Returns the smallest valid non-blank value in field.
field - any related field, repeating field, or set of non-repeating fields; or an expression that returns a field, repeating field, or set of non-repeating fields.
Parameters in curly braces { } are optional.
Data type returned 
text, number, date, time, timestamp
Originated in 
FileMaker Pro 6.0 or earlier
Field can be any of the following:
a repeating field (repeatingField).
a field in matching related records specified by (table::field), whether or not these records appear in a portal.
several non-repeating fields in a record (field1;field2;field3...).
corresponding repetitions of repeating fields in a record (repeatingField1;repeatingField2;repeatingField3), if the result is returned in a repeating field with at least the same number of repeats.
several fields in the first matching record specified by (table::field1;table::field2;...). You can include fields from different tables (table 1::field A;table 2::field B...).
A Contracts table has a portal showing bids submitted for each contract.
Min(Bids::Price) returns the lowest bid submitted for a contract.
In the following examples:
Min(Field2) returns 5 when the calculation isn’t a repeating field.
Min(Field1;Field2;Field3) returns 1, 2, 7, 8 when the calculation is a repeating field.
When a referenced field is a repeating field, the Min function returns the minimum value in the first repetition field, then the minimum value in the second repetition field, and so on.
Aggregate functions such as Min or Max use the data type of the first parameter to perform all comparisons. For example, if the first parameter’s data type is text, all other parameters are converted to text and then compared.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas