# Empirical formula

An empirical formula is a mathematical relationship that has been discovered empirically , i.e. using the method of trial and error , or established from experimental data as an approximate formula . As a result, at the time of its discovery, it generally had no theoretical justification from which it could have been deductively derived.

In particular, these are also formulas that have no direct unit relationship between the values to be used and the resulting quantities . In individual cases, therefore, additional instructions for the empirical formulas define the units. This is expressed in the fact that you have to convert the quantities to be used into a certain unit and then only have to enter their numerical values ( numerical value equation ). The resulting numerical value must then be assigned to a unit that does not result from the equation itself and must therefore also be taken from the side remarks.

Such equations are particularly widespread in engineering and hydrology , but also in numerous other natural sciences.

Examples: