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

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Live Conversion • ISO 80000-5:2019 Certified
1 BTU (th)/second/sq. foot = 3600.00089466 Btu (th)/hour/sq. foot
1 Btu/(s·ft²) = 3600.000895 Btu(th)/(h·ft²) • 1 Btu(th)/(h·ft²) = 0.000277778 Btu/(s·ft²)
BTU (th)/second/sq. foot to Btu (th)/hour/sq. foot: One BTU (th)/second/sq. foot is equal to 3600.00089466 Btus (th)/hour/sq. foot.
Certified Authority Value
3600.00089466
Btu(th)/(h·ft²)
Exact: 1 Btu(th)/(h·ft²) ≡ 0.0002777777087 Btu/(s·ft²)
Btu/(s·ft²)
Btu/(s·ft²)
Swap to Btu (th)/hour/sq. foot to BTU (th)/second/sq. foot
Swap to Btu (th)/hour/sq. foot to BTU (th)/second/sq. foot
Btu(th)/(h·ft²)
Btu(th)/(h·ft²) 3600.00089466
Quick Values:
Conversion Formula
To convert BTU (th)/second/sq. foot to Btu (th)/hour/sq. foot, multiply by 3600.00089466
Btu/(s·ft²) × 3600.00089466 = Btu(th)/(h·ft²)

Calculation: 1 Btu/(s·ft²) × 3600.00089466 = 3600.00089466 Btu(th)/(h·ft²)

Common BTU (th)/second/sq. foot to Btu (th)/hour/sq. foot Calculations

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

Tap any row to calculate
BTU (th)/second/sq. foot to Btu (th)/hour/sq. foot: Primary Direct Table (15 Steps)
BTU (th)/second/sq. foot to Btu (th)/hour/sq. foot Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu/(s·ft²) 3.600001 Btu(th)/(h·ft²) 3.6 × 10⁰
0.01 Btu/(s·ft²) 36.000009 Btu(th)/(h·ft²) 3.6 × 10¹
0.1 Btu/(s·ft²) 360.000089 Btu(th)/(h·ft²) 3.6 × 10²
0.5 Btu/(s·ft²) 1800.000447 Btu(th)/(h·ft²) 1.8 × 10³
1 Btu/(s·ft²) 3600.000895 Btu(th)/(h·ft²) 3.6 × 10³
2 Btu/(s·ft²) 7200.001789 Btu(th)/(h·ft²) 7.2 × 10³
5 Btu/(s·ft²) 18000.004473 Btu(th)/(h·ft²) 1.8 × 10⁴
10 Btu/(s·ft²) 36000.008947 Btu(th)/(h·ft²) 3.6 × 10⁴
20 Btu/(s·ft²) 72000.017893 Btu(th)/(h·ft²) 7.2 × 10⁴
25 Btu/(s·ft²) 90000.022366 Btu(th)/(h·ft²) 9 × 10⁴
50 Btu/(s·ft²) 180000.044733 Btu(th)/(h·ft²) 1.8 × 10⁵
100 Btu/(s·ft²) 360000.089466 Btu(th)/(h·ft²) 3.6 × 10⁵
250 Btu/(s·ft²) 900000.223665 Btu(th)/(h·ft²) 9 × 10⁵
500 Btu/(s·ft²) 1800000.447329 Btu(th)/(h·ft²) 1.8 × 10⁶
1000 Btu/(s·ft²) 3600000.894658 Btu(th)/(h·ft²) 3.6 × 10⁶
Btu (th)/hour/sq. foot to BTU (th)/second/sq. foot: Reciprocal Summary
Btu (th)/hour/sq. foot to BTU (th)/second/sq. foot Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu(th)/(h·ft²) 0.000277778 Btu/(s·ft²) 2.778 × 10⁻⁴
5 Btu(th)/(h·ft²) 0.00138889 Btu/(s·ft²) 1.389 × 10⁻³
10 Btu(th)/(h·ft²) 0.00277778 Btu/(s·ft²) 2.778 × 10⁻³
50 Btu(th)/(h·ft²) 0.0138889 Btu/(s·ft²) 1.389 × 10⁻²
100 Btu(th)/(h·ft²) 0.0277778 Btu/(s·ft²) 2.778 × 10⁻²
View Complete 15-Row Btu (th)/hour/sq. foot to BTU (th)/second/sq. 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 (th)/second/sq. foot (Btu/(s·ft²)) and Btu (th)/hour/sq. foot (Btu(th)/(h·ft²)):

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

  • Solar constant extraterrestrial solar irradiance at top of atmosphere 0.119923 Btu/(s·ft²)
  • Clear sky direct midday summer sunlight striking sea level ground 0.088114 Btu/(s·ft²)
  • Human body resting thermal metabolic heat radiation to room 0.004406 Btu/(s·ft²)
  • Overcast winter day diffuse solar irradiance at sea level 0.008811 Btu/(s·ft²)

Btu (th)/hour/sq. foot References:

  • Solar constant extraterrestrial solar irradiance at top of atmosphere 431.72 Btu(th)/(h·ft²)
  • Clear sky direct midday summer sunlight striking sea level ground 317.21 Btu(th)/(h·ft²)
  • Human body resting thermal metabolic heat radiation to room 15.8605 Btu(th)/(h·ft²)
  • Overcast winter day diffuse solar irradiance at sea level 31.7211 Btu(th)/(h·ft²)

Tap any benchmark above to automatically calculate its exact equivalent in Btu (th)/hour/sq. foot.

