You have some cash and a mortgage. Now what?
Six things you could do, on one screen, using one set of numbers. Most calculators handle exactly one of these and make you re-enter everything to see the next.
Your loan today
Principal and interest only — leave out taxes, insurance and PMI. The remaining term is worked out from your balance, rate and payment, so extra payments you've already made are accounted for.
What you're considering
| Scenario | Required | Change | You send | Paid off | Interest left | Total cash out |
|---|
What the options actually are
Prepaying means throwing the cash at principal and carrying on. Your payment doesn't change, so the loan just ends earlier. It costs nothing and saves the most interest.
Recasting means paying down principal and asking your servicer to re-amortize the smaller balance over your remaining term. Your rate and payoff date stay put; the required payment drops. There's usually a few hundred dollars in fees. A recast cannot change your interest rate.
Refinancing replaces the loan, which is the only one of these that changes your rate. A cash-in refinance brings money to closing at the same time, reducing the balance and possibly moving you into a better loan-to-value tier.
The setting that changes everything
Above the results there's a toggle for what you'll send afterwards. If your required payment drops and you keep sending the same dollar amount, the extra goes to principal and the loan dies years earlier. If you drop to the new minimum, it doesn't. Same lump sum, same fee, same rate, wildly different outcomes. Flip it and watch the payoff dates move.
Two loan-to-value numbers, not one
Refinance pricing steps at 80%, 75% and 60% loan-to-value, and PMI ends at 80%. But conventional PMI cancels against your original purchase price, while a refinance is priced against a new appraisal. If your home has appreciated, those two numbers can be far apart, and the meter above shows both.
What this doesn't model
It ignores what the cash could have earned somewhere else. That matters enormously: against a 3% mortgage, putting money into principal is a poor trade compared with almost any alternative, and no amount of interest saved changes that. It also assumes you qualify. FHA, VA and USDA loans generally can't be recast, and servicers set their own minimum lump sums and fees, so confirm what yours allows before planning around it.
Servicers also drop PMI automatically only at 78% on your original schedule, ignoring extra payments entirely. If you've been paying ahead you'll reach real 80% well before that, and you have to call and request it. Most people never do.