Every fixed-rate loan payment is split into two parts: interest on what you still owe, and principal that actually reduces the balance. Early in a loan, most of each payment is interest, because the balance — and therefore the interest charged on it — is at its highest. Extra payments cut straight past that split.
Why Extra Payments Work
When you send more than your required monthly payment, the lender doesn't recalculate your regular bill — that extra amount is applied entirely to principal, with no interest taken out of it first. A smaller principal balance means the next month's interest charge (which is calculated on that balance) is also smaller. That saved interest compounds every single month for the rest of the loan, which is why even a modest, consistent extra payment can eliminate years of payments and tens of thousands of dollars in interest on a long-term loan like a mortgage.
This is fundamentally different from just paying your loan off faster with a lump sum at the end — the earlier the extra principal goes in, the more months of avoided interest it prevents, because it starts working on a larger remaining balance and for a longer remaining stretch of the loan.
How to Calculate Your Savings
- Open the Loan & Mortgage Calculator.
- Enter your loan amount, interest rate, and term as normal.
- Enter an amount in the "Extra Monthly Payment" field — even $50 or $100 makes a measurable difference on a long-term loan.
- Read the "Payoff Time," "Time Saved," and "Interest Saved" stats that appear, then open "Show Amortization Schedule" to see exactly how the extra payment shrinks the balance month by month compared to the standard schedule.
The Biweekly Payment Trick
A popular way to make "extra" payments without feeling the pinch of a bigger monthly bill is switching to biweekly payments — paying half your monthly payment every two weeks instead of the full amount once a month. Because there are 52 weeks in a year, this works out to 26 half-payments, which equals 13 full monthly payments a year instead of 12. That extra 13th payment is applied to principal, producing the same kind of savings as an explicit extra-payment strategy, just spread out differently. Not all lenders support true biweekly billing automatically, so check with your servicer — but you can approximate the same effect yourself by simply dividing your monthly payment by 12 and adding that amount as your "extra payment" each month.
When Extra Payments Might Not Be Worth It
Extra payments are a guaranteed return equal to your loan's interest rate, with no market risk — which is genuinely attractive, especially on higher-rate debt. But they're not automatically the best move for every dollar. If you're carrying higher-interest debt elsewhere (credit cards are a common example), paying that down first usually saves you more than prepaying a lower-rate loan. It's also worth keeping a cash emergency fund before aggressively prepaying a loan, since money put toward principal isn't easily accessible again if you need it unexpectedly. And if your loan's rate is unusually low, money invested elsewhere may reasonably be expected to outperform the interest you'd save — though unlike loan prepayment, that outcome isn't guaranteed.
FAQ
Does it matter when in the month I make the extra payment? It can, slightly. Interest accrues on your outstanding balance, so an extra payment made earlier in the month (or as its own separate payment right after your regular one posts) starts reducing the balance sooner, saving a small amount of extra interest compared to bundling it in at the very end of the billing cycle. The effect is minor compared to simply making the extra payment at all.
Is paying off a loan early always the best use of extra money? Not necessarily. It's a guaranteed, risk-free return equal to your loan's interest rate — great if that rate is high or if you simply value being debt-free. But if your rate is low and you have no emergency fund or higher-interest debt (like credit cards), building savings or paying off costlier debt first usually makes more financial sense than extra payments on a cheap loan.
What's the difference between an extra payment and refinancing? An extra payment keeps your original rate and term but shortens how long you'll actually be paying by shrinking the principal faster. Refinancing replaces the loan entirely with a new one, potentially at a different rate or term, and usually involves closing costs and a new approval process. Extra payments are simpler and reversible; refinancing can lower your rate but costs money upfront.
Can I stop making extra payments whenever I want? Yes, for most standard fixed-rate loans and mortgages without a prepayment penalty — extra payments aren't a binding commitment, you can add them in some months and skip others, and your minimum required payment stays the same either way. Check your specific loan terms for prepayment penalties, which are uncommon but do exist on some loans.