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

How to Convert BTU (th)/second/sq. foot to Btu (th)/hour/sq. foot

Converting BTU (th)/second/sq. foot (Btu/(s·ft²)) to Btu (th)/hour/sq. foot (Btu(th)/(h·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 (th)/second/sq. foot equals 3600.000895 Btu (th)/hour/sq. foot, while 1 Btu(th)/(h·ft²) equals 0.000277778 Btu/(s·ft²).

Direct Factor1 Btu/(s·ft²) = 3600.000895 Btu(th)/(h·ft²)
Inverse Ratio1 Btu(th)/(h·ft²) = 0.000277778 Btu/(s·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/(s·ft²) = 11348.93 watt per square meter (W/m²)
2. Target SI Bridge (ktarget):1 Btu(th)/(h·ft²) = 3.15248 watt per square meter (W/m²)
Step-by-step substitution for BTU (th)/second/sq. foot → Btu (th)/hour/sq. foot:V(Btu(th)/(h·ft²)) = V(Btu/(s·ft²)) × ( 11348.93 / 3.15248 ) = V(Btu/(s·ft²)) × 3600.000895
Mathematical FormulaValue in Btu (th)/hour/sq. foot = Value in BTU (th)/second/sq. foot × 3600.00089466Direct computational formula applied for standard conversion.
Worked Example

For an engineering input of 75 Btu/(s·ft²), applying the conversion factor yields exactly 270000.067099 Btu(th)/(h·ft²). At larger operational scale, 5000 BTU (th)/second/sq. foot corresponds to 1.8 × 10⁷ Btu(th)/(h·ft²).

Inverse check: 1 Btu(th)/(h·ft²) = 0.000277778 Btu/(s·ft²).

Understanding BTU (th)/second/sq. foot and Btu (th)/hour/sq. foot

BTU (th)/second/sq. foot

Btu/(s·ft²)
Imperial / US

A BTU (th)/second/sq. 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 solar constant extraterrestrial solar irradiance at top of atmosphere equals 0.119923 Btu/(s·ft²), a clear sky direct midday summer sunlight striking sea level ground equals 0.088114 Btu/(s·ft²), a human body resting thermal metabolic heat radiation to room equals 0.004406 Btu/(s·ft²).

Physical Setup

A physical magnitude of 1 Btu/(s·ft²) corresponds to 11348.93 W/m² in standard SI measurement.

Conversion to SI Unit: watt per square meter (W/m²)
1 Btu/(s·ft²) = 11348.93 W/m²

Btu (th)/hour/sq. foot

Btu(th)/(h·ft²)
Imperial / US

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

Applications & Practical Context

In practical heat flux density terms, a solar constant extraterrestrial solar irradiance at top of atmosphere equals 431.72 Btu(th)/(h·ft²), a clear sky direct midday summer sunlight striking sea level ground equals 317.21 Btu(th)/(h·ft²), a human body resting thermal metabolic heat radiation to room equals 15.8605 Btu(th)/(h·ft²).

Physical Setup

A physical magnitude of 1 Btu(th)/(h·ft²) corresponds to 3.15248 W/m² in standard SI measurement.

Conversion to SI Unit: watt per square meter (W/m²)
1 Btu(th)/(h·ft²) = 3.15248 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/(s·ft²) at Industrial Hydronic Radiator Panel (8 m²) = 90791.44 W
Equals 90.7914 kW • 0.0907914 MW • 121.7533 hp
SI Power
90791.44
W
Watts
Grid / Utility
90.7914
kW
Kilowatts
Power Plant
0.0907914
MW
Megawatts
Mechanical Rating
121.7533
hp
Horsepower (Mechanical)
Metric Horsepower
123.442
PS
Metric Horsepower (PS)
HVAC Thermal Rating
309793.25
BTU/h
BTU per Hour
  1. 1. Normalize Input to SI Base Unit (W/m²):
    q" = 1 Btu/(s·ft²) × 11348.93 = 11348.93 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 = (11348.93 W/m²) × (8 m²) = 90791.44 W
  4. 4. Convert to Standard Engineering Units:
    • W: 90791.44 × 1 = 90791.44 W (Watts) • kW: 90791.44 × 0.001 = 90.7914 kW (Kilowatts) • MW: 90791.44 × 1 × 10⁻⁶ = 0.0907914 MW (Megawatts) • hp: 90791.44 × 0.001341 = 121.7533 hp (Horsepower (Mechanical)) • PS: 90791.44 × 0.00136 = 123.442 PS (Metric Horsepower (PS)) • BTU/h: 90791.44 × 3.4121 = 309793.25 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 3600.00089466 btus (th)/hour/sq. foot (Btu(th)/(h·ft²)) in 1 btu (th)/second/sq. foot (Btu/(s·ft²)). To calculate larger amounts manually, simply multiply your total number of btus (th)/second/sq. foot by the conversion multiplier of 3600.00089466.

The mathematical formula to convert btus (th)/second/sq. foot to btus (th)/hour/sq. foot is: [value] * 3600.00089466 = btus (th)/hour/sq. 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 (th)/hour/sq. foot back to btus (th)/second/sq. foot, you must divide your starting value by 3600.00089466. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (th)/hour/sq. foot input field.

1 BTU (th)/second/sq. foot is larger than 1 Btu (th)/hour/sq. foot. Specifically, 1 BTU (th)/second/sq. foot equals exactly 3600.00089466 btus (th)/hour/sq. foot, making it 3600.0009 times larger (a difference of 3.56 orders of magnitude). Therefore, quantities expressed in btus (th)/hour/sq. foot require a larger numerical value to represent the same physical amount.

Under standard international measurement guidelines, 1 BTU (th)/second/sq. foot converts to 3600.00089466 btus (th)/hour/sq. foot. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.