A little info in addition to Fred's post:

*Typically* the amount of interest you get charged is based on the average
balance of the loan for the billing period - typically a calendar month. The
average balance takes into account the number of days the account is at a
particular balance and the number of days in the month. Thus, assume your
loan has a balance on the 1st of the month of $5,000. You draw out more
money on the 8th, say $500, and make a $750 payment on the 15th. Assume a 31
day month.

So, the balances are as follows:
$5,000 - 7 days (1st thru the 7th)
$5,500 - 7 days (8th thru 14th)
$4,750 - 17 days (15th thru the 31st)

so... the average balance for the month is

[ (7*5000)+(7*5500)+(17*4750) ]/31 days = $4,976

The final question is how does the lender charge interest? Is it on an
Actual/Actual or a 30/360 or even an Actual/360. There are others too, some
less common than others, but the portion to the left of the / sign indicates
how you count the days in the month, while the portion to the right indicates
how you count the days in the year. That dictates how the annual rate is
translated into a monthly rate. So, in the case of Actual/Actual, your 5.49%
annual rate becomes a monthly rate of .466% (5.49%*31/365) and in the case of
30/360 it becomes a monthly rate of .458% (5.49%*30/360). If you apply those
rates to the average balance calculated above, $4,976, the monthly interest
charges are $23.20 and $22.76, respectively.

"Titanium" wrote:

I know this may be a bit of a 'big one' but, I really need a calculator that
will allow me to have a fixed interest rate, and then allow me to enter
payments or withdrawls to determine the current balance of the line of
credit. Anyone up for making such a beast for me? I am just horrendus at
loans and that sort of thing.
I don't know if for example withdrawing money at mid month affects the
actual interest rate or not, or paying late, but frankly i'm not worried
about _that much_ accuracy. Just the calculations.

I was thinking A2 would be the interest rate: 10.9%, A5 could be the start
of the dates, B6 could be the first withdrawl from the line of credit. C6
would be blank? as not one month has past but B7 would be the payment made,
or withdrawl again, C7 would be the current full amount due with interest and
so on.

Anyone up for this? I really just need the formula to put in the C column. :)
I could really use your assistance on this.

Please and thank you? :) *SMiLe*