Dimensional analysis for obtaining a quantity in units of Celsius from units of Fahrenheit; one could have started with the equivalence between 100 °C and 212 °F, though this would yield the same formula at the end. Hence, to convert the numerical quantity value of a temperature "T"[F] in degrees Fahrenheit to a numerical quantity value "T"[C] in degrees Celsius, this formula may be used: To convert "T"[C] in degrees Celsius to "T"[F] in degrees Fahrenheit, this formula may be used: Dimensional analysis is most often used in physics and chemistry – and in the mathematics thereof – but finds some applications
Fahrenheit Canadian ovens make legal use of the Fahrenheit scale. Thermometers, both digital and analog, sold in Canada usually employ both the Celsius and Fahrenheit scales. Also, in some instances (swimming pool temperature, thermostats, or cooking temperatures for example), temperatures are still expressed in Fahrenheit. Within the European Union, it is mandatory to use kelvins or degrees Celsius when quoting temperature for "economic, public health, public safety and administrative" purposes, though degrees Fahrenheit may be used alongside degrees Celsius as a supplementary unit. For example, the laundry symbols used in the United Kingdom follow the recommendations of ISO 3758:2005 showing the