Clara,
I think you mean "the number of characters a control can display." The numbers of
characters a control can "contain" is determined by the field length definition in the
table design.
It's not really "calculable" because, not only can fonts effect that, but also the
specific characters in the data values.
A 1" wide text control might display 10 "A" Arial characters, while a QuickType
Condensed would display say.. 14 or 15 "A"s in that same control. But that same control
might be able to display 15 "i" Arial characters, and maybe 8 "M" Arial characters.
--
hth
Al Campagna . Candia Computer Consulting . Candia, NH USA
Microsoft Access MVP
http://home.comcast.net/~cccsolutions
"Find a job that you love, and you'll never work a day in your life."