It's about as wide as a Strand of Hair
It's about as tall as a sheet of Paper
It's about one-tenth as long as a Grain of Sand
In other words, 0.004 inches is 0.0813 times the length of a Grain of Sand, and the length of a Grain of Sand is 12.30 times that amount.(medium grain)
Composed mainly of quartz, mica, feldspar, or magnetite, a grain of sand measures an average of 0.0492 inches. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 594 inches in height.
It's about fourteen times as long as a Red Blood Cell
In other words, the length of a Red Blood Cell is 0.071 times 0.004 inches.(a.k.a. RBCs, a.k.a. haematids, a.k.a. erythrocyte, a.k.a. erythroid cells, a.k.a. red blood corpuscles)
An average Red Blood Cell measures 7.5 µm (micrometers) in diameter. An average human has 20 - 30 trillion red blood cells in their body and each cell completes a circulatory lap in about 20 seconds.
It's about one-fifteenth as wide as a Strand of Spaghetti
In other words, the width of a Strand of Spaghetti is 17 times 0.004 inches.(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 0.067 inches 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 Cell's Nucleus
In other words, the length of a Cell's Nucleus is 0.059 times 0.004 inches.(for animal cell)
The nucleus of an animal cell measures an average of 0.00024 inches. The nucleus is the largest organelle in these cells, accounting for about 10% of the cell's total volume.
It's about 50 times as long as a Bacterium