# Definition:FPS

## Definition

FPS is the foot-pound-second standard system of units of measurement.

It is derived from the imperial system, and was used throughout the British Empire until the mid-20th century.

## FPS Base Units

FPS base units
Name Unit symbol Dimension Symbol
foot $\mathrm {ft}$ Length $l$
pound $\mathrm {lb}$ Mass $m$
second $\mathrm s$ Time $t$

### Foot

The foot is the FPS base unit of length.

 $\displaystyle$  $\displaystyle 1$ foot $\displaystyle$ $=$ $\displaystyle 12$ inches $\displaystyle$ $=$ $\displaystyle 30.48$ centimetres $\displaystyle$ $=$ $\displaystyle 0 \cdotp 3048$ metres

### Pound

The pound is the FPS unit of measurement of mass, which has a number of different standards.

The most common standard is for it to be defined in kilograms to be exactly $0.453 \, 592 \, 37 \ \mathrm{kg}$.

### Second

The second is the SI base unit of time, and also therefore of the MKS system.

It is also the base unit of time for the FPS and CGS systems.

The second is defined as:

the duration of $9 \ 192 \ 631 \ 770$ periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium $133$ atom at rest at $0 \ \mathrm K$.

## Historical Note

The FPS system is rarely seen nowadays, as most nations have converted to the SI system based on the metre-kilogram-second base units.

As there are several systems similar to this one, some of which use the same name for subtly different standard units, the use of SI units is strongly encouraged.

The imperial system, upon which it was based, continues to be used in domestic commerce and trade in some parts of the world.

## Also denoted as

Some sources render this as f.p.s.