Estimating a difference in height between floors in a building for use in estimating a height or an altitude of one of the floors. A height difference is estimated between a first floor and a second floor based on outdoor temperatures of first and second time periods, an indoor temperature of the first or second time period, and first and second estimated differences in height between the first and second floors that is based on measurements of pressure from mobile devices when the mobile devices were on the first and second floors during the first and second time periods.