Hectopascals to millimeters of mercury converter above calculates how many millimeters of mercury are in 'X' hectopascals (where 'X' is the number of hectopascals to convert to millimeters of mercury). In order to convert a value from hectopascals to millimeters of mercury (from hPa to mmHg) just type the number of hPa to be converted to mmHg and then click on the 'convert' button.