Convert Btu (IT) per Hour per Square Foot to Foot Pounds per Minute per Square Foot
Btu (IT) per Hour per Square Foot (Btu/(h·ft²)) to Foot Pound per Minute per Square Foot (ft·lb/(min·ft²)) heat flux density conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 Btu/(h·ft²) = 12.971217 ft·lb/(min·ft²)
1 Btu (IT) per Hour per Square Foot = 12.971217 Foot Pounds per Minute per Square Foot
1 Foot Pound per Minute per Square Foot = 0.077093768 Btu (IT) per Hour per Square Foot
1 Btu/(h·ft²) in every supported unit
Conversion chart: Btu (IT) per Hour per Square Foot to Foot Pounds per Minute per Square Foot
Conversion table
| Btu (IT) per Hour per Square Foot (Btu/(h·ft²)) | Foot Pound per Minute per Square Foot (ft·lb/(min·ft²)) |
|---|---|
| 0.01 Btu/(h·ft²) | 0.12971217 ft·lb/(min·ft²) |
| 0.1 Btu/(h·ft²) | 1.2971217 ft·lb/(min·ft²) |
| 1 Btu/(h·ft²) | 12.971217 ft·lb/(min·ft²) |
| 2 Btu/(h·ft²) | 25.942434 ft·lb/(min·ft²) |
| 3 Btu/(h·ft²) | 38.913651 ft·lb/(min·ft²) |
| 5 Btu/(h·ft²) | 64.856086 ft·lb/(min·ft²) |
| 10 Btu/(h·ft²) | 129.71217 ft·lb/(min·ft²) |
| 20 Btu/(h·ft²) | 259.42434 ft·lb/(min·ft²) |
| 50 Btu/(h·ft²) | 648.56086 ft·lb/(min·ft²) |
| 100 Btu/(h·ft²) | 1297.1217 ft·lb/(min·ft²) |
| 1000 Btu/(h·ft²) | 12971.217 ft·lb/(min·ft²) |
Btu (IT) per Hour per Square Foot (Btu/(h·ft²))
Definition: The standard US customary heat flux unit — British thermal units passing through one square foot of surface, per hour.
History: Built from the Btu, hour, and square foot, all standard US construction and HVAC measurements, giving American building engineers a heat-flow-rate unit matching everyday design calculations.
Current use: The standard unit for building heat-gain and heat-loss calculations in US HVAC engineering, printed throughout ASHRAE design guides and load-calculation software.
Foot Pound per Minute per Square Foot (ft·lb/(min·ft²))
Definition: A mechanical-work-based US customary heat flux unit — foot-pounds of work-equivalent energy passing through one square foot per minute.
History: Rooted in the US customary mechanical work tradition (foot-pound, the same unit used for torque and mechanical energy), applied here to a heat-transfer-rate context.
Current use: Rare in modern practice, occasionally found in older US mechanical engineering references that expressed heat flow in mechanical work units rather than thermal Btu units.
Supported Units
| Unit | Symbol | In W/m² |
|---|---|---|
| Watt per Square Meter | W/m² | 1 W/m² |
| Kilowatt per Square Meter | kW/m² | 1000 W/m² |
| Watt per Square Centimeter | W/cm² | 10000 W/m² |
| Watt per Square Inch | W/in² | 1550.0031 W/m² |
| Kilocalorie (IT) per Hour per Square Meter | kcal/(h·m²) | 1.163 W/m² |
| Calorie (IT) per Second per Square Centimeter | cal/(s·cm²) | 41868 W/m² |
| Btu (IT) per Hour per Square Foot | Btu/(h·ft²) | 3.1546 W/m² |
| Btu (IT) per Second per Square Foot | Btu/(s·ft²) | 11356.53 W/m² |
| Horsepower per Square Foot | hp/ft² | 8026.65 W/m² |
| Foot Pound per Minute per Square Foot | ft·lb/(min·ft²) | 0.2432 W/m² |
About These Parameters
- Value
- The heat flux density value you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in — a solar spec sheet's W/m², or a US HVAC load calculation's Btu/(h·ft²).
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Heat Flux Density Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to watts per square meter. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Btu (IT) per Hour per Square Foot → Foot Pound per Minute per Square Foot: multiply by 12.971217. For example, 1 Btu/(h·ft²) × 12.971217 = 12.971217 ft·lb/(min·ft²).
Solar Irradiance
"1,000 W/m²" is the standard reference solar irradiance used to rate solar panels under laboratory "Standard Test Conditions" — roughly what a clear, midday sun delivers to a surface facing directly toward it. Real-world irradiance varies constantly with time of day, cloud cover, and season, which is why a panel's rated wattage (measured at that fixed 1,000 W/m² reference) rarely matches its actual output at any given moment.
Heat Flux Density vs. Heat Density
This page's units are all RATES (power per area, e.g. watts per square meter) — how fast energy is moving right now. The site's separate Heat Density Converter covers the cumulative TOTAL (energy per area, e.g. joules per square meter) — how much energy has landed altogether over some period. Multiplying a heat flux density by a duration of time gives you a heat density, the same relationship speed has to distance.
Example
A heat flux density of 1 Btu/(h·ft²) equals 12.971217 ft·lb/(min·ft²). For scale, peak midday solar irradiance is around 1,000 W/m² (about 317 Btu/(h·ft²)), while a typical well-insulated wall might lose heat at only a few W/m² on a cold day.
Frequently Asked Questions
How many Foot Pounds per Minute per Square Foot are in 1 Btu (IT) per Hour per Square Foot?
1 Btu (IT) per Hour per Square Foot (Btu/(h·ft²)) equals exactly 12.971217 Foot Pounds per Minute per Square Foot (ft·lb/(min·ft²)).
Why does this page have so many units compared to other converters?
Heat flux density is used across an unusually wide range of fields — solar engineering, HVAC, laser physics, industrial heating, and classical thermodynamics — each of which historically settled on its own preferred combination of energy, time, and area units, so this page collects the most commonly seen ones from each.
What's a normal heat flux density value for solar panels?
Solar panels are rated at a standard 1,000 W/m² reference irradiance, but real-world sunlight typically ranges from near 0 (night, heavy cloud) up to around 1,000-1,100 W/m² at clear-sky, high-sun conditions, varying with latitude, season, and time of day.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying power, energy, and area units — results are limited only by floating-point display precision, not by rounded conversion constants.