Monthly extra principal
A smaller recurring amount reduces the balance a little earlier with every payment and is easy to compare with the normal monthly budget.
Principal reduction planning
Mortgage Extra Payment Calculator
Combine a regular monthly amount with an annual or one-time principal payment. The result keeps the required mortgage payment visible while showing how the balance, payoff date, and remaining interest may change.
Extra-principal strategy
See what an additional payment could change
Test monthly, annual, and one-time principal payments without changing the original loan terms.
Effect of the extra-principal plan
The required scheduled payment does not change; the balance falls faster.
New payoff estimate
Add a first payment month
8y 2m sooner
Estimated interest saved
$120,337
$262,297 interest with the plan
Scheduled payment
$1,896.20
Principal and interest before extra principal
Extra principal contributed
$65,491
Across the estimated payoff period
Current schedule versus new plan
Compare payoff time and remaining interest without changing taxes or insurance.
Current schedule
30 years to payoff
$382,633 interest
Extra-payment plan
21y 10m to payoff
$262,297 interest
Planning estimate
This model assumes a fixed-rate, fully amortizing mortgage and that extra amounts are applied directly to principal. Confirm payment-crediting rules and any prepayment penalty with the loan servicer.
Choose a strategy
The best extra-payment plan is one your budget can repeat
A large example can produce an impressive payoff date and still be a poor plan if it cannot survive a repair, an insurance increase, or a lean month. Start with the pattern that matches how money actually reaches the household.
Annual extra principal
This can model a predictable bonus, refund, or other yearly amount without assuming the cash is available every month.
One-time payment
Use this for money already available or expected in a particular month. The calculator does not assume that amount repeats.
Combined plan
The fields can work together, but each amount should have its own realistic source. Avoid counting the same bonus in both the annual and one-time fields.
Send it correctly
An extra payment helps only when it reaches principal as intended
The calculator applies every entered extra dollar directly to principal. The real loan follows the servicer's payment rules, so verify the instruction and then check the next statement.
PMI may be a second reason to monitor the balance
For eligible conventional loans, additional principal may help reach a borrower-requested PMI cancellation point sooner. The servicer can explain the loan's valuation, payment-history, and written-request requirements.
Use the principal-only option
If the servicer provides a separate field or instruction for additional principal, use it rather than simply increasing the payment without a designation.
Keep the scheduled payment current
Extra principal does not replace the required payment. Continue paying the contractual amount by its due date.
Review the next statement
Confirm that the principal balance fell by the expected amount and that the money was not held for a future installment.
Check large lump sums
Small additional principal payments do not normally trigger a prepayment penalty, but a large payment can be treated differently under some loan terms.
CFPB prepayment-penalty guidanceCalculation transparency
The comparison changes payment timing, not the original loan terms
The calculator first builds the scheduled loan, then runs a second monthly schedule with the selected principal additions. The difference between those schedules produces the estimated time and interest savings.
- 1
Build the original schedule
The remaining balance, note rate, and remaining term determine the required monthly principal-and-interest payment.
- 2
Apply extra principal by timing
Monthly additions are applied each month. Annual and one-time additions are applied only in their selected months and never replace the required payment.
- 3
Recalculate the declining balance
After an extra amount reduces principal, later interest is calculated from the smaller balance until the loan reaches zero.
- 4
Compare the two schedules
Months saved and interest saved are the differences between the scheduled loan and the accelerated plan. Taxes, insurance, fees, and investment alternatives are excluded.
Worked example
Combining monthly, annual, and one-time principal
This illustration shows why payment timing matters; it does not assume the same cash can fund more than one extra-payment field.
Assumptions
- Remaining balance
- $300,000
- Rate and remaining term
- 6.50% / 30 years
- Monthly extra
- $300
- Annual / one-time extra
- $1,000 / $5,000
Estimated result
- Scheduled payoff
- 30 years
- Estimated new payoff
- 18 years, 9 months
- Estimated time saved
- 11 years, 3 months
- Estimated interest saved
- $166,599
Confirm that the servicer applied every additional amount to principal. The result changes if an amount arrives later, is skipped, or is applied as a future installment.
Clear up the details
Common questions
Does an extra mortgage payment automatically go to principal?
Do not assume it will. Servicer procedures differ, and an additional amount may need a principal-only instruction. Check the payment screen or statement and confirm the servicer's process before relying on the projection.
Will extra principal lower my required monthly payment?
Usually not by itself. Extra principal can reduce the balance, future interest, and payoff time while the contractual payment remains unchanged. A formal recast, when available, is a separate process that may recalculate the required payment.
Which saves more: paying extra monthly or once a year?
When the same total amount is paid, sending principal earlier generally reduces the balance sooner and can save more interest. The practical choice is the schedule a household can sustain without weakening its cash reserve.
Can extra payments help remove PMI sooner?
For many conventional mortgages, extra principal may help the balance reach a PMI-cancellation threshold sooner. Cancellation is not automatic at every threshold and eligibility conditions apply, so contact the servicer and review the PMI disclosure.