On Tue, 21 Aug 2007 16:40:22 -0700, joeu2004
sayd the following:

On Aug 21, 1:25 pm, Crackles McFarly wrote:
=fv(10%/12, 12*25, -100, -500)
Results in $21,838.02. Calculator result: $21,838. Where's the
error you are talking about?

A few of the online mutual fund investment calcs are different is what
I mean.

When I asked you to provide a URL for an online calculator, I meant
the URL of an online calculator that was giving different results,
"off by as much as 5%" you wrote.

I overstated that a bit. It was more like $1,200 out of $250K in a 25
year period which aint close to 5%..


But you are talking about mutual funds, not savings. I would not
estimate the "total return" over 25 years in that manner.

I'm told 8-12% is a good range, got to settle on one so I picked 10%
as an avg rate of return in the mutual funds arena.

I was not offering an opinion about your assumptions. Geesh, there
are enough pundits in these newsgroups already!

I was commenting on the methodology as it relates to estimating future
growth of mutual funds.

First, 10% is probably an APY. Therefore, the average monthly growth
rate is not simply 10%/12, which is used in the "dinkytown" savings
account calculator. Instead, it is (1+10%)^(1/12)-1 or
rate(12,0,-1,1+10%). (But sometimes RATE() has trouble determining an
answer unless we provide a "guess".)

Conversely, if you want use a simple calculator like "dinkytown", the
rate of return to use is 12*((1+10%)^(1/12)-1) -- approximately 9.57%.

Second, if mutual fund investment calculator computes "total
return" (I suspect it does), that might include an estimate of
reinvested dividends. That is the number used in prospectuses. That
complicates the computation enormously.

Yeah, none of these online calculators seem to take into account how
each month you take nothing OUT and simply grow by way of rates and
reinvesting your gains [which has to be a gigantic factor i'd think?]


HTH. I'm sure I have left off some other things.

It helped.. ;)