Converts power between W, kW, mechanical hp, metric hp, and BTU/h using exact NIST SP 811 watt-equivalents.
Published for review. The Founder is checking every card himself; anything he strikes comes down the same hour.
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Inputs
value (number, from_unit, required) : The power to convert
from_unit (string, required) one of: W, kW, hp_mech, hp_metric, btu_h : Unit of the input value
to_unit (string, required) one of: W, kW, hp_mech, hp_metric, btu_h : Unit to convert into
Outputs
result (to_unit): The converted power
Steps
Look up the exact watt-equivalent of from_unit and of to_unit.
Convert the input to watts: watts = value * w_per(from_unit).
Convert watts to the target unit: result = watts / w_per(to_unit).
Round result to 6 significant figures.
Constants
W = 1 W (source: Guide for the Use of the International System of Units (SI))
kW = 1000 W (source: Guide for the Use of the International System of Units (SI))
hp_mech = 745.6998715822702 W (source: Guide for the Use of the International System of Units (SI))
hp_metric = 735.49875 W (source: Guide for the Use of the International System of Units (SI))
btu_h = 0.2930710701722222 W (source: Guide for the Use of the International System of Units (SI))
Sources
Guide for the Use of the International System of Units (SI) (National Institute of Standards and Technology, 2026-09-30T19:29:48Z) - Mechanical (imperial) horsepower = 550 ft*lbf/s built from the exact foot and pound-force; metric horsepower = 75 kgf*m/s = 75 * 9.80665 W exactly; BTU/h uses the exact BTU (IT) over one hour.