Cloud+Base+Calculation

What is the calculation for Cloud Base?
How is the cloud base calculated in Virtual Weather Station?

Solution
Cloud Base (ft) = 250 * (Outdoor Temperature (ºF) - Dewpoint (ºF))

Example:

4120 ft = 250(31.5°F - 15.0 °F)

Cloud base is the difference in height from your current location and not sea-level. Please note that this is a calculation based on an estimate that clouds will form at a given altitude and does not measure the actual cloud height.