Debt Payoff Calculator

The Debt Payoff Calculator computes debt payoff from the relation months = minus log(1 minus (monthly rate x balance) over payment) divided by log(1 plus monthly rate). It takes 3 inputs (current balance in USD, annual interest rate in %, monthly payment in USD) and returns the debt payoff. These calculators are for people working through everyday money questions: judging whether a price or an offer is worth taking, working out who owes what on a shared bill or cost, and comparing what one borrowing option costs against another, so the number feeds a concrete decision about spending, splitting or borrowing. Enter your values below and the result updates instantly, and you can share a permalink that pre-fills the exact calculation. Enter every amount in the same currency, and where a calculator uses a rate or a period, keep those on one consistent basis (monthly figures with monthly, annual with annual); be clear about whether each amount is before or after tax and fees, and round only the final figure rather than rounding at each step. For example, with current balance = 5000 USD, annual interest rate = 12 %, monthly payment = 200 USD, the debt payoff works out to 28.91181, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. The method is the standard form documented by CalculatorHub methodology, and the figure above each result carries the date it was last verified. The result is arithmetic on the amounts you type in, so what you actually pay or receive can differ once a seller's or lender's own rounding, fees, minimum charges and contract terms apply; use it as a working figure for your own planning and check it against the offer, statement or agreement in front of you.

With Current balance = 5000 USD, Annual interest rate = 12 %, Monthly payment = 200 USD, the result is 28.91181.

Formula: months = minus log(1 minus (monthly rate x balance) over payment) divided by log(1 plus monthly rate). Source: CalculatorHub methodology, as at 2026-06-23.

Debt Payoff28.91181

Applies to: any numeric inputs. Method source: CalculatorHub methodology, checked 2026-06-23.

The formula

months = minus log(1 minus (monthly rate x balance) over payment) divided by log(1 plus monthly rate)

Worked example

With Current balance = 5000 USD, Annual interest rate = 12 %, Monthly payment = 200 USD:

  1. Monthly rate = 12 / 100 / 12 = 0.01
  2. Apply the amortisation payoff formula with balance 5000 and payment 200
  3. Months to pay off = 28.9118097374808
  4. Debt Payoff = 28.91181

This worked example is one of the automated golden-value tests this calculator must pass before it can publish.

What this assumes

  • Inputs are real numbers in the units shown.
  • The result is the exact value of months = minus log(1 minus (monthly rate x balance) over payment) divided by log(1 plus monthly rate); general information, not professional advice.

Frequently asked questions

What formula does this use?

months = minus log(1 minus (monthly rate x balance) over payment) divided by log(1 plus monthly rate), the standard form documented by CalculatorHub methodology.

Does the result ever change over time?

No. This is a pure formula with no external rate, so the same inputs always give the same result.

Official sources and verification

Reviewed by the CalculatorHub team, edited by James Graham, 2026-06-23. See our methodology. General information, not professional advice.