Debt Payment Plan Calculator
Build a debt payoff plan with monthly payments. Instantly see your debt-free date, total interest, payoff timeline, and how extra payments accelerate results.
How It Works
Enter your loan or debt balance, annual interest rate, and the monthly payment you can afford. The calculator instantly shows your exact debt-free date, total interest you'll pay, and how much you save by adding extra payments each month. Results update in real time.
Formula
t = -log(1 - r*P / M) / log(1 + r)
Where: t = number of months to pay off the debt | P = starting principal (loan balance) | M = fixed monthly payment | r = monthly interest rate = Annual Rate (%) / 12 / 100. M must be greater than r*P or the debt will never be paid off.
Worked Example
Paying off $15,000 in personal loan debt
- Debt Amount: $15,000
- Annual Interest Rate: 18% APR
- Monthly Payment: $350
- Monthly interest rate (r): 18% / 12 = 1.5% = 0.015
- t = -log(1 - 0.015 * 15,000 / 350) / log(1.015) = approx 57 months
- Result: Debt-free in 57 months (4 years 9 months). Total interest paid: $4,916.
- With $100 extra/month ($450 total): 42 months, $3,341 in interest — saving $1,575 and 15 months.
Common Mistakes
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Only paying the minimum required amount
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Minimum payments are designed to maximize the bank's profit. Always pay more than the minimum to reduce principal faster and dramatically cut the total interest you pay.
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Ignoring interest rates when prioritizing debt
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Use the Avalanche method: focus extra payments on the debt with the highest interest rate first to save the most money over time.
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Using the original loan amount instead of the current balance
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If you've already been making payments, use the remaining balance — not what you originally borrowed. Check your last statement for the 'Current Balance' figure.
Frequently Asked Questions
Related Guide & Instructions
2026-07-08
Debt Snowball vs. Debt Avalanche: Which Plan Gets You Debt-Free Faster?
Compare the two most popular debt payoff strategies and learn how to build an accelerated repayment schedule.
Read full guide →Related Calculators
DisclaimerThe results provided by this calculator are estimates and for informational purposes only. They do not constitute financial, legal, or professional advice. Please consult with a qualified professional for your specific needs.