Joules to Quads (J to quad)

1 joule equals 9.478171203×10⁻¹⁹ quads (rounded).

1 joule = 9.478171203×10⁻¹⁹ quads

How to convert joules to quads

To convert joules to quads, multiply the number of joules by 9.478171203×10⁻¹⁹. The factor is rounded to 10 significant digits. To go the other way, multiply quads by 1.055055853×10¹⁸ (rounded).

quads = joules × 9.478171203×10⁻¹⁹

Example: 10 joules = 9.478171203×10⁻¹⁸ quads.

The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.

About these units

Joule (J)

Metric (SI)Current unit

The SI unit of energy: the work done by a force of one newton over one meter, or one watt for one second.

James Prescott Joule was born in Salford on 24 December 1818, the son of a wealthy brewer, and later ran the family brewery while treating science as a serious hobby. In June 1845 he told a British Association meeting in Cambridge about his best-known experiment: a falling weight turned a paddle wheel inside an insulated barrel of water, and the water warmed up. Mechanical work turned into heat at a fixed rate, which supported energy conservation and undermined the caloric theory of heat.

The unit came later. On 23 August 1882 Carl Wilhelm Siemens proposed at a British Association meeting that a unit of heat equal to 10 million ergs be named the joule, and in 1889 the second International Electrical Congress adopted it alongside the watt. Joule died that same year. In 1948 the CGPM added that the joule should be preferred to the calorie as the unit of heat, and it entered the SI in 1960.

For scale, one joule is about the energy needed to lift an apple of roughly 102 g by one meter. A 56 g tennis ball moving at 6 m/s carries about one joule of kinetic energy.

The joule is the reference unit for energy on this site.

Sources: Wikipedia: Joule; Wikipedia: James Prescott Joule

Quad (quad)

US customaryTraditional unit (still used in some regions)

One quadrillion BTU (about 1.055×10¹⁸ J). Used to quote national and global energy use; US consumption was about 100 quads in 2005.

Energy planners reach for the quad when joules or gallons become unwieldy. One quad is a quadrillion (10 to the 15th power) British thermal units, a figure the US Department of Energy uses for national and world energy budgets. In SI terms it is about 1.055 exajoules, or 1.055 times 10 to the 18th joules.

Which BTU applies changes the last digits. The figure used here, 1.05505585 times 10 to the 18th joules, corresponds to the International Table BTU of roughly 1,055.06 J. The 59 degree Fahrenheit BTU used in American gas pricing would give a value about 0.02 percent smaller, and the Wikipedia article on the quad does not say which BTU it assumes.

For scale, one quad equals about 8 billion US gallons of gasoline or roughly 293 terawatt-hours of electricity. Wikipedia reports world primary energy production of about 638 quads in 2022. In 2005 the US economy used close to 100 quads, so the unit suits country-sized totals rather than anything a household buys.

1 quad = 1.055055853×10¹⁸ joules (approximately).

Sources: Wikipedia: Quad (unit); EIA: British thermal units (Btu); Wikipedia: British thermal unit

Related conversions

See all energy units.