Hi Mark!
Adjusted formula for the range you reported privately and to allow for
blanks in the data range:
=SUM(IF(ISBLANK(H2:H500)=FALSE,DATEDIF((H2:H500),TODAY(),"y")))+INT(SUM(IF(ISBLANK(H2:H500)=FALSE,(DATEDIF((H2:H500),TODAY(),"ym"))))/12)&"
years
"&MOD((SUM(IF(ISBLANK(H2:H500)=FALSE,(DATEDIF((H2:H500),TODAY(),"ym"))))+INT(SUM(IF(ISBLANK(H2:H500)=FALSE,(DATEDIF((H2:H500),TODAY(),"md"))))/(365.25/12))),12)&"
months
"&ROUND(MOD(SUM(IF(ISBLANK(H2:H500)=FALSE,(DATEDIF((H2:H500),TODAY(),"md")))),365.25/12),0)&"
days"
You might find it better to break it up into helper formulas
especially if there are any further complications.