Free single-page tool. No sign-up, no data leaves your browser — every number is computed locally. It answers one question: this month, with this income, what do I pay — and what do I hold back?
1. Your income and essentials
2. Your debts
Minimum payment = the amount the lender requires each month. Leave unused rows at 0.
Debt
Balance ($)
APR (%)
Minimum ($/mo)
Press “Calculate this month”.
The three-tier rule this calculator follows
Tier 1 — buffer under 1 month of essentials: pay minimums only. Every spare dollar goes to the buffer first. A low month with no buffer is how people re-borrow to pay debt.
Tier 2 — buffer at 1 month: minimums + buffer top-up if needed, then all extra to one target debt (snowball or avalanche). High months pay down debt; low months fall back to minimums without touching the buffer.
Tier 3 — buffer at 3 months: throw everything above essentials + minimums at the target debt. The buffer is what lets you be aggressive without risking a missed payment.
Why the baseline month matters: a budget built on average income breaks in a low month. This calculator sizes everything to your lowest month, then treats a good month as a bonus to allocate — never as the plan.
What this does not do
It is a baseline planner, not financial advice. It does not know your loan terms, fees, penalty rates, or tax situation.
The debt-free estimate assumes every future month equals your lowest month — deliberately conservative. Real months with higher income will finish sooner.
It assumes fixed APRs and no new borrowing. Variable rates and new charges change the numbers.
Want the full spreadsheet?
I am building a full irregular-income debt payoff spreadsheet (Snowball / Avalanche + buffer waterfall, month-by-month plan, Google Sheets + Excel). If you want it when it is ready, request the full spreadsheet — one email, no list, no follow-up unless you ask.