# Performing Conversions

*Go Up to Converting Measurements*

You can use the Convert function to perform both simple and complex conversions. It includes a simple syntax and a second syntax for performing conversions between complex measurement types.

## Performing simple conversions

You can use the *Convert* function to convert a measurement from one set of units to another. The *Convert* function converts between units that measure the same type of thing (distance, area, time, temperature, and so on).

To use *Convert*, you must specify the units from which to convert and to which to convert. You use the TConvTypetype to identify the units of measurement.

For example, this converts a temperature from degrees Fahrenheit to degrees Kelvin:

**Delphi:**

```
TempInKelvin := Convert(StrToFloat(Edit1.Text), tuFahrenheit, tuKelvin);
```

**C++:**

```
TempInKelvin = Convert(StrToFloat(Edit1->Text), tuFahrenheit, tuKelvin);
```

## Performing complex conversions

You can also use the *Convert* function to perform more complex conversions between the ratio of two measurement types. Examples of when you might need to use this this are when converting miles per hour to meters per minute for calculating speed or when converting gallons per minute to liters per hour for calculating flow.

For example, the following call converts miles per gallon to kilometers per liter:

**Delphi:**

```
nKPL := Convert(StrToFloat(Edit1.Text), duMiles, vuGallons, duKilometers, vuLiter);
```

**C++:**

```
double nKPL = Convert(StrToFloat(Edit1.Text), duMiles, vuGallons, duKilometers, vuLiter);
```

The units you are converting must be in the same conversion family (they must measure the same thing). If the units are not compatible, *Convert* raises an *EConversionError* exception. You can check whether two *TConvType* values are in the same conversion family by calling CompatibleConversionTypes.

The System.StdConvs unit defines several families of *TConvType* values.