What it is and when to use it
The debt snowball is a payoff strategy in which you make minimum payments on every debt, then send every spare dollar to the smallest balance. When that debt is gone, its payment rolls into the next smallest, so the amount aimed at each debt grows like a rolling snowball. The method is popular because early wins arrive quickly and keep people motivated.
This calculator estimates the payoff effect of your extra monthly payment. Enter the extra amount you can add, the average interest rate across your debts and the total balance. It reports the assumed minimum payment, your projected debt-free date, total interest, and how much interest and time you save compared with paying only the minimum. Use it to test how much an extra $50 or $200 a month changes the timeline.
The formula and how it works
The calculator models the debts as a single loan with a fixed monthly payment:
- r = annual rate / 100 / 12, the monthly interest rate.
- Minimum payment = max($25, 2% x balance).
- Payment P = minimum + extra payment.
- Months n = -ln(1 - r x B / P) / ln(1 + r), where B is the balance. At 0 percent interest this reduces to B / P.
- Total interest = P x n - B. Savings compare this with the same calculation using only the minimum payment.
The projected date is today plus the number of months rounded up. If P is not larger than r x B, the debt never pays down and the calculator says so.
Worked example
Take a total balance of $15,000 at 18.9 percent with $200 extra per month. Monthly rate r = 0.189 / 12 = 0.01575. The minimum is max(25, 0.02 x 15,000) = $300, so the total payment is $500.
Months = -ln(1 - 0.01575 x 15,000 / 500) / ln(1.01575) = -ln(0.5275) / 0.015627, about 40.9, which rounds up to 41 months. Interest is 500 x 40.93 - 15,000 = $5,464.45. With the minimum only, the payoff takes about 99.1 months and costs about $14,732.92 in interest. The difference is $9,268.47 saved and roughly 58 months sooner, matching what the calculator prints. The debt-free month shown depends on today's date.
Common mistakes and how to interpret the result
- Ignoring the rate: on high-interest cards a few points of APR change the result more than a small increase in the extra payment.
- Forgetting new charges: adding to balances while paying them down resets the timeline, and the calculator assumes no new debt.
- Counting a tiny extra payment as progress: if the payment barely exceeds monthly interest, payoff is very slow.
- Using an average rate for very different debts: the pooled estimate hides that a high-rate card might justify going first, so treat the output as a planning estimate.
Frequently Asked Questions
Does this calculator order my debts smallest to largest?
What minimum payment does it assume?
Why does the result say my extra payment is too small?
Is snowball better than avalanche?
Related calculators
- Debt Avalanche Calculator
- Debt Snowball Acceleration Calculator
- Credit Card Payoff Calculator
- Debt-to-Income Calculator
Common Tip Percentages
| Service | Typical Tip Range | Notes |
|---|---|---|
| Restaurant (sit-down) | 15–20% | 20%+ for exceptional service |
| Food delivery | 10–20% | Consider extra for long distances |
| Taxi / rideshare | 10–20% | More for assistance with luggage |
| Hotel housekeeping | $2–5/night | Leave daily, not just at checkout |
| Barber / hair salon | 15–20% | On pre-discount total |
| Pizza delivery | 10–15% or $3–5 minimum | Higher in bad weather |
General Household Budget Ratios (50/30/20 Rule)
| Category | % of Net Income | Examples |
|---|---|---|
| Needs | 50% | Rent, groceries, utilities, insurance |
| Wants | 30% | Dining out, entertainment, hobbies |
| Savings / Debt | 20% | Emergency fund, retirement, extra payments |
Common Measurement Conversions for Everyday Use
| Quantity | US / Imperial | Metric Equivalent |
|---|---|---|
| 1 cup | 8 fl oz | 237 mL |
| 1 pint | 16 fl oz | 473 mL |
| 1 quart | 32 fl oz | 946 mL |
| 1 gallon | 128 fl oz | 3.785 L |
| 1 lb | 16 oz | 453.6 g |
| 1 ft | 12 in | 30.48 cm |