On Aug 20, 12:50 pm, Crackles McFarly wrote:
I was needing a formula in EXCEL to calculate the future value based
on initial investment, number of years AND regular investments of $XXX
per month during the years.

I've tried several formulas, they give neg numbers

The negative results might be due to the fact that the formulas
require that inflow and outflow have opposite signs; and you can
choose the signs arbitrarily (i.e. negative or positive for inflow,
and the opposite sign for outflow) so that the function result is
always positive. But in this case, FV() should return a positive
value if you use the correct sign for the input parameters from the
investor's point of view, namely negative initial investment and
negative periodic investments (payments). For example, consider an
initial investment of $10,000 and monthly investments of $100, with a
return of 1% per month compounded over 5 years.

=fv(1%, 12*5, -100, -100000)

This results in the (correctly) positive value of $189,836.64
(rounded).

or results that do
NOT seem the same as online calulators, off by as much as 5%!

There can be many explanations for such differences. One that comes
to mind is differences in determining the monthly rate of return based
on an annualized rate.

If you provide the URL for one or more of the online calculators, I
might be able to provide a more specific (and perhaps more correct)
explanation.