Debt Payoff Formula Explained
The math behind the Debt Payoff Calculator: the equation, the variables, and the assumptions it makes.
By Onias Derilus, Mortgage Capital · NMLS# 1859012 · Last Updated: June 2026
It shows how long it takes to pay off your debts and how much interest you save by adding extra payments or using the avalanche or snowball method.
The Formula
Months to payoff and total interest depend on payment, balance, and rate
The avalanche method targets the highest interest rate first, which minimizes total interest. The snowball method targets the smallest balance first, which delivers quick wins that help motivation.
Every extra dollar shortens the timeline and cuts interest, with the largest effect on high-rate balances. The calculator quantifies both the time and the money each strategy saves.
Turn Your Debt Payoff Estimate Into a Real Pre-Approval
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Rates are illustrative only. APR and payments vary by credit score, loan amount, and market conditions. Subject to credit approval. Not a commitment to lend. NMLS# 1859012. Equal Housing Lender.