💳 Loan Payoff Calculator
See how extra payments cut your loan short. Get payoff date, total interest saved, and the full month-by-month amortization schedule. Free, no signup.
What Loan Payoff Calculator Does
Every fixed-rate loan payment splits between interest on what you still owe and principal that reduces it. Because interest is charged on the remaining balance, that split shifts continuously — and any money you add on top of the scheduled payment goes entirely to principal, erasing all the future interest that balance would have generated.
That is why extra payments are disproportionately powerful. On a $25,000 loan at 6.5% over five years, adding $100 a month clears it 11 months early and saves $865 in interest — from $6,000 of extra payments that you get back as principal reduction rather than spend.
This calculator returns the scheduled payment, the accelerated payoff date, interest saved, and the full month-by-month amortization schedule. That last part matters: it is what lets you check that your servicer is actually applying extra money the way you intended.
How to Use Loan Payoff Calculator
- Enter your current loan balance amount
- Input the annual interest rate and original loan term in years
- Enter an optional extra monthly payment amount to test payoff acceleration
- Review total interest saved and your new earlier debt-free date
- Optionally view the month-by-month amortization schedule
Formula Used by Loan Payoff Calculator
Scheduled monthly payment
M = P × [ r(1 + r)^n ] ÷ [ (1 + r)^n − 1 ]
- P
- Loan principal — the current balance
- r
- Monthly rate: annual rate ÷ 12, as a decimal
- n
- Total scheduled payments
Worked example
$25,000 borrowed at 6.5% over 5 years.
- r = 0.065 ÷ 12 = 0.00541667, n = 60
- (1.00541667)^60 = 1.38282
- Numerator: 0.00541667 × 1.38282 = 0.0074903
- Denominator: 1.38282 − 1 = 0.38282
- M = 25,000 × (0.0074903 ÷ 0.38282)
Result: M = $489.15 per month; $4,349.22 of total interest over the full term.
The payment floor — below this the loan never amortizes
minimum_viable_payment > P × r
- P × r
- This month's interest charge. A payment at or below it leaves the balance flat or growing
Worked example
The same $25,000 balance at 6.5%.
- 25,000 × 0.00541667 = 135.42
Result: Any payment of $135.42 or less never touches principal. At a 24.99% credit card rate, a $5,000 balance has a floor of $104.13 — which is why a "2% of balance" minimum of $100 on that card would never pay it off.
What Extra Payments Buy — $25,000 at 6.5% over 5 Years
Scheduled payment is $489.15. Each row adds a constant amount on top, applied entirely to principal.
| Extra per month | Payoff time | Total interest | Interest saved | Months earlier |
|---|---|---|---|---|
| $0 | 5 yr 0 mo | $4,349.22 | — | — |
| $50 | 4 yr 6 mo | $3,867.77 | $481.45 | 6 |
| $100 | 4 yr 1 mo | $3,483.78 | $865.44 | 11 |
| $200 | 3 yr 5 mo | $2,910.10 | $1,439.13 | 19 |
| $300 | 2 yr 11 mo | $2,501.48 | $1,847.75 | 25 |
Rule of 78 — Why Some Loans Punish Early Payoff
A precomputed-interest method still legal for some short-term consumer loans in parts of the US. Interest is front-loaded by sum-of-digits weighting, so paying off early saves far less than it should. Example: a 12-month loan carrying $600 total interest.
| Method | Interest the lender keeps after 6 of 12 months | Share of total |
|---|---|---|
| Simple interest (normal amortization) | $300.00 | 50.0% |
| Rule of 78 (precomputed) | $438.46 | 73.1% |
How to Direct an Extra Payment
The single most common way borrowers lose the benefit of extra payments. Servicer defaults vary and are frequently unhelpful.
| What you want | What can happen instead | How to avoid it |
|---|---|---|
| Extra applied to principal | Held as a "future payment", so you skip next month and save nothing | Mark the payment "apply to principal"; use a separate transaction |
| Loan term shortened | Loan re-amortized to a lower payment over the same term | Ask explicitly; recasting is a different product from prepaying |
| No penalty for early payoff | A prepayment penalty is charged | Check the note before paying a lump sum |
How to Read Your Result
Early payments are worth more than late ones
A dollar of principal paid in month 1 avoids interest for the entire remaining term; the same dollar in the final year avoids almost none. On the $25,000 example, the first payment is $135.42 interest and $353.74 principal — but that ratio improves every month. If you can only make extra payments for a limited window, make them at the beginning.
Check the schedule against your statement
This is why the amortization table matters and why no competing calculator showing only a total is enough. Compare the projected balance after three months against your real statement. If they diverge, your extra payments are not being applied as principal — which is a phone call, not a maths problem.
Highest rate first, unless motivation is the constraint
With several debts, paying the highest interest rate first (avalanche) always costs less in total. Paying the smallest balance first (snowball) closes accounts sooner and some people sustain it better. The difference in money is usually modest; the difference in whether you finish is not. Choose honestly.
Prepaying is a guaranteed, risk-free return
Paying down a 6.5% loan is equivalent to a guaranteed 6.5% after-tax return with no market risk — which is more than most safe investments offer. The comparison flips only when the loan rate is very low or when you would be giving up an employer retirement match, which is an immediate 50–100% return.
Limitations & Accuracy Notes
- This models a simple-interest, fixed-rate, fully amortizing loan. Precomputed-interest loans (Rule of 78), variable rates, interest-only periods and balloon payments all behave differently.
- Fees are excluded: origination, late fees, and any prepayment penalty. Check your loan note for a prepayment clause before making a large lump-sum payment.
- It assumes every payment arrives on time and in full, and that extra amounts are applied to principal on receipt. Servicers do not always do this by default.
- Student loans are a special case. Federal loans have income-driven repayment and forgiveness programs where aggressive prepayment can be actively counterproductive — model those separately before accelerating.
- This is arithmetic, not financial advice, and it does not account for your tax position, emergency savings, or competing uses for the money.
Frequently Asked Questions
How does extra monthly payment reduce loan payoff time?
What is the formula for calculating loan payments?
Should I make extra monthly payments or one lump sum?
Can I use this for auto loans and student loans?
How much does an extra payment actually save?
Does my lender apply extra payments to principal automatically?
Is there a penalty for paying early?
Should I overpay the loan or invest instead?
Is my loan data stored?
References & Further Reading
- CFPB — How does my credit card company calculate the amount of interest I owe? — US regulator explanation of interest accrual on revolving balances
- eCFR — 12 CFR Part 1026 (Regulation Z, Truth in Lending) — Governs APR disclosure and prepayment terms in the US
- Federal Reserve — Consumer Credit (G.19) — Official average US rates for auto loans, personal loans and credit cards