23 Unusually Odd Measurement Units People Actually Use

1 Potrzebie equals 2.263348517438173216473 mm or, the precise mathematical thickness of MAD Magazine #26. It is based on a running gag in the early days of MAD magazine. The Potrzebie was invented in 1957 by 19-year-old future computer scientist and Stanford Professor Emeritus Donald Knuth. It is still available for conversion in Google calculator.

The Crab is defined as the intensity of X-rays emitted from the Crab Nebula at given photon energy up to 30 kiloelectronvolts. The Crab Nebula is often used for calibration of X-ray telescopes.

Every second we talk on a phone, erlangs are ticking in the counter; the unit is used to measure telecommunications traffic. One erlang is equal to one hour of continuous traffic per voice path. Erlang measurements are vital in helping engineers understand telecommunications patterns and create networks that don’t crash under the sheer volume of calls.

Sheppey is a measure of distance that equals to about 7⁄8th of a mile (1.4 km), defined as the closest distance at which sheep remain picturesque. The Sheppey is the creation of Douglas Adams and John Lloyd, included in The Meaning of Liff, their dictionary of putative meanings for words that are actually just place names.

The Thaum is a measuring unit used in the Terry Pratchett series of Discworld novels to quantify magic. It equals the amount of mystical energy required to conjure up one small white pigeon, or three normal-sized billiard balls.

The Economist's Big Mac Index compares the purchasing power parity of countries in terms of the cost of a Big Mac hamburger. This was felt to be a good measure of the prices of a basket of commodities in the local economy including labor, rent, meat, bread, cardboard, advertising, lettuce, etc. The purchasing power of a country is measured in how many Big Macs could be bought in that country with $50 USD.

A Micromort is a unit of risk measuring a one-in-a-million probability of death. Micromorts can be used to measure the riskiness of various day-to-day activities. For example, smoking 1.4 cigarettes increases one's death risk by one micromort, as does traveling 230 miles by car.

The Popsicle Index is a quality of life measurement based on the percentage of people in a community who believe that a child in their community can safely leave their home, walk to the nearest possible location to buy a popsicle, and walk back home.

According to Encyclopedia Britannica Almanac 2009, a pony is 0.75 ounces.

A Morgen (morning in Dutch) was approximately the amount of land tillable by one man behind an ox in the morning hours of a day. This was an official unit of measurement in South Africa until the 1970s and was defined in November 2007 by the South African Law Society as having a conversion factor of 1 Morgen = 0.856 532 hectares.