What does paying extra buy me?
Extra payment calculator
Paying extra early is the highest-certainty return most households have available, and the size of it surprises people. Here is exactly how much, for your loan.
An overpayment is not an emergency fund. Money put into a mortgage is very hard to get back out, and this calculator does not weigh that against you.
Your inputs
A bonus in month 13, an inheritance in month 40 — the month matters, because early money avoids more interest.
Which month of each year it lands in.
Your result
Interest avoided
$129,824
6 years off the term
Side by side
What it costs you
The gap between the curves is equity you own earlier.
The accelerated line stops climbing sooner, and lower.
The schedule
The accelerated schedule. The extra column shows what you added; the balance column shows what it did.
| Month | Payment | Interest | Principal | Insurance | Balance | Interest to date |
|---|
Take this with you
Every number you entered is in the address bar. Copy the link and it opens with your inputs restored — that is how everything else here shares.
What this assumes
- Every extra dollar is applied to principal in the month it is paid, and the servicer applies it correctly. Ask: some apply it to the next payment instead, which does nothing.
- No prepayment penalty. Most modern conforming loans have none, but non-QM and investor loans sometimes do — check the note.
- The return figure is interest avoided divided by extra paid. It is a total ratio, not an annualised rate.
- Overpaying does not reduce your required monthly payment; it shortens the term. If you want a lower payment you need a recast or a refinance.
Demonstration form
Have someone look at it
If this were a working site, this is where the conversation would start.