- Doc: "1.21 jigowatts!!!"
- Marty: "What the hell is a jigowatt?"
- — Doc and Marty discussing the video
A jigowatt was a large amount of electricity, equivalent to 1 billion watts. The average light bulb was only 100 watts. It took either a nuclear reaction or a bolt of lightning to generate up to 1.21 jigowatts, what Doc Brown needed to power the electrical DeLorean time machine via the flux capacitor.
Behind the scenes
The "jigowatt" is really the gigawatt that was misspelt by the producers Bob Gale and Robert Zemeckis while filming Back to the Future, and became the standard spelling for the movie. It could then be interpreted in-universe that Doc pronounced gigawatt as jigowatt.
"Jigowatt" is also a well-known Back to the Future themed Creative Design Agency based in Peterborough, UK.