Debt Payoff Calculator
Calculate payoff timeline, interest costs, and acceleration savings with additional monthly payments.
Last verified: September 2026Inputs & Parameters
Calculation Results
Paying an extra $50/month reduces debt payoff from 31 to 24 months, saving $248.50 in interest.
Accelerating Debt Payoff and Interest Savings
Credit card balances and high-interest revolving credit compound against borrowers monthly. Paying more than the minimum required monthly payment accelerates principal reduction, drastically curtailing overall interest expenditure and shortening the debt freedom timeline.
Core Mathematical Formulas
- Payoff Duration (Months):
n = -ln(1 - (r × B) / PMT) / ln(1 + r) - Total Interest Paid:
Interest = (PMT × n) - Initial Balance - Interest Savings:
Savings = Interest(Standard) - Interest(Accelerated)
Worked Example
A credit card balance of $8,000.00 at 19.99% APR with a baseline payment of $200.00/month vs an accelerated payment of $350.00/month:
1. Standard Payoff: 66 months (5.5 yrs) with $5,198.81 in total interest.
2. Accelerated Payoff (+$150/mo): 29 months (2.4 yrs) with $2,143.92 in interest.
3. Net Savings: 37 months shaved off and $3,054.89 interest saved.
Assumptions & Limitations
Requires that the monthly payment strictly exceeds monthly accrued interest (PMT > Balance × Monthly Rate), otherwise the balance grows indefinitely (negative amortization). Assumes no additional card charges during the payoff period.