btu (IT)/second/square foot to Btu (IT)/hour/square foot 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/square foot (Btu/(h·ft²)) and Btu (IT)/second/square foot (Btu/(s·ft²)):

Btu (IT)/hour/square foot References:

  • Direct summer sunshine striking asphalt shingle roof surface 300 Btu/(h·ft²)
  • Residential cast iron steam heating radiator surface heat flux 240 Btu/(h·ft²)

Btu (IT)/second/square foot References:

  • Atmospheric orbital reentry heat shield peak aerodynamic flux 50 Btu/(s·ft²)

Tap any benchmark above to automatically calculate its exact equivalent in Btu (IT)/second/square foot.

ISQ Dimension: [M T⁻³] Coherent SI Unit: watt per square meter (W/m²) Thermodynamics & Heat Transfer

How to Convert Btu (IT)/hour/square foot to Btu (IT)/second/square foot

Converting Btu (IT)/hour/square foot (Btu/(h·ft²)) to Btu (IT)/second/square foot (Btu/(s·ft²)) is a core calculation in Heat Flux Density, which measures the rate of thermal energy transfer radiating or conducting through a unit area per second. 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/square foot equals 0.000277778 Btu (IT)/second/square foot, while 1 Btu/(s·ft²) equals 3600 Btu/(h·ft²).

Direct Factor1 Btu/(h·ft²) = 0.000277778 Btu/(s·ft²)
Inverse Ratio1 Btu/(s·ft²) = 3600 Btu/(h·ft²)
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 (W/m²)) 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) = 3.154591 watt per square meter (W/m²)
2. Target SI Bridge (ktarget):1 Btu/(s·ft²) = 11356.526682 watt per square meter (W/m²)
Step-by-step substitution for Btu (IT)/hour/square foot → Btu (IT)/second/square foot:V(Btu/(s·ft²)) = V(Btu/(h·ft²)) × ( 3.154591 / 11356.526682 ) = V(Btu/(h·ft²)) × 0.000277778
Mathematical FormulaValue in Btu (IT)/second/square foot = Value in Btu (IT)/hour/square foot × 0.00027777778Direct computational formula applied for standard conversion.
Worked Example

For an engineering input of 36 Btu/(h·ft²), applying the conversion factor yields exactly 0.01 Btu/(s·ft²). At larger operational scale, 100 Btu (IT)/hour/square foot corresponds to 0.0277778 Btu/(s·ft²).

Inverse check: 1 Btu/(s·ft²) = 3600 Btu/(h·ft²).

Understanding Btu (IT)/hour/square foot and Btu (IT)/second/square foot

Btu (IT)/hour/square foot

Btu/(h·ft²)
Imperial / US

A Btu (IT)/hour/square foot (Btu/(h·ft²)) is an imperial and US customary unit for heat flux density.

Applications & Practical Context

In practical heat flux density terms, a direct summer sunshine striking asphalt shingle roof surface equals 300 Btu/(h·ft²), a residential cast iron steam heating radiator surface heat flux equals 240 Btu/(h·ft²).

Physical Setup

A physical magnitude of 1 Btu/(h·ft²) corresponds to 3.154591 W/m² in standard SI measurement.

Conversion to SI Unit: watt per square meter (W/m²)
1 Btu/(h·ft²) = 3.154591 W/m²

Btu (IT)/second/square foot

Btu/(s·ft²)
Imperial / US

A Btu (IT)/second/square foot (Btu/(s·ft²)) is an imperial and US customary unit for heat flux density.

Applications & Practical Context

In practical heat flux density terms, a atmospheric orbital reentry heat shield peak aerodynamic flux equals 50 Btu/(s·ft²).

Physical Setup

A physical magnitude of 1 Btu/(s·ft²) corresponds to 11356.526682 W/m² in standard SI measurement.

Conversion to SI Unit: watt per square meter (W/m²)
1 Btu/(s·ft²) = 11356.526682 W/m²

Domain Metrology & Engineering Applications

Governing Law & Equation

Thermal Transmission Flux (q = Q̇ / A)

Measurement Instrumentation

Rigorously quantified in laboratory and field settings using Schmidt-Boelter heat flux gauges, differential thermopile foil transducers, and calibrated Gardon radiant gauges.

Primary Industry Sectors

Applied across rocket nozzle combustion chamber analysis, fire resistance testing (ASTM E119), furnace wall heat loss auditing, and hypersonic aerothermal design under international metrology standard ISO 80000-5:2019, ASME PTC 19.3.

