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Btus (th)/second/sq. foot to Btus (th)/second/sq. inch Converter (Btu/(s·ft²) to Btu/(s·in²))

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Live Conversion • ISO 80000-5:2019 Certified
1 BTU (th)/second/sq. foot = 0.0069444441 BTU (th)/second/sq. inch
1 Btu/(s·ft²) = 0.00694444 Btu/(s·in²) • 1 Btu/(s·in²) = 144.000007 Btu/(s·ft²)
BTU (th)/second/sq. foot to BTU (th)/second/sq. inch: One BTU (th)/second/sq. foot is equal to 0.0069444441 Btus (th)/second/sq. inch.
Certified Authority Value
0.00694444
Btu/(s·in²)
Exact: 1 Btu/(s·in²) ≡ 144.0000070491 Btu/(s·ft²)
Btu/(s·ft²)
Btu/(s·ft²)
Swap to BTU (th)/second/sq. inch to BTU (th)/second/sq. foot
Swap to BTU (th)/second/sq. inch to BTU (th)/second/sq. foot
Btu/(s·in²)
Btu/(s·in²) 0.0069444441
Quick Values:
Conversion Formula
To convert BTU (th)/second/sq. foot to BTU (th)/second/sq. inch, multiply by 0.0069444441
Btu/(s·ft²) × 0.0069444441 = Btu/(s·in²)

Calculation: 1 Btu/(s·ft²) × 0.0069444441 = 0.0069444441 Btu/(s·in²)

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

Quick-lookup reference table showing calculated equivalents for standard increments between BTU (th)/second/sq. foot (Btu/(s·ft²)) and BTU (th)/second/sq. inch (Btu/(s·in²)).

Tap any row to calculate
BTU (th)/second/sq. foot to BTU (th)/second/sq. inch: Primary Direct Table (15 Steps)
BTU (th)/second/sq. foot to BTU (th)/second/sq. inch Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 Btu/(s·ft²) 6.944444 × 10⁻⁶ Btu/(s·in²) 6.944 × 10⁻⁶
0.01 Btu/(s·ft²) 6.944444 × 10⁻⁵ Btu/(s·in²) 6.944 × 10⁻⁵
0.1 Btu/(s·ft²) 0.000694444 Btu/(s·in²) 6.944 × 10⁻⁴
0.5 Btu/(s·ft²) 0.00347222 Btu/(s·in²) 3.472 × 10⁻³
1 Btu/(s·ft²) 0.00694444 Btu/(s·in²) 6.944 × 10⁻³
2 Btu/(s·ft²) 0.0138889 Btu/(s·in²) 1.389 × 10⁻²
5 Btu/(s·ft²) 0.0347222 Btu/(s·in²) 3.472 × 10⁻²
10 Btu/(s·ft²) 0.0694444 Btu/(s·in²) 6.944 × 10⁻²
20 Btu/(s·ft²) 0.138889 Btu/(s·in²) 1.389 × 10⁻¹
25 Btu/(s·ft²) 0.173611 Btu/(s·in²) 1.736 × 10⁻¹
50 Btu/(s·ft²) 0.347222 Btu/(s·in²) 3.472 × 10⁻¹
100 Btu/(s·ft²) 0.694444 Btu/(s·in²) 6.944 × 10⁻¹
250 Btu/(s·ft²) 1.736111 Btu/(s·in²) 1.736 × 10⁰
500 Btu/(s·ft²) 3.472222 Btu/(s·in²) 3.472 × 10⁰
1000 Btu/(s·ft²) 6.944444 Btu/(s·in²) 6.944 × 10⁰
BTU (th)/second/sq. inch to BTU (th)/second/sq. foot: Reciprocal Summary
BTU (th)/second/sq. inch to BTU (th)/second/sq. foot Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 Btu/(s·in²) 144.000007 Btu/(s·ft²) 1.44 × 10²
5 Btu/(s·in²) 720.000035 Btu/(s·ft²) 7.2 × 10²
10 Btu/(s·in²) 1440.00007 Btu/(s·ft²) 1.44 × 10³
50 Btu/(s·in²) 7200.000352 Btu/(s·ft²) 7.2 × 10³
100 Btu/(s·in²) 14400.000705 Btu/(s·ft²) 1.44 × 10⁴
View Complete 15-Row BTU (th)/second/sq. inch 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)/second/sq. inch (Btu/(s·in²)):

