Number conversion between different units of measurement in a document is enabled. A string of text entered into an application program is analyzed to determine whether it includes a number having an associated unit name. Found numbers with associated unit names are semantically labeled with schema information identifying the unit name as a source unit of measurement. When the number is selected or an indication received that the number is labeled with schema information, a list of actions may be provided identifying conversion options for the number. In response to selection of one of the conversion options, the selected number is converted to the destination unit of measure identified by the selected action. The converted number may then be inserted into the string of text to replace the selected number along with a unit name corresponding to the destination unit of measure.