5/1 Arm Mortgage Payment

Can anyone find a reliable source or a know the formula to calculate the initial payment for a 5/1 arm
Leo TorresSQL DeveloperAsked:
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nickg5Connect With a Mentor Commented:
Hopefully that works for you!
Before trying to locate an answer for you let me tell you my experiences with 5-1 arm.
I was wanting a mortgage on a home under $50,000.
All the 5-1 arm did, was to give me a specific low interest rate IF I paid the mortgage off in the first 5 years. After that, the interest rate went up for the rest of the 30 year mortgage.
The 5-1 arm did not affect my mortgage payment, except the interest rate was lower those first 5 years.

What priced house can I use, for your scenario?


And are you wanting a 30 year mortgage or 15 year?

Is this a conventional loan, or FHA, or HUD?
Leo TorresSQL DeveloperAuthor Commented:

Conventional, 30 Years
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Here is an example from a site offering:
2.625% (3.054% APR) with an adjustable rate mortgage.

$200,000 loan amount, paying 1.75 points, with 30% equity on today’s rate
Over 5 years, a 5-year ARM at 2.625% could save you:

30-year fixed
3.99% (4.208% APR)
= $953 per month

5-year ARM
2.625% (3.054% APR)
= $803 per month

Leo TorresSQL DeveloperAuthor Commented:
OK so where is the formula.. I need a formula for getting these calculations not the calculations ai can get that from the site
5/1 ARM Fixed for 60 months, adjusts annually for the remaining term of the loan.

Here's another one:

You know the loan amount, and you know the interest rate your bank is quoting you.
Leo TorresSQL DeveloperAuthor Commented:
Are you reading my question.. I have the site I dont need site to calculate I Need the formula for the calculation
I am asking on a real estate-mortgage forum.
I'll post the replies when I get one.
With the complicated nature of these formulas, I am not sure if and when I'll get an answer from the mortgage forum.


The above is not for 5-1 arms, but you can see the complexity of the formulas.

If I get a reply from a mortgage specialist, I'll post it here for you.
Leo TorresSQL DeveloperAuthor Commented:
Ok these are better.. I had something similar to this and my client is getting something a bit different and the formula client gave is nothing like this one.. Guess I will see if your get something from your posting thank you
Mortgage lenders, and borrowers, frequent this real estate forum, so there are people there who know. It is just a matter of waiting on a reply.
Things on there may be slow until after the Monday holiday.
I got a couple replies and they are not encouraging:

1. (from a loan officer): Initial payment is determined by initial interest rate which is stated in your Note, it is not something that you calculate.

2. Do you use Excel?
Then use this function =pmt( ).
Instead, if you want an analytical function, I can provide you with one.

I've asked for the analytical function.......

so 2 replies after 18 lookers.
I got you another reply.

"No, you need a calculator.
You assume that the mortgage is fixed for 30 years, at the initial level of the ARM.
 If you really want a formula:
 Mortgage = sum of the (product of the per period payment x discount factor) for payments 1 to 360 (12 per year for 30 years) where the discount factor is calculated from the ARM interest rate.
Therefore the per period payment is backed out of this."

I can only go by what they tell me.

The guy says:

"The formula in the link is correct, and also applies to 5/1 ARMs for the first 5 years" (the formula from the link above)

That is about as much as I can find, at the moment.
Hopefully others can help you more.
Leo TorresSQL DeveloperAuthor Commented:
Guys I am trying to program thisn in SQL
SET @I = (@IntinalRate/ 1200)
SET @N = @Term*12

SET @APR_CALC_AMT = @Principle 
SET @APR_CALC_FEES = @Principle*(@Points/100)
SET @one_mo_int = @APR_CALC_AMT*@I
SET @totprin = 0

--Points are fees on a loan ie.. 1 point --> .01 x 100,000 = 1,000
SET @new_loan_amt = (@APR_CALC_AMT + @APR_CALC_FEES+@one_mo_int)+((@Points/100)*@APR_CALC_AMT)

SET @PnI_pmt2      = (@Principle*@I*POWER((@I+1),@N))/((POWER((@I+1),@N)-1))

Open in new window

Leo TorresSQL DeveloperAuthor Commented:
No Weird this is what They client is using in there own program that I have to move to SQL

arm_bal = new_loan_amt_orig - totprin
new_loan_amt_orig = new_loan_amt
new_loan_amt=( APR_CALC_AMT + APR_CALC_FEES + one_mo_int) + ((POINTS / 100)*APR_CALC_AMT)
one_mo_int=(APR_CALC_AMT * rate) / 1200
totprin = totprin + currentprin
currentprin = arm_pandi – currentint
arm_pandi = PnI_pmt
PnI_pmt =(new_loan_amt * (rate/1200))/(1-(1+(rate/1200))**(-Apr_term))
currentint = new_loan_amt*calcint
calcint = (rate / 1200)
fully_ndx_rate = Apr_margin + APR_index (both fields in the file)
adj_period = APR_TERM - new_arm_period

Not the same as I am seeing online
I'll post the above and see what the loan officer says.
Scott MadeiraConnect With a Mentor Commented:
What you show in your sample SQL looks like you are allowing for rolling in of closing costs and points and fees to get a total loan value and then calculate the payment.  As far as semantics go, what you are calling principle in your SQL is really loan amount.  Principle is the portion of your payment each month that reduces your mortgage balance.  Principle plus interest would equal your monthly payment.  

Here is a page of mortgage formulas...


For the 5/1 mortgage you would calculate your payment as if it were a 30-year conventional loan but use the 5-year fixed interest rate in your calculation.  The only thing the ARM does is give you a special / fixed interest rate for the first 5 years.  For the other 25 years of the loan the rate can change annually and usually has a cap on the rate that is ^% or 8% higher than the initial rate.  SO, if you get a 5/1 ARM at 4% the rate can adjust annually after the 5 years but it would never go above 10% regardless of market conditions in future years.
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