Use the following formula to calculate the development project function point count. Notice there is an additional term CFP which is conversion function points. Often when a new application is replacing an old application, the data must be converted. Sometimes a "mini application" needs to be developed to assist in the conversion. This mini application does not exist after the new application is up and running. This is why development function point calculation is different the application function point count (see next below).
DFP = (UFP + CFP) * VAF