Debt Payoff Calculator
Months to clear a debt and total interest from balance, rate and payment.
How it works
n = −ln(1 − r·B ÷ payment) ÷ ln(1+r), r = annual÷12
For high-rate revolving debt, if the payment is below the monthly interest it never clears (shown as "—").
Worked example
Balance 50,000 at 18% (1.5%/month), paying 2,000/month:
n = −ln(1 − 0.015×50000/2000) ÷ ln(1.015) ≈ 31.6 — about 32 months.
Total paid ≈ 64,000, of which ≈ 14,000 is interest — nearly 28% of the principal.
Notes and limitations
High-rate debt outranks investing: a guaranteed 18% return is hard to find in markets. Negotiating a lower rate or consolidating usually beats cutting small expenses.