How long is 21 inches?

The traditional and smallest standard size for a ukulele measures exactly 21 inches in total length.

Since World War I, the international standard diameter for heavy submarine torpedoes (and their launch tubes) has been exactly 21 inches (533 mm).

Designed specifically for young beginners (typically ages 4 to 6), a standard lightweight junior tennis racket is exactly 21 inches long.

Many major luggage brands manufacture their standard overhead cabin bags to be exactly 21 inches tall to offer a balance between maximum storage and strict airline compliance.

The most common standard cutting width manufactured for walk-behind electric and gas lawn mowers is a 21-inch deck.

One of the most common standard sizes for a telescoping steel tactical baton used by law enforcement and security personnel is exactly 21 inches when fully extended.

In BMX bicycle sizing, a frame with a top tube length of exactly 21 inches is the standard "Pro" size designed specifically for adult riders taller than 5'8".

Standard hand-held tubular steel bow saws, commonly used for pruning trees and cutting firewood, frequently use a standard 21-inch replacement blade.

A 21-inch wheel rim is one of the most popular standard front-wheel sizes equipped on cruiser motorcycles and "baggers" to improve highway stability and visual aesthetics.

A traditional 21-inch display (measured diagonally from corner to corner) is a highly standard form factor for office desktop monitors.