It's about one-and-one-tenth times as tall as a Giraffe
It's about three-fourths as long as a London bus
In other words, 20 feet is 0.727 times the length of a London bus, and the length of a London bus is 1.38 times that amount.(Routemaster Double-Decker, RM standard specification)
The Routemaster Double-Decker buses, well-known as icons of London, measure 27.50 feet in length. The buses were said to be well-designed for travel in the London traffic, as they offered an open door for riders to board and exit even while the bus was moving at low speeds, and a full-time conductor to collect fares.
It's about one-and-a-half times as long as a Beetle (Volkswagen)
In other words, 20 feet is 1.494 times the length of a Beetle (Volkswagen), and the length of a Beetle (Volkswagen) is 0.6693 times that amount.(1964 model) (a.k.a. Volkswagen 1200, a.k.a. Käfer)
A 1964 Volkswagen Beetle measures 13.380 feet. As the longest continuously-produced automobile design — in production for 75 years between 1938 and 2003 — the Beetle was voted the most fourth-most influential car of the twentieth century by the Global Automotive Elections Foundation.
It's about half as tall as a Telephone Pole
In other words, 20 feet is 0.55 times the height of a Telephone Pole, and the height of a Telephone Pole is 1.8 times that amount.(a.k.a. Utility Pole, a.k.a Power Pole, a.k.a. Telegraph Pole, a.k.a. Telegraph Post, a.k.a. Hydro Pole) (exposed height; per Florida Public Service Commission average)
A standard telephone pole is 36 feet tall. Despite alternatives, most telephone poles in the US are made of wood — most commonly pine — and have a lifespan of 25 to 50 years, depending on climate and preservatives applied.
It's about half as tall as a Brachiosaurus
In other words, 20 feet is 0.47 times the height of a Brachiosaurus, and the height of a Brachiosaurus is 2.1 times that amount.(based on comparable bone measurements, height to head)
Dinosaurs in the genus Brachiosaurus had an estimated height (at the head with neck fully extended) of up to 43 feet. A resin cast of the first Brachiosaurus specimen, owned by the Field Museum in Chicago, is currently on display at the O'Hare International Airport.
It's about two-fifths as long as a Semitrailer
In other words, 20 feet is 0.4167 times the length of a Semitrailer, and the length of a Semitrailer is 2.4 times that amount.(a.k.a. semi-trailer truck, a.k.a. semi, a.k.a. tractor-trailer, a.k.a. truck and trailer, a.k.a. eighteen-wheeler, a.k.a. big rig, a.k.a. Mack truck, a.k.a. transport, a.k.a. lorry, a.k.a. artic; for box truck; United States Federal length limits)
According to the United States Department of Transportation (DOT), the maximum allowable length of a semitrailer pulled by a road tractor truck is 48 feet (unless superseded by state law). These regulations also allow the vehicles to tow up to 36,000 kg in gross weight.
It's about two-fifths as tall as The Hollywood Sign
In other words, 20 feet is 0.41 times the height of The Hollywood Sign, and the height of The Hollywood Sign is 2.4 times that amount.(a.k.a. Hollywoodland Sign) (Mount Lee, Hollywood Hills, Santa Monica Mountains, California)
Each of the white letters in the Hollywood Sign measures 49 feet tall. Built as an advertisement in 1923, the sign was intended to stand for only eighteen months.