Extra payments · Lump sums · Real amortization
Enter your loan, then add extra monthly payments or one-time lump sums. Every change updates your payoff date, the interest you keep, and the full payment schedule instantly.
The ledger correction
Add an extra monthly payment or a lump sum above to see your payoff date move.
This $200 a month habit earns a guaranteed 6.5%. In Dec 2050 the loan dies and the whole $2,528.27 payment comes free. Race the same $200 against the market.
Have a target date in mind? The Debt-free by date calculator works backwards: pick your month and it finds the smallest extra payment that gets you there. Your numbers carry over.
All the math runs in your browser; nothing you enter is stored or sent anywhere. Last updated July 2026.
When half the principal is behind you.
Per day on the full balance. Every prepaid dollar stops its share.
Extra principal earns your rate, guaranteed, with no market risk.
Where you’ll stand if you sell or refinance then.
Each row reruns your loan with one flat monthly habit, next to the no-extras schedule. Click one to make it your plan.
| Extra / mo | Debt-free | Interest saved | Time saved | Make it the plan |
|---|
This table isolates the monthly habit. Lump sums and the bi-weekly setting are not counted in its rows, but they stay in your plan if you apply one.
Ordered by typical impact, biggest lever first. Your situation may reshuffle it. If you carry PMI, #2 can outrank everything. If your rate is already low, #1 drops off the list. Dollar figures use the example loan: $400,000 at 6.5% for 30 years, a $2,528 payment and $510,178 of lifetime interest. Run your own numbers above.
Extra payments earn exactly your rate. Refinancing changes the rate on every remaining dollar, which is why it’s the biggest single lever when it’s available. Rough test: can you cut your rate by about a point, and will you stay past the break-even on closing costs? If yes, price a refi before committing big lump sums. Then keep prepaying the new, cheaper loan to compound the win.
If you put less than 20% down, prepaying does double duty: on a conventional loan you can request PMI cancellation at 80% loan-to-value (it must drop automatically at 78%). Reaching that line even a couple of years sooner frees $100 to $250 a month on a loan this size. That is premium savings stacked on top of the interest savings, often the best per-dollar return anywhere in personal finance. Redirect the freed premium into principal and it compounds. (FHA loans usually carry MIP for life. There, refinancing is the removal path.)
The best habit is one you never re-decide. Rounding $2,528 up to a flat $2,700 sends an extra $172 to principal every month, finishes 4 yrs 11 mos sooner, and keeps $99,554 out of the interest column. Set it once in autopay and forget it. The gap between the two curves is money that stays yours.
Paying half your mortgage every two weeks means 26 half payments, which is thirteen full payments a year. On the example loan that finishes 5 yrs 10 mos early and keeps $116,342. You don’t need a program: add one-twelfth of your payment monthly (the bi-weekly toggle above models exactly this) or send one extra payment each December. Never pay a fee for this arithmetic. The bi-weekly calculator runs the true 26-payment calendar and prices the paid programs honestly.
Lump sums punch above their weight because they kill interest for every remaining month. A single $5,000 tax refund applied in year two saves $24,820. That is nearly five dollars back per dollar in. Make it a ritual and it rivals the big levers: $2,500 every year saves $111,040 and ends the loan 5 yrs 7 mos sooner. Add your expected refund, bonus, or vest as lump sums above.
The same $1,000 does wildly different work depending on when it arrives. Sent in year two, it erases $5,116 of future interest. Sent in year twenty, it erases $912. Early dollars retire principal that would have compounded against you for decades. Don’t wait until you can start big. Start small now.
Every tool inherits what you type here. Nothing to re-enter, nothing stored. Dollar figures are the example loan: $400,000 at 6.5% over 30 years.
Make your plan
Payoff calculatorYou are here
Add $200 a month and watch $111,892 of interest die. Lump sums and milestones too.
Amortization schedule
Every payment, split into interest and principal. $200 a month deletes 67 rows.
Debt-free by date
Pick the month; it finds the smallest extra that gets there. Twenty years costs $454.03 a month.
Before retirement
Paid off at 65 instead of 71 costs $221.89 a month. Priced in birthdays, not dates.
Weigh your options
Prepay vs invest
The market has to beat your mortgage rate after tax. Both roads run to the cent.
Bi-weekly payments
Half-payments every two weeks finish 5 years 10 months sooner. The paid programs get priced too.
Recast
A $50,000 lump can cut the payment $319.60 a month. The lower payment’s price: $137,661.
Refinance
The advertised break-even says 25 payments. The honest ledger says 20. You see both.
Today’s numbers
Payoff amount
The statement says $395,529.10. The check that clears the loan says $396,515.26.
PMI removal
Asking at 80% instead of waiting for 78% keeps $2,805. Both dates, dated.
No. Your required payment stays the same. Extra principal shortens the loan and cuts total interest instead. If you want a lower required payment after a big lump sum, that’s what a recast is for (see below).
More than most people guess. On the example $400,000 loan at 6.5%, one extra payment a year (or its bi-weekly equivalent) saves about $116,000 in interest and ends the loan 5 years 10 months early. Flip the bi-weekly toggle above to see the number for your own loan.
Use the “principal-only” option in your servicer’s payment portal, or note it explicitly on a mailed check. Then confirm on the next statement that the balance dropped by the full amount rather than your next due date moving forward.
On conventional loans you can request cancellation once the balance reaches 80% of the home’s original value, and the servicer must remove it automatically at 78%. Extra principal pulls both dates closer, and some servicers will also cancel based on a new appraisal if the home has appreciated. FHA mortgage insurance usually lasts the life of the loan, so refinancing is the removal path there.
You can replicate them for free. A bi-weekly schedule is just one extra monthly payment per year in disguise. Add 1/12 of your payment each month or send one extra payment annually and you get the identical result without fees. The bi-weekly calculator puts the schemes and their fees side by side.
Prepaying earns a guaranteed return equal to your rate (a little less if you deduct mortgage interest on your taxes). Compare that honestly to what you’d earn elsewhere after taxes and risk. Fund retirement matches and an emergency fund first. And remember that “guaranteed and sleep-well” is worth something too.
After a large principal payment, many servicers will re-amortize your remaining balance over the remaining term for a small fee. Your rate and payoff date stay put, but the required monthly payment drops. Not all loans qualify, so ask your servicer.
With the standard amortization formula: payment = P × r(1+r)n / ((1+r)n − 1), where P is the principal, r the monthly rate (APR ÷ 12), and n the number of months. Each month, interest accrues on the remaining balance (balance × r); the rest of the payment, plus anything extra you send, retires principal. Every figure on this page comes from running that loop payment by payment.
The payoff math is principal and interest only. Add property tax, insurance, HOA, and PMI under advanced options to see your estimated total monthly cost. Those amounts are for budgeting only and do not affect the payoff date.