Observations of quiet day ionospheric electric fields from various middle- and low-latitude sources are analyzed by least squares fitting an electrostatic potential function to the data. The fit shows a reasonable amount of mutual consistency between the various data sources, but discrepancies point to the need for further study to delineat the universal time, seasonal, and day-to-day variations. Mapped into the magnetospheric equatorial plane, the electrostatic potential in the inner magnetosphere describes a plasma convection pattern on quiet days substantially different from that associated with a dawn-to-dusk electric field produced by solar wind-magnetosphere interactions.