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Our Methodology

Use this page to understand the calculation assumptions, check worked examples and find our sources.

How we calculate a payoff plan

The main and single-card calculators in all available language versions share one monthly model. All amounts are in US dollars. This is an estimate: your lender may calculate daily interest and apply different terms.

For a card, enter the APR for that balance. For a loan, use the contractual rate applied to the balance if it differs from the APR that includes fees. This model excludes those fees. CFPB: interest and APR.

  1. Take each opening monthly balance. Calculate interest as balance × annual APR / 1,200, then round to cents; exact half cents round up. We use integer cents and APR with two decimal places to avoid binary rounding errors. For example, $600 at 2.01% produces $1.01 of first-month interest.
  2. Apply the fixed minimum payments entered. A debt payment never exceeds its balance plus that month's interest.
  3. Allocate the remaining budget by method. Snowball targets the smallest opening balance; avalanche targets the highest APR. Reassess that order each month. Ties use APR for snowball and balance for avalanche, then entry order.
  4. Keep the initial budget constant: minimums on debts with a balance plus the extra payment. A freed payment can go to the next debt in the same month.

Rates and minimums stay fixed. The model excludes new charges, fees, promotional rates, rate changes and minimums that decline as a percentage of balance. The first estimated payment is next month. Amounts and APR admit at most two decimal places. If a balance or cumulative amount exceeds the model’s numeric limit, it stops without reporting payoff. Calculations stop at payoff or 1,200 months; reaching that limit is not reported as a successful payoff.

Reproducible examples

A blank numeric field is incomplete. Enter 0 explicitly where appropriate. We support up to 10 debts, APRs from 0% to 100%, and amounts up to $1,000,000,000 per field.

Calculating does not send or automatically save your entries. The main calculator lets you save a copy in this browser only if you choose; see our privacy policy. Compare my payoff plans.

How the optional target-period calculation works

The main calculator can search for a monthly budget for a target of 1 to 1,200 monthly payments. Target budget is calculated using the avalanche method. The search uses the same balances, annual rates, fixed minimums, rounding and payment rules described above; it does not use a separate payoff formula.

Before returning a proposal, the calculator checks that its avalanche schedule finishes within the chosen period. It is a checked estimate, not a guarantee that no smaller budget could work. The tool does not calculate a target budget using snowball. If the search cannot find a checked plan within its limits, it reports that outcome without claiming that the financial goal is impossible.

The budget includes the entered fixed minimums for debts with a positive balance plus one shared extra payment. Those minimums remain fixed. If they already clear the debts before the target, the result can finish earlier; the search does not reduce them to use the whole period. The first estimated payment is next month, counted as payment 1. This is not an exact payment date or a lender payoff quote. Rates, fees, new charges and actual payment timing can change the outcome.

Finding a proposal leaves the current extra payment unchanged. Only “Apply budget and compare” replaces that extra with the calculated extra and runs the existing comparison. Both methods then use the same total budget, but snowball can finish in a different month. Check each method’s own result before selecting its schedule to view, download or print. The schedule selector does not recalculate the budget using snowball.

For example, one $1,000 debt at 0% with a $50 fixed minimum and $25 current extra has a $75 monthly budget and takes 14 payments. A target of 10 payments returns a $100 budget, including $50 extra: $25 more than the current budget. Searching leaves the form unchanged. Applying that proposal sets the extra to $50, after which both methods take 10 payments with no interest. Follow the step-by-step target example to reproduce it.

Data sources

We use primary sources for financial and legal facts, including:

Review and scope

On September 6, 2026, we updated the shared debt payoff model and its examples. Checks cover partial final payments, 0% interest, payment rollover and calculation limits. This review does not certify every legal, tax or financial article on the site.

Editorial independence

The calculators do not ask you to apply for a financial product. Read our affiliate disclosure for information about commercial links.

Corrections policy

To report a source, translation or calculation issue, use our editorial contact page. Include the page and a reproducible example where possible. We assess the report before deciding on a correction. A note for a significant correction should identify the affected content and what changed; it should not imply that unrelated material has been reviewed.

What we don't claim

We don't claim to provide personalized financial advice. We don't claim to know your specific situation. We don't claim that any single strategy works for everyone. We don't claim that following our calculators will eliminate financial stress. The examples show how to check the model against its stated assumptions. Report discrepancies through the contact above.

Calculation methodology updated: September 7, 2026.

One-time payments and declining minimums

A one-time payment in the main calculator increases the budget only in the selected month. Month 1 is the next estimated month. Monthly interest is charged first, then debts are paid with that month’s budget. Results identify the amount used and any amount not applied if the debts are paid off earlier. The schedule and its CSV include that payment exactly once.

The target-period budget search excludes the one-time payment. Applying its budget preserves the one-time amount and month and resimulates both methods with the complete inputs. The final schedule may therefore finish earlier than the target estimate.

In the declining-minimum comparison, choose a percentage of the opening monthly balance or a percentage of the opening balance plus that month’s interest, with a dollar floor. Components round to cents, with exact half cents rounding up. Payments never exceed the amount owed. Extra is added to each month’s minimum; the other option holds your chosen payment fixed. Both first payments are shown so you can see whether the initial cash commitment differs. These are editable assumptions: check your card agreement. Fees, new purchases and daily interest are excluded.

Available cash and offers

The budget and calendar separates monthly take-home income and expenses from dated movements. The protected reserve reduces available funds without becoming another bill. The calendar treats bills as preceding income on the same day to reveal a possible timing gap; it does not predict bank processing order. Every 14 days is different from two dates per month.

The consolidation comparison matches net cash to the balances being replaced and includes the fee according to its treatment. It compares complete nominal costs only when the existing plan repays in full. The balance-transfer comparison applies one rate during the promotion and another afterward; it does not model retroactive deferred interest. Each tool states its specific assumptions and limits.

Hardship worksheets and an existing mortgage

The DMP worksheet uses the same balances in both scenarios and holds each account payment fixed, without rolling freed payments to other accounts. Agency fees remain outside principal. Total costs are compared only when both scenarios finish. The medical worksheet models the written proposal entered: a difference from the original bill is not debt forgiveness or approved assistance.

The mortgage uses the current balance, fixed rate and principal-and-interest payment from a statement. Property taxes, insurance, PMI, HOA and other housing costs are separate; they do not repay principal. Extra payments preserve the required payment, without recast, automatic PMI cancellation or variable rates. Plans have a 1,200-month limit and stop if a payment does not reduce the balance, showing a partial status.

Letters, logs and the tax folder prepare documents for user review. They do not send correspondence, calculate legal deadlines or determine tax exclusions. The EN/ES quiz shares one rule source; it prioritizes court notices and suggests educational resources.

Savings, investment scenarios and reproducible examples

The compound-interest tool and savings-goal tool use an effective annual return converted to a monthly rate. They apply growth or loss, deduct the entered proportional fee, then add the end-of-month contribution. Growth and fees round to cents each month. The goal tool finds the smallest monthly contribution in cents that meets its target at the chosen horizon. Inflation adjusts purchasing power; it does not create additional money. Each tool explains its own fee convention and limits for 1–600 months.

The debt-versus-investment comparison keeps the same starting balances, monthly budget and horizon in both paths. It invests money freed by the last debt payment and subtracts any debt still owed at the horizon. Debt uses a nominal annual rate divided by 12; investment uses an effective annual return. Equal entered percentages do not mean equal monthly rates. Constant-return scenarios are not forecasts, probabilities or an after-tax recommendation.

The reproducible debