This article describes the formula syntax and usage of the GROWTH function in Microsoft Excel.
Description
Calculates predicted exponential growth by using existing data. GROWTH returns the yvalues for a series of new xvalues that you specify by using existing xvalues and yvalues. You can also use the GROWTH worksheet function to fit an exponential curve to existing xvalues and yvalues.
Syntax
GROWTH(known_y's, [known_x's], [new_x's], [const])
The GROWTH function syntax has the following arguments:

Known_y's Required. The set of yvalues you already know in the relationship y = b*m^x.

If the array known_y's is in a single column, then each column of known_x's is interpreted as a separate variable.

If the array known_y's is in a single row, then each row of known_x's is interpreted as a separate variable.

If any of the numbers in known_y's is 0 or negative, GROWTH returns the #NUM! error value.


Known_x's Optional. An optional set of xvalues that you may already know in the relationship y = b*m^x.

The array known_x's can include one or more sets of variables. If only one variable is used, known_y's and known_x's can be ranges of any shape, as long as they have equal dimensions. If more than one variable is used, known_y's must be a vector (that is, a range with a height of one row or a width of one column).

If known_x's is omitted, it is assumed to be the array {1,2,3,...} that is the same size as known_y's.


New_x's Optional. Are new xvalues for which you want GROWTH to return corresponding yvalues.

New_x's must include a column (or row) for each independent variable, just as known_x's does. So, if known_y's is in a single column, known_x's and new_x's must have the same number of columns. If known_y's is in a single row, known_x's and new_x's must have the same number of rows.

If new_x's is omitted, it is assumed to be the same as known_x's.

If both known_x's and new_x's are omitted, they are assumed to be the array {1,2,3,...} that is the same size as known_y's.


Const Optional. A logical value specifying whether to force the constant b to equal 1.

If const is TRUE or omitted, b is calculated normally.

If const is FALSE, b is set equal to 1 and the mvalues are adjusted so that y = m^x.

Remarks

Formulas that return arrays must be entered as array formulas after selecting the correct number of cells.

When entering an array constant for an argument such as known_x's, use commas to separate values in the same row and semicolons to separate rows.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Month 
Units 
Formula (Corresponding Units) 

11 
33,100 
32,618 

12 
47,300 
47,729 

13 
69,000 
69,841 

14 
102,000 
102,197 

15 
150,000 
149,542 

16 
220,000 
218,822 

Month 
Formula (Predicted Units) 
Formula used in C2:C7 array above 

17 
320,197 
=GROWTH(B2:B7,A2:A7) 

18 
468,536 

Formula used in B9:B10 array above 

=GROWTH(B2:B7,A2:A7,A9:A10) 