Loan Payoff Calculator with Extra Payments
See how extra monthly payments shorten a loan and cut total interest — compare payoff time and interest with and without overpayment.
Result
- Base monthly payment (P&I)$1,199.10
- New payment with extra$1,399.10/mo
- Original payoff360 months (30.0 yr)
- New payoff252 months (21.0 yr)
- Time saved108 months (9.0 yr)
- Interest without extra$231,676.38
- Interest with extra$151,875.87
- Total interest saved$79,800.51
Step-by-step
- Base payment on $200,000.00 at 6% over 30 years = $1,199.10/month.
- Adding $200.00/month sends $1,399.10 total, all extra going to principal.
- Loan pays off in 252 months instead of 360 — 108 months sooner, saving $79,800.51 in interest.
How to use this calculator
- Enter the loan amount, annual rate, and original term.
- Enter the extra amount you plan to pay each month.
- Read the new payoff time and the total interest saved.
- Compare original versus accelerated payoff in the breakdown.
About this calculator
Making extra payments on a loan is one of the most reliable ways to save money, because every additional dollar goes straight to principal — and reducing the principal cuts the interest charged on every remaining month. This calculator amortizes your loan twice: once with the standard payment and once with your extra monthly amount added. It then shows how many months and how much interest the extra payments save. The effect is often dramatic on long mortgages: even a modest extra amount each month can shave years off the term and tens of thousands of dollars off the total interest, because interest savings compound over the life of the loan. Before relying on this, confirm your lender applies extra payments to principal (not future payments) and charges no prepayment penalty.
How it works — the formula
Base payment = L · r(1+r)ⁿ / ((1+r)ⁿ − 1)
Each month: interest = balance × r; principal = payment − interest
Extra payment adds directly to principal, ending the loan early.The loan is amortized month by month; adding to the payment accelerates principal reduction, compounding the interest savings until the balance reaches zero.
Worked examples
- Inputs:
- loan=200000, rate=6, term=30, extra=200
- Output:
- payoff ~21 yr, saves ~$80k interest
- Inputs:
- loan=200000, rate=6, term=30, extra=0
- Output:
- 360 months, ~$231,676 interest
- Inputs:
- loan=30000, rate=5, term=5, extra=100
- Output:
- pays off ~9 months early
Limitations
- Assumes a fixed rate and that all extra goes to principal.
- Ignores taxes, insurance, escrow, and prepayment penalties.
- Monthly compounding; biweekly schedules differ slightly.
Confirm prepayment terms with your lender; not financial advice.