Extra payment curve you can drag
Drag extra monthly principal along the curve. Months remaining fall fast at first and then flatten, which is why the first extra dollars buy more time than the later ones. The default is an extra $200 a month on a $300,000 loan at 6.5 percent over 30 years.
Months saved
83
Interest saved
$103,449
Drag the dot along the curve. Illustrative run on a $300,000 loan. Extra is applied to principal on top of the scheduled payment. Nothing here is a forecast or advice.
- Scheduled payment
- $1,896.20
- Payment with extra
- $2,096.20
- Original term
- 360 months
- Interest if paid as scheduled
- $382,633.47
In short
- Drag the dot right to raise the extra principal, left to lower it.
- Read months saved and interest saved above the chart; they move together and they flatten.
- Use the rate and term sliders under the chart if you want a different original loan, still on the same $300,000 principal.
Why the curve flattens
An amortising payment is mostly interest at the start and mostly principal at the end. Extra principal takes months off the far end, where the scheduled payment was already principal-heavy. The first extra dollars remove a long, expensive tail. Later extra dollars remove a shorter tail. That is a logarithm, and it is why doubling the extra is not twice the decision.
What is held still
The principal is a fixed $300,000 so the extra is the only thing moving the curve under your finger. Rate and original term can be changed with the sliders; they rescale the picture rather than dragging it. For the same arithmetic as a table of two schedules, use the mortgage extra payment calculator.
What the extra is not
It is not a cut to the required payment, and it is not advice to prepay rather than invest. The picture names the months and the interest that come off this loan if the extra actually arrives every month. Whether those dollars should be the extra is a different question.
Common questions
Why can I not drag the principal?
Because then two things would move at once and the flattening would be harder to see. The extra-payment calculator lets you type any principal. This picture is for the shape.
Does extra principal cut my required payment?
Not on a standard fixed-rate loan. The scheduled payment stays put; the term shortens. Recasting is a separate request some servicers offer, and it is not what this curve draws.
Is this a forecast of my loan?
No. It is the arithmetic of one constant extra on one constant-rate loan. Illustrative figures, educational material, not advice.
Keep reading
This page is educational material, not financial advice. The figures come from the formula shown and assume the inputs you enter hold for the whole term. Your own rate, fees, taxes and timing will differ, so treat the output as arithmetic to check a decision against, not as a recommendation.