Mils (NATO) to Seconds of Arc Converter

What Is a Mil?

A mil, short for milliradian, is equal to 1/6,400 of a circle. The mil used by the US military and NATO forces is slightly different than the true value of a milliradian, which is equal to 1/6,283 of a circle.

During World War I the US adopted what is now the NATO mil to replace degrees and minutes for use in artillery sights. They opted to round mils to 6,400 per circle for simplicity at the time. Today, the mil is commonly used to measure adjustment of sights and scopes of firearms.

There is rightfully much confusion as a result of the mil adopted by the US military and NATO being slightly different than the milliradian.

A mil is sometimes also referred to as an angular mil. Mils can be abbreviated as mil; for example, 1 mil can be written as 1 mil.

Learn more about mils.

What Is a Second of Arc?

The second of arc is a unit of angle equal to 1/60th of one minute of arc or 1/3,600 of one degree.

A second of arc is sometimes also referred to as an arc second or arcsecond. Seconds of arc can be abbreviated as arcsec, and are also sometimes abbreviated as asec. For example, 1 second of arc can be written as 1 arcsec or 1 asec.

The second of arc is most commonly expressed using a double prime (″), though a double quote is often used as well. For example, 1 second of arc is most often written as 1″.

Learn more about seconds of arc.