Fifteen years in, you still owe $260,861. Halfway through the term, only a quarter of the debt has cleared. That single fact drives most extra-payment plans.
Find your own row on any monthly statement. The split printed there matches this table's logic exactly. Only the numbers differ.
Biweekly payment plans promise a trick. Half a payment every two weeks adds one full payment per year.
Copy it yourself with monthly extras. Skip the enrollment fee some servicers charge. The schedule cannot tell the difference.
How much do extra payments actually save?
Small monthly extras produce shocking totals at 7.18%.
Send $200 more each month and the payoff arrives 6.4 years early. Total interest drops to $376,139.21. That saves $127,428.68 against the base schedule.
Extra monthly payment effects on the $350,000 loan at 7.18%| Extra monthly | Payoff time | Total interest | Interest saved |
|---|
| $0 | 30.0 years | $503,568 | none |
| $100 | 26.3 years | $428,950 | $74,618 |
| $200 | 23.6 years | $376,139 | $127,429 |
| $300 | 21.4 years | $336,225 | $167,343 |
| $400 | 19.8 years | $304,732 | $198,836 |
The balance gap widens fast too. After 15 years the base loan still owes $260,861. The $200-extra version owes $196,467 by then.
Balance left: base versus $200 extra monthly| Year | Base balance | With $200 extra | Gap |
|---|
| 1 | $346,566 | $344,086 | $2,480 |
| 5 | $330,087 | $315,701 | $14,386 |
| 10 | $301,603 | $266,641 | $34,962 |
| 15 | $260,861 | $196,467 | $64,394 |
| 20 | $202,585 | $96,093 | $106,492 |
One-time lump sums work the same way. A bonus applied to principal acts like many extra months at once. The tables above still forecast it, month for month.
Start small if the full table scares you. Even $75 monthly saves $58,525 on this loan and clears it 2.8 years early. Consistency beats size over 30 years.
One rule makes all of this work. The extra must be applied to principal. Source: Consumer Financial Protection Bureau, November 2026.
Which is better: extra payments or a 15-year loan?
The 15-year loan forces discipline; extra payments keep freedom.
At 6.57%, the November 2026 15-year rate, the same loan costs $3,062.36 monthly. Total interest runs $201,224.89. Source: Freddie Mac survey data, November 2026.
The 30-year with $569 extra monthly matches that payment almost exactly. It also lets you drop back to $2,371.02 in a tight month. The forced 15-year schedule has no pause button.
Two routes on $350,000, November 2026 rates| Route | Monthly cost | Total interest | Flexibility |
|---|
| 15-year at 6.57% | $3,062 | $201,225 | None, fixed |
| 30-year at 7.18% plus $569 | $3,040 | about $218,000 | Pause anytime |
| 30-year at 7.18% plain | $2,371 | $503,568 | Full |
Refinancing also brings closing costs, often thousands up front. Extra payments carry no fees at all. Spread over years, that difference matters.
A recast offers a middle path. Pay a chunk of principal, then re-amortize the same loan. The payment drops without a refinance, though the rate stays.
Shopping either route? Compare offers first; our guide to the best-rated mortgage lenders lists what to check. Rate history also helps; see where 30-year rates stood in September 2026.
How do taxes and PMI change the picture?
Escrow costs sit outside the schedule, but they crowd your budget.
Your lender may collect property taxes and insurance in the same monthly payment. That escrow money never touches the balance. The amortization table tracks principal and interest only.
Budget from the full monthly debit, not the schedule minimum. Extras only stick when the total payment stays comfortable.
PMI works differently. Once your equity crosses 20%, PMI can drop off. Extra payments reach that line years sooner, freeing budget for more principal.
- Escrow items never reduce your balance.
- PMI ends sooner when principal drops faster.
- Plan extras from the full monthly debit.
- Ask your servicer where PMI removal starts.
PMI often costs thousands each year on a loan this size. Killing it early frees real money for principal. Ask your servicer exactly when the 20% equity line gets crossed.
Where can you build your own schedule for free?
One spreadsheet function replaces every paid calculator.
Open Google Sheets or Excel. A free amortization schedule calculator with extra payments takes ten minutes this way.
- Type your loan amount in cell A1, say 350000.
- Add your yearly rate in A2 and your term months in A3.
- Compute the payment with =PMT(A2/12, A3, -A1).
- Build row one: month, payment, interest, principal, extra, balance.
- Enter interest as =balance*A2/12 and principal as payment minus interest.
- Set the next balance as prior balance minus principal minus extra.
- Copy the row down 360 rows and watch it fill.
Spreadsheet formulas for your schedule| Task | Formula |
|---|
| Monthly payment | =PMT(7.18%/12, 360, -350000) |
| Month interest | =balance*7.18%/12 |
| Month principal | =payment-interest |
| Next balance | =balance-principal-extra |
Check one month against your real statement before trusting it. Servicer rounding differs by pennies. Source: CFPB guidance, November 2026.
Common build mistakes to avoid:
- Forgetting the PMT minus sign, which flips the sign.
- Using the yearly rate directly instead of rate divided by 12.
- Hard-coding the payment instead of referencing its cell.
- Forgetting the extra column in the next-balance formula.
What are the next steps to cut your interest cost?
Turn the tables above into a plan this week.
Build the sheet with your real balance, rate, and term. Pick an extra amount you can hold for years, not months.
Tell your servicer in writing to apply extras to principal. Verify the first statement shows the drop. Re-run the table yearly or after any refinance.
Windfalls belong in the plan too. Tax refunds and bonuses work best when they ride the same principal rail. Calibrate the extra amount after every big life change.
Verify current rates. Weekly survey numbers change. Check Freddie Mac's survey before any payment or refinance decision.
Photo: KimGo, Pixabay Content License, via Pixabay (https://pixabay.com/photos/calculator-pink-office-desk-4201244/)
Fazlur Rahman
