Convert Horsepower-Hours to Ergs

Convert Horsepower-Hours (hp·h) to Ergs (erg) instantly and accurately.

Conversion Formula

erg = hp·h × 26845195380000

About Horsepower-Hours

A horsepower-hour (hp·h) is the energy from one mechanical horsepower (745.6999 W) for one hour - exactly 2,684,519.54 J ≈ 2.685 MJ. James Watt coined the horsepower to compare his steam engines with mine horses; billing in hp·h preceded the kilowatt-hour tariff. The metric horsepower (PS = 75 kgf·m/s = 735.499 W) gives a slightly smaller metric-hp·h = 2,647,795 J, used in European and Japanese engine datasheets. Today the hp·h appears in marine engineering logs, mining energy accounting, and vintage industrial equipment. 1 hp·h = 2.6845 MJ = 0.74570 kWh = 641.19 kcal.

About Ergs

An erg is the CGS unit of energy - the work done by one dyne through one centimetre - exactly 10⁻⁷ J. Despite SI adoption, the erg persists in astrophysics: the Sun's luminosity is 3.828 × 10³³ erg/s; gamma-ray burst isotropic energies are quoted in units of 10⁵¹ erg ('one foe'). Surface tension of water is 72.8 dyn/cm; the work to create 1 cm² of new water-air interface is 72.8 erg. Earthquake seismic moment M₀ is in dyn·cm = erg; the 2004 Boxing Day earthquake had M₀ ≈ 10²³ J = 10³⁰ erg. 1 erg = 10⁻⁷ J = 624.15 eV.

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