Institutional Metrology & Standard Authority:

Formulas, conversion coefficients, and base definitions on this page strictly adhere to the ISO 80000-5:2019, ASME PTC 19.3 and the BIPM SI Brochure (9th Edition). Governed by Thermal Transmission Flux (q = Q̇ / A) under ISO 80000 dimensional vector [M T⁻³].

Multi-Variable Engineering Bridge Thermal Radiation & Power Dissipation

Heat Flux Density to Total Thermal Power Bridge (Watts • Kilowatts • Megawatts • BTU/h • Horsepower)

Calculate total continuous heat dissipation power P = q" × A across surface barriers and exchangers, bridging heat flux density [M T⁻³] with thermal power [M L² T⁻³].

P = q" × A
Vector: [W/m²] × [m²] → [W]
Live Calculated Bridge Equivalent:
1 Btu/(h·ft²) at Industrial Hydronic Radiator Panel (8 m²) = 25.2367 W
Equals 0.02524 kW • 2.523673 × 10⁻⁵ MW • 0.03384 hp
SI Power
25.2367
W
Watts
Grid / Utility
0.02524
kW
Kilowatts
Power Plant
2.523673 × 10⁻⁵
MW
Megawatts
Mechanical Rating
0.03384
hp
Horsepower (Mechanical)
Metric Horsepower
0.03431
PS
Metric Horsepower (PS)
HVAC Thermal Rating
86.11
BTU/h
BTU per Hour
  1. 1. Normalize Input to SI Base Unit (W/m²):
    q" = 1 Btu/(h·ft²) × 3.15459075 = 3.15459075 W/m²
  2. 2. Apply Engineering Parameter (A):
    Selected condition: Industrial Hydronic Radiator Panel (8 m²) at A = 8 m²
  3. 3. Execute Governing Physical Law in SI Units:
    P = q" × A = (3.15459075 W/m²) × (8 m²) = 25.236726 W
  4. 4. Convert to Standard Engineering Units:
    • W: 25.236726 × 1 = 25.2367 W (Watts) • kW: 25.236726 × 0.001 = 0.02524 kW (Kilowatts) • MW: 25.236726 × 1 × 10⁻⁶ = 2.523673 × 10⁻⁵ MW (Megawatts) • hp: 25.236726 × 0.001341 = 0.03384 hp (Horsepower (Mechanical)) • PS: 25.236726 × 0.00136 = 0.03431 PS (Metric Horsepower (PS)) • BTU/h: 25.236726 × 3.4121 = 86.11 BTU/h (BTU per Hour)
Explore Full Power Converter →
Engineering Substance / Operating Standard Parameter Value (m²) Reference State / Condition Typical Industrial & Engineering Application
Residential Window Glazing (4 m²) 4 4.0 m² Double-pane exterior window glass aperture
Industrial Hydronic Radiator Panel (8 m²) 8 8.0 m² Convective space heating radiator surface
Shell & Tube Heat Exchanger (50 m²) 50 50.0 m² Industrial process fluid cooling bundle
Power Boiler Waterwall (200 m²) 200 200.0 m² Thermal power plant steam generator wall
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Frequently Asked Questions

There are exactly 0.00027777778 btus (it)/second/square foot (Btu/(s·ft²)) in 1 btu (it)/hour/square foot (Btu/(h·ft²)). To calculate larger amounts manually, simply multiply your total number of btus (it)/hour/square foot by the conversion multiplier of 0.00027777778.

The mathematical formula to convert btus (it)/hour/square foot to btus (it)/second/square foot is: [value] * 0.00027777778 = btus (it)/second/square foot. 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 (it)/second/square foot back to btus (it)/hour/square foot, you must divide your starting value by 0.00027777778. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (it)/second/square foot input field.

1 Btu (IT)/second/square foot is larger than 1 Btu (IT)/hour/square foot. Specifically, 1 Btu (IT)/hour/square foot equals 0.00027777778 btus (it)/second/square foot, meaning 1 Btu (IT)/second/square foot is 3600 times larger than 1 Btu (IT)/hour/square foot (a difference of 3.56 orders of magnitude). Expressing measurements in btus (it)/hour/square foot requires a larger numerical value to represent the equivalent physical magnitude.

Under standard international measurement guidelines, 1 Btu (IT)/hour/square foot converts to 0.00027777778 btus (it)/second/square foot. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.