mortgage early payoff?

No one can tell you when you will have equity because no one can accurately predict the value of your home in six months, one year, two years, five years, etc.

You can very easily figure out what your loan balance would be at any given point in time by using an amortization schedule and plug in your extra principal payments. If you have Microsoft Office, Excel has a built-in amortization schedule.

If you want a quick ball park, figure out how much of your 475 is principal, add that amount to 450 and that's how much you will reduce your loan balance each month. You will then be able to easily see a rough estimate of what your loan balance will be in one year, two years, five years, etc. Keep in mind that the amount of principal you pay goes up (and interest goes down) a tiny bit with each payment you make.

A year, roughly.

you're 8200 upside down; about 275 of each payment of 475 is for interest. so 200 + 450 each month will go towards principal; that's 650 per month. 8200 / 650 = 12.6 months. let's assume actual home value will improve some over the next few months, that can help get you out of the hole sooner.

the 275 comes from a (7.75/12)% monthly interest charge, times 42200.

everything of your mortgage payment that applies to the principle increases your equity, if you pay another $450 each month to the principle only that will increase your equity another $5400 a year(at this rate it would take about 6 yrs)

If you pay $450.00 per month extra principal you will be even in about 9 months.

As soon as you get a bit above-water, you should apply to refinance the mortgage. 7.75% these days is about double the going rate.