Extra Monthly Payments: How Much Sooner You Pay Off and What You Save

A $300,000 loan at 6.5% over 30 years costs $1,896.20 a month and $382,636.71 in interest if you simply follow the schedule. Add $200 to every payment and the loan is gone after 277 months instead of 360 — 6 years and 11 months sooner — with $103,450.19 less interest.

Over those 277 months you put in $55,200 of extra money. Each extra dollar saves close to two dollars of interest, which makes extra payments one of the simplest ways to pay a loan off early. The size of that saving depends on three things you control: how much you add, when you start, and whether your contract charges a fee for paying early.

What should you compare?

When you test an extra payment, look at these together:

• New payoff — how many months the loan now runs, and how many months earlier it ends.
• Interest saved — the difference between the original schedule's interest and the new one's.
• Extra paid — the total cash you put in above the schedule. It is not a cost, since it all goes to principal, but it is money you can't use for anything else.
• Prepayment fees — some contracts charge for paying early. A minimum fee on each prepayment can take a surprisingly large bite out of small monthly extras.

Extra monthly payments at a glance

All rows use the same $300,000 loan at 6.5% for 360 months, with equal payments and the Shorten term option. The extra-paid column is our own total, not a figure the app shows.

The first $100 does the most work per dollar: about $1.96 of interest saved for every extra dollar. At $200 it is about $1.87, and at $500 about $1.72. Bigger extras still save more in total; they just shorten the loan so much that each dollar has less time to work.

1. Why a small extra payment goes so far

Best for: understanding where the savings actually come from.

In an equal-payment loan, the early payments are mostly interest, as any amortization schedule shows. In the first month of this loan:

Interest       = 300,000 × 6.5% ÷ 12 = $1,625.00
Principal      = 1,896.20 − 1,625.00  = $271.20
With $200 extra: principal = 271.20 + 200 = $471.20

The extra payment goes entirely to principal, so it almost doubles the amount of debt you clear that month. Interest is charged on the remaining balance, so every dollar you clear early stops costing interest for the rest of the loan.

The effect looks small at first. After one year of $200 extras, the balance is $294,174.07 instead of $296,646.88, and you have paid $19,328.47 of interest instead of $19,401.28. But the gap widens every month, and by the end it adds up to 83 fewer payments.

2. Start early: the same $200 is worth less later

Best for: deciding whether to start now or wait until money is less tight.

Timing matters as much as amount. Compare the same $200 a month started at two points:

Waiting five years costs you about $36,500 of the savings, even though you would put in only $7,400 less extra money. The earliest months of a loan carry the most interest, so money put in then does the most good.

3. Let the extra grow with your income

Best for: borrowers who expect their income to rise.

A fixed $200 may feel large today and small in ten years. The Increase extra by % each year field raises the extra amount once a year, starting in the 13th month. At 5%, you add $200 a month in year 1, $210.00 in year 2, $220.50 in year 3, and so on.

That modest step-up makes a real difference: the loan is paid off after 249 months, 111 months early, with $126,793.13 of interest saved — about $23,300 more than a flat $200.

4. Check prepayment fees before you commit

Best for: loans whose contract charges for paying early.

Turn on the Prepayment fee switch in the simulator and three fields appear: Prepayment fee (% of prepaid amount), Minimum fee per payment and Fee-free from period. The app charges the fee in every month you prepay: the percentage of that month's extra, but never less than the minimum, and nothing from the fee-free period onward.

Here is the $200-a-month plan under four fee rules:

1% of $200 is only $2, so with a $25 minimum you pay $25 on every one of the 276 extra payments. A fee-free period after three years cuts that to 36 payments, or $900.

If you entered a Prepayment fee (%) under Fees & insurance on the main calculator, the simulator opens with the fee switch already on and that percentage filled in.

5. How to simulate extra monthly payments in Loan Calculator

Best for: testing your own numbers in under a minute.

1. Calculate your loan on the main screen, then tap Prepayment simulator under the results. You can also open it from the Tools tab. The amount, rate, term and method of your last calculated loan are copied into Loan details.
2. Check the Interest method (Equal payment or Equal principal) and leave After prepaying on Shorten term.
3. Enter your Extra amount every month. Add a percentage in Increase extra by % each year if you plan to raise it.
4. If your contract charges for prepaying, turn on Prepayment fee and fill in the rule. Leave the minimum and fee-free fields blank if your contract has neither.
5. Tap Simulate. New payoff shows, for example, "277 months (83 months earlier)", followed by Interest saved. With fees on, you also see Prepayment fee and Net saving.
6. Tap New schedule by year to see what you pay, the interest and the remaining balance for each year.

The prepayment simulator is a Pro tool. Without Pro, you can unlock it for 24 hours with 3 credits.

Which extra payment plan should you choose?

FAQ

Should I pay extra every month or save up for a lump sum?

Without fees, money paid earlier saves more interest, so monthly extras usually win. With a minimum fee per prepayment, fewer and larger payments can come out ahead. Run both in the simulator and compare Net saving.

What happens if I choose Lower payment with monthly extras?

The loan keeps its original end date and the scheduled payment is recalculated after each extra. With $200 a month, the app shows "Month 2: scheduled payment $1,894.94 instead of $1,896.20 (excluding extra payments)", and the interest saved is $42,484.92 instead of $103,450.19. You get a slowly shrinking bill instead of an earlier payoff.

Can I model extra payments that start later?

Yes. The extra amount starts in the first month of the loan details, so enter your current balance and the months left instead of the original loan.

Will my lender's numbers match the app exactly?

They should be close, but not always to the cent. The app uses the annual rate ÷ 12 for monthly interest; lenders may count actual days, round differently or apply fee rules the simulator does not model. Treat the results as estimates.

Does the app work offline?

Yes. The simulator runs entirely on your device and works with no internet connection. Your loan figures stay on your phone.