It's about 0.00000001 times as tall as a Mauna Loa.
In other words, 0.0039 inches is 0.00000001080 times the height of a Mauna Loa, and the height of a Mauna Loa is 92,590,000 times that amount.(Hawaii) (Hawaiian island volcano) (total height from seafloor)
Mauna Loa, one of the five volcanoes which forms the island of Hawaii and the tallest mountain in total height in the world, rises to 362,200 inches above the seafloor. The peak of Loa is home to the approximately 6,000 sq. m (0.6 ha) Lake Waiau, one of the highest altitude lakes in the United States outside of Colorado.
It's about 0.000000009 times as tall as The Challenger Deep (Marianas Trench).
In other words, 0.0039 inches is 0.00000000908640 times the height of The Challenger Deep (Marianas Trench), and the height of The Challenger Deep (Marianas Trench) is 110,050,000 times that amount.(near Marianas Islands, a.k.a. Ladrones Islands, northwestern Pacific Ocean) (depth below sea level)
The Challenger Deep, at the southern end of the Marianas Trench, reaches a depth of 429,210 inches below sea level. There has been only one manned expedition to the bottom of Challenger Deep — a 1960 voyage that took 4 hours and 48 minutes to reach the bottom.
It's about 0.000000009 times as tall as Maxwell Montes.
In other words, 0.0039 inches is 0.00000000900 times the height of Maxwell Montes, and the height of Maxwell Montes is 110,000,000 times that amount.(Ishtar Terra, Venus)
Maxwell Montes rises to a total height of 430,000 inches. Since Venus does not seem to have the kind of tectonic activity which gives rise to mountains on Earth, the origin of the Venusian mountain remains the subject of some dispute.
It's about 0.000000004 times as tall as Olympus Mons.
In other words, 0.0039 inches is 0.00000000370 times the height of Olympus Mons, and the height of Olympus Mons is 270,000,000 times that amount.(a.k.a. Mount Olympus) (Mars)
The tallest mountain in the solar system, Olympus Mons rises to approximately 1,100,000 inches. The mountain has been known to astronomers since the nineteenth century because it is tall enough to rise above Mars' frequent dust storms.
It's about 0.000000001 times as long as The Panama Canal.
In other words, 0.0039 inches is 0.00000000110 times the length of The Panama Canal, and the length of The Panama Canal is 910,000,000 times that amount.(Canal de Panamá) (Panama)
Connecting the Atlantic and Pacific Oceans across the Isthmus of Panama, the Canal measures 3,500,000 inches in length. Ships passing through the Canal are raised (and then lowered) 1,000 inches above sea level through the lock-and-dam system.
It's about 0.0000000010 times as long as The English Channel.
In other words, 0.0039 inches is 0.0000000009260 times the length of The English Channel, and the length of The English Channel is 1,080,000,000 times that amount.(average width between Isle of Ushant and The Walde Lighthouse) (La Manche, Ärmelkanal, Mor Breizh, Mor Bretannek) (a.k.a. The Channel)
The English Channel measures between 4,210,000 inches, narrowing as it flows northeast. The world speed record for a Channel crossing by swimmer was set by Australian Trent Grimsey in 2012, with a time of 6 hours, 55 minutes.
It's about 0.0000000009 times as long as The 405.
In other words, 0.0039 inches is 0.000000000850010 times the length of The 405, and the length of The 405 is 1,176,500,000 times that amount.(a.k.a. I-405, Interstate 405, San DIego Freeway) (Southern California)
Running from Irvine to San Fernando, The 405 runs a total of 4,588,200 inches. The 405 is the most heavily-trafficed freeway in the United States, with an average speed as low as 8 kph during rush hours.