Advanced Mortgage Calculator?

[Cliff T.]

Hi BP,

I have just given up on google and am turning to you guys for help.

I would like to know if there is a mortgage calculator out there that allows you to input your past payments and potential future payments?

I want to see how much money I'm really saving on each payment that has more than the minimum balance going towards principle.

If you feel like getting technical, allow me to explain my current situation that gave the desire to find such a calculator:

I'm getting a HELOC on my primary residence. It's 1.99% and has no closing costs*.

* = So long as I use a minimum $10k of the $20k for the entire first year. 

At first, I thought well there goes my free closing costs... Because I won't need to use that much all year. 

BUT THEN I had an idea: What if I just put $10k of my HELOC on my primary mortgage towards principle? My primary mortgage is 2.5% for 5 years, then goes up 1% or so every 2 years. I'm still in year 1.

I'd like to see the actual numbers so I can determine whether or not this would be a wise decision.

Any and all feedback is both welcome and MUCH appreciated!

Sincerely,

Cliff