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)/second/sq. inch References:

  • Solar constant extraterrestrial solar irradiance at top of atmosphere 0.000833 Btu/(s·in²)
  • Clear sky direct midday summer sunlight striking sea level ground 0.000612 Btu/(s·in²)
  • Human body resting thermal metabolic heat radiation to room 3.1E-5 Btu/(s·in²)
  • Overcast winter day diffuse solar irradiance at sea level 6.1E-5 Btu/(s·in²)

Tap any benchmark above to automatically calculate its exact equivalent in BTU (th)/second/sq. inch.

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)/second/sq. inch

Converting BTU (th)/second/sq. foot (Btu/(s·ft²)) to BTU (th)/second/sq. inch (Btu/(s·in²)) 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 0.00694444 BTU (th)/second/sq. inch, while 1 Btu/(s·in²) equals 144.000007 Btu/(s·ft²).

Direct Factor1 Btu/(s·ft²) = 0.00694444 Btu/(s·in²)
Inverse Ratio1 Btu/(s·in²) = 144.000007 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/(s·in²) = 1634246 watt per square meter (W/m²)
Step-by-step substitution for BTU (th)/second/sq. foot → BTU (th)/second/sq. inch:V(Btu/(s·in²)) = V(Btu/(s·ft²)) × ( 11348.93 / 1634246 ) = V(Btu/(s·ft²)) × 0.00694444
Mathematical FormulaValue in BTU (th)/second/sq. inch = Value in BTU (th)/second/sq. foot × 0.0069444441Direct computational formula applied for standard conversion.
Worked Example

For an engineering input of 75 Btu/(s·ft²), applying the conversion factor yields exactly 0.520833 Btu/(s·in²). At larger operational scale, 100 BTU (th)/second/sq. foot corresponds to 0.694444 Btu/(s·in²).

Inverse check: 1 Btu/(s·in²) = 144.000007 Btu/(s·ft²).

Understanding BTU (th)/second/sq. foot and BTU (th)/second/sq. inch

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)/second/sq. inch

Btu/(s·in²)
Imperial / US

A BTU (th)/second/sq. inch (Btu/(s·in²)) 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 0.000833 Btu/(s·in²), a clear sky direct midday summer sunlight striking sea level ground equals 0.000612 Btu/(s·in²), a human body resting thermal metabolic heat radiation to room equals 3.1 × 10⁻⁵ Btu/(s·in²).

Physical Setup

A physical magnitude of 1 Btu/(s·in²) corresponds to 1634246 W/m² in standard SI measurement.

Conversion to SI Unit: watt per square meter (W/m²)
1 Btu/(s·in²) = 1634246 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 0.0069444441 btus (th)/second/sq. inch (Btu/(s·in²)) 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 0.0069444441.

The mathematical formula to convert btus (th)/second/sq. foot to btus (th)/second/sq. inch is: [value] * 0.0069444441 = btus (th)/second/sq. inch. 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. inch back to btus (th)/second/sq. foot, you must divide your starting value by 0.0069444441. Our bidirectional tool automatically computes this inverse equation the moment you type into the btu (th)/second/sq. inch input field.

1 BTU (th)/second/sq. inch is larger than 1 BTU (th)/second/sq. foot. Specifically, 1 BTU (th)/second/sq. foot equals 0.0069444441 btus (th)/second/sq. inch, meaning 1 BTU (th)/second/sq. inch is 144 times larger than 1 BTU (th)/second/sq. foot (a difference of 2.16 orders of magnitude). Expressing measurements in btus (th)/second/sq. foot requires a larger numerical value to represent the equivalent physical magnitude.

Under standard international measurement guidelines, 1 BTU (th)/second/sq. foot converts to 0.0069444441 btus (th)/second/sq. inch. Precise numerical conversion factors ensure consistency across laboratory, engineering, and field data.