Debt Snowball Calculator

Total Debt only sums balances (line 30) — none of the rate or payment fields feed into it. Nudging Debt 1 Interest Rate, Debt 1 Min Payment, Debt 2 Interest Rate, Debt 2 Min Payment, or Extra Monthly Payment by 10% leaves Total Debt completely unchanged, because that output is a running count of dollars owed, not a projection of what you will pay.

At the calculator's own defaults, Debt 2 Balance — because it starts more than double the size of Debt 1 Balance ($12,000 versus $5,000), and Debt 3 Balance is left at its $0 default so it isn't part of the total at all (lines 26-28). Total Debt is a plain sum of the entered balances (line 30), so a proportional nudge to whichever balance already makes up the bigger share of that sum moves the total by more — Debt 2 Balance shifts it by roughly 14%, Debt 1 Balance by roughly 6%. That's not permanent, though: Debt 3 Balance shares the same $200,000 ceiling as the other two, so entering a real third debt easily makes it the biggest addend and the one that moves Total Debt the most instead.

Because Debt 1, at the default balances and rates, is both the smallest balance and the highest-rate debt at once. Snowball pays off the smallest balance first and Avalanche pays off the highest rate first (lines 34 and 70), so both strategies happen to start with Debt 1 — the payoff order, months, and total interest all come out identical until you set the rates or balances so the two orderings genuinely disagree.

No — Debt 3 Balance, Debt 3 Interest Rate, and Debt 3 Min Payment default to $0, and the engine only adds a debt to the working list once its balance is entered above zero (lines 26-28). Leaving Debt 3 Balance at its default is not the same as entering a $0 debt; it is treated as if that third debt does not exist at all.

The month-by-month simulation stops after 600 months — 50 years — even if the debts are not fully paid off by then (lines 42 and 77). With very large balances, very low extra payments, or a very high rate relative to the minimum payments, the calculator will report whatever total interest and payoff month accumulated up to that 600-month cap rather than flagging that payoff was never actually reached.