US Unit Conversion: Distances, Elevation, Area, Speed

The highest point in the United States is Denali in Alaska, rising to 6 190 metres above sea level. That is 20 308 feet, a figure that matters for anyone planning a climb and needing to understand altitude. The conversion is exact: one metre equals 3.28084 feet, and one foot equals 0.3048 metres. For a quick mental estimate, multiply metres by 3.3 to get feet, or divide feet by 3.3 for metres. For precise values, use a converter for feet to metres before you finalise any travel plans.

The United States uses US customary units in everyday life: miles for distance, feet for elevation, square miles for area, degrees Fahrenheit for temperature, and miles per hour for speed. The straight-line distances between the capital and the farthest postcode localities show this dual need clearly. These are great-circle distances, not road distances, meaning they represent the shortest possible air miles between two points.

Distances from Washington, D.C. to the Postcode Extremes

The northernmost postcode locality is Barrow (99723), lying 5 592 kilometres from the capital. That equals 3 475 miles. To convert in your head, remember that 1 mile equals 1.609344 km, or roughly 1.6. Multiply miles by 1.6 for kilometres, or divide kilometres by 1.6 for miles. The southernmost postcode locality, Naalehu (96772) in Hawaii, is 7 728 km away, which is 4 802 miles. The easternmost postcode, Eastport (4631) in Maine, is 1 065 km (662 mi) from the capital. The westernmost, Adak (99546) in the Aleutian Islands, sits 7 289 km (4 529 mi) away. For exact figures, a miles to kilometres converter ensures accuracy on any flight plan.

Consider the span between the extremes themselves. The northernmost postcode, Barrow (99723), to the southernmost, Naalehu (96772), is 5 801 km straight-line. That is 3 605 miles. The easternmost postcode, Eastport (4631), to the westernmost, Adak (99546), measures 7 326 km, or 4 552 miles. These are not driveable distances; they are great-circle arcs across the continent and Pacific. When you see a road sign in Maine saying “Adak 4 552 mi,” you know the conversion is exact, but your odometer will never cover that path.

Area and Elevation Conversions

The total area of the United States is 9 826 675 square kilometres. That is 3 794 100 square miles. To convert, remember that 1 square mile equals 2.589988 square kilometres, and 1 square kilometre equals 0.386102 square miles. A quick mental trick: divide square miles by 2.6 for square kilometres, or multiply square kilometres by 0.39 for square miles. For precise land calculations, use a square miles to square kilometres converter. Elevation follows the same logic. Denali’s 6 190 m becomes 20 308 ft, using the exact factor of 0.3048 m per foot. Multiply feet by 0.3048 for metres, or metres by 3.28084 for feet.

The international standard for these units comes from the BIPM, the international body that defines the SI units. That organisation defines the metre and the kilogram, from which all metric conversions flow. For US-specific guidance, the NIST guide to metric and US customary conversion provides a practical reference for everyday use. Both sources agree on the exact factors, so you can trust the numbers whether you are measuring a postcode distance or a mountain height.

Speed and Temperature Quick Reference

Speed in the US is expressed in miles per hour. The conversion factor is exact: 1 mph equals 1.609344 km/h. To convert in your head, multiply mph by 1.6 for a close km/h value. For example, 50 mph is 80 km/h. Here are the common reference points, computed exactly:

  • 30 km/h = 18.6 mph
  • 50 km/h = 31.1 mph
  • 80 km/h = 49.7 mph
  • 100 km/h = 62.1 mph
  • 120 km/h = 74.6 mph

Temperature is another daily conversion. The formula is: degrees Fahrenheit = degrees Celsius x 9/5 + 32. So 0 °C is the freezing point of water, which is 32 °F. A warm day at 30 °C is 86 °F. Body temperature is 37 °C, or 98.6 °F. Boiling water is 100 °C, which is 212 °F. For a precise conversion without mental arithmetic, use a Fahrenheit to Celsius converter. Speed and temperature both come up on every road trip, and the same rule applies: if you are driving from Barrow to Naalehu, you will see miles per hour on the signs, but your car’s computer might show kilometres per hour. For that, a mph to km/h converter is your co-pilot.

So the next time you look at a map of the United States, remember the numbers. The capital to Barrow is 3 475 miles. The capital to Naalehu is 4 802 miles. Eastport to Adak is 4 552 miles. And the highest point, Denali, is 20 308 feet. All of these are exact conversions from metric, and all of them are easier to grasp when you know the simple factors: 1 mile = 1.609344 km, 1 foot = 0.3048 m, 1 square mile = 2.589988 km². Knowing both is not just useful; it is the only way to make sense of a country that spans 3 794 100 square miles and 6 190 vertical metres.