It's about two-and-a-half times as wide as a Strand of Spaghetti
In other words, the width of a Strand of Spaghetti is 0.420 times 4 milimeters.(average; restaurant and supermarket applications) (based on FMA Omcan Italian Made TR50 Counter Top Pasta Machine Extruder 13317)
An average strand of restaurant-grade spaghetti measures 1.7 mm in thickness. In 2010, a California Buca di Beppo set a world record by preparing a 13,780-lb bowl of spaghetti, served in a swimming pool.
It's about three times as long as a Grain of Sand
In other words, 4 milimeters is 3.20 times the length of a Grain of Sand, and the length of a Grain of Sand is 0.3130 times that amount.(medium grain)
Composed mainly of quartz, mica, feldspar, or magnetite, a grain of sand measures an average of 1.25 mm. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 15,100 milimeters in height.
It's about three-tenths as long as an Aspirin
In other words, 4 milimeters is 0.290 times the length of an Aspirin, and the length of an Aspirin is 3.40 times that amount.(for up & up aspirin, 325mg, regular strength tablets) (a.k.a. acetylsalicylic acid, a.k.a. ASA)
A single aspirin tablet measures 14 mm in diameter. One of the most common medicines in the world and a foundation of worldwide health systems, an estimated 40,000 metric tons of aspirin are consumed each year.
It's about one-fifteenth as tall as a Golf Tee
In other words, the height of a Golf Tee is 14 times 4 milimeters.The most common golf tee size and the length preferred for iron and most wood clubs is 54 milimeters tall. The tee did not come into common use until it was promoted by professional golfers Walter Hagen and Joe Kirkwood, as part of a marketing effort by the patent-holder of the well-known, "Reddy Tee."
It's about 40 times as wide as a Strand of Hair
It's about 40 times as tall as a sheet of Paper
It's about one-ninety-fifth as tall as a Bowling Pin
In other words, the height of a Bowling Pin is 95.20 times 4 milimeters.(USBC specifications; tenpin)
According to the United States Bowling Congress specifications, a tenpin bowling pin should be within 0.7940 milimeters of 381 milimeters in height. The USBC further mandates that certified pins be made of sugar maple wood, unless otherwise approved by the organization.