Skip to main content

Furlong Firkin Fortnight System

From Wikipedia’s references to humorous measures

The Furlong/Firkin/Fortnight (FFF) system is a humorous system of units based on outdated and impractical measurements. The length unit of the system is the furlong, the mass unit is the mass of a firkin of water, and the time unit is the fortnight. Like the SI or metre-kilogram-second system, there are derived units for velocity etc.

While the FFF system is not used in practice, it has been used as an example in discussions of the relative merits of different systems of units. Some of the FFF units, notably the microfortnight, have been used jokingly in computer science. Besides having the meaning “any obscure unit,” furlongs per fortnight have also served frequently in classroom examples of unit conversion and dimensional analysis.

The speed of light may be expressed as being roughly 1.8 terafurlongs per fortnight.

Base units and definitions

Unit Abbreviation Dimension SI unit Imperial unit
furlong fur length 201.168 meter 220 yards
firkin fir mass 40.8233133 kg 90 lb
fortnight ftn time 1,209,600 seconds 14 days

Notable multiples and derived units

One microfortnight is equal to 1.2096 seconds.1 This has become a joke in computer science because in the VMS operating system, the TIMEPROMPTWAIT variable, which holds the time the system will wait for an operator to set the correct date and time at boot if it realizes that the current value is bogus, is set in microfortnights. This is because the computer uses a loop instead of the internal clock which has not been activated yet to run the timer. Millifortnights (about 20 minutes) and nanofortnights (1.2096 milliseconds) have also been used occasionally in computer science, usually in an attempt to be deliberately over-complex and obscure.

One furlong per fortnight, a speed which would be barely noticeable to the naked eye, converts to: 1.663 x 10-4 meter per second, roughly one centimeter per minute (to within 1 part in 400). Indeed, if the inch were defined as 2.5454… cm rather than 2.54 cm exactly, it would be 1 cm/min. 5.987x 10-4 km/h, roughly three eighths of an inch per minute, or 3.720 x 10-4 mph. The expression has also been used figuratively to mean at glacial speed (the pace or rate of progress is experienced as excruciatingly slow), as it is a realistic speed of some glaciers, about 14 m/day. Another notable constant based on those units is the speed of light, known as “Strapp’s Constant” (Jock “Strapp” Marshall), which is 1.8026 x 1012 furlongs/fortnight.2

Like the more common furlongs per fortnight, firkins per fortnight have been used with the meaning “any obscure unit.”

Syngress, 2006, ISBN 1-59749-115-2, p. 122.


The current required to generate a force of two furlong·firkin/fortnight2 (~11.22 nN) per furlong between two parallel conductors one furlong apart is ~237 mA. Or, more in keeping with the spirit of the system, one could simply use either the faraday mole of electrons (96.5 kC - per fortnight = 79.7 mA) or the franklin statcoulomb (333 pC, per fortnight = 275 aA) as the unit of charge.

This is of course all OR, but on the other hand I’ve seen an actual “Furlong/Fortnight/Farad/Faraday” system, whose unit of mass would be faraday2fortnight2/(farad·furlong2) which is 336 Eg (3.36×1017 kg) - substitute the franklin instead of the faraday and it is ~4 ng OTOH for temperature the choice is simpler: Fahrenheit. Random832 (contribs) 21:22, 10 July 2008 (UTC)
And I suppose for angular measure we could define a “fortnight of arc” to be 336 degrees. Solid angle can be measured in “fractions of the sphere”, so that one’s OK. We should really document this discussion somewhere, it’s off-topic for the talkpage and original research for the article! tiny plastic Grey Knight ⊖ 09:00, 17 July 2008 (UTC)
For the base unit of quantity, instead of the mole we could use the “few,” equal to 3. So now we have the furlong, firkin, fortnight, farad, arc fortnight, fraction, and the few (and the faraday which is a derived unit). The unit of force should be the force, equal to the firkin furlong / fortnight2. There should be a unit of luminosity (like the candela) and one of heat (like the calorie), and one of area (like the hectare). What else … pressure? Work? Power? There are LOTS of SI units. Preceding unsigned comment added by (talk) 23:49, 15 August 2008 (UTC)
  1. Robert Slade, Dictionary of information security ,

  2. Paul Connally - 1992 - Derived after several discussions with Jock Marshall concerning his endeavors with fabricating parts for the Cassini deep space project.

Real Time Web Analytics