It's about one-and-a-half times as long as an Aspirin.
In other words, the length of an Aspirin is 0.67 times 21.21 milimeters.(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 two-fifths as tall as a Golf Tee.
In other words, 21.21 milimeters is 0.39 times the height of a Golf Tee, and the height of a Golf Tee is 2.6 times that amount.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 twelve times as long as a Strand of Spaghetti (thickness).
In other words, the length of a Strand of Spaghetti (thickness) is 0.083 times 21.21 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 seventeen times as long as a Grain of Sand.
In other words, the length of a Grain of Sand is 0.0588 times 21.21 milimeters.(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 one-twentieth as tall as a Bowling Pin.
In other words, 21.21 milimeters is 0.0557 times the height of a Bowling Pin, and the height of a Bowling Pin is 18 times that amount.(USBC specifications; tenpin)
According to the United States Bowling Congress specifications, a tenpin bowling pin should be within 0.794 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.
It's about one-thirtieth as long as a Woman's Footstep.
In other words, the length of a Woman's Footstep is 31 times 21.21 milimeters.(for healthy, middle-aged woman of average height; single step length)
According to studies by The University of Oklahoma's Health Sciences Center, the average length of a woman's step is 660 milimeters, for an average stride (two-step's length) of 1,300 milimeters. The average person walks at a speed of about 1.3 m/s
It's about one-thirty-fifth as long as a Man's Footstep.
In other words, the length of a Man's Footstep is 37 times 21.21 milimeters.(for healthy, middle-aged man of average height; single step length)
According to studies by The University of Oklahoma's Health Sciences Center, the average length of a man's step is 790 milimeters, for an average stride (two-step's length) of 1,600 milimeters. The average person walks at a speed of about 1.3 m/s