It's about 20,000,000 times as long as The First movie.
In other words, 18 months is 22,400,000 times the length of The First movie, and the length of The First movie is 0.00000004460 times that amount.(1888) (Roundhay Garden Scene, National Museum of Photography, Film, and Television restored copy)
Filmed in 1888 by Louis Aimé Augustin Le Prince, Roundhay Garden Scene is the oldest surviving motion picture with a total running time of 0.0000008030 months.
It's about 6,000,000 times as long as a Pit Stop.
It's about 4,000,000 times as long as The First airplane flight (Wright Flyer, 1903).
In other words, 18 months is 3,900,000 times the length of The First airplane flight (Wright Flyer, 1903), and the length of The First airplane flight (Wright Flyer, 1903) is 0.000000260 times that amount.(Wright Flyer) (1903)
The first successful airplane flight was made by Orville Wright on December 17th, 1903 and lasted 0.00000460 months, covering a horizontal distance of 37 m (121.39 ft). The stopwatch used by Orville and his brother Wilbur to time this flight is on display at the Smithsonian National Air and Space Museum in Washington, D.C.
It's about 900,000 times as long as The San Francisco earthquake of 1906.
In other words, 18 months is 901,000 times the length of The San Francisco earthquake of 1906, and the length of The San Francisco earthquake of 1906 is 0.000001110 times that amount.(1906) (Mussel Rock Fault, California) (sensible duration)
The San Francisco earthquake of 1906 caused perceptible shaking of the ground for about 0.0000200 months. The most devastating natural disaster in California's history, the quake was felt as far away and southern Oregon and western Nevada, and resulted in about 3,000 deaths, the displacement of 55% - 70% of the city's population, and the shifting of some spots of ground by up to 6 m (20 ft).
It's about 65,000 times as long as The First spacewalk.
In other words, the length of The First spacewalk is 0.0000150 times 18 months.(1965) (Alexi Lenovo, a.k.a. Алексе́й Архи́пович Лео́нов)
On March 18th, 1965, during the Voskhod 2 Soviet space mission, cosmonaut Alexey Arkhipovich Leonov conducted the first human spacewalk, which lasted 0.00027 months. The total mission length was 0.036 months.
It's about 50,000 times as long as Louis-Antoine's reign.
In other words, the length of Louis-Antoine's reign is 0.0000200 times 18 months.(a.k.a. Louis-Antoine d'Artois, petit-fils de France, fils de France, duc d'Angoulême, a.k.a. Count of Marnes) (1830)
Following his father, Charles X's, abdication on the eve of the 1830 French Revolution, Louis-Antoine d'Artois was technically king for a period of approximately 0.0005 months on August 2nd, 1830. Louis-Antoine's only official act as king was to abdicate the throne to his nephew, the Henri, the Duke of Bordeaux.
It's about 15,000 times as long as a Basketball game.
In other words, 18 months is 16,400 times the length of a Basketball game, and the length of a Basketball game is 0.0000610 times that amount.(NBA regulation; playing time only)
Per National Basketball Association rules , a basketball game (without an overtime) consists of four periods of 0.000274 months each, for a total of 0.0011 months of playing time. The first basketball game, played in a Springfield Massachusetts YMCA, was played in 0.000685 months and ended with a score of 1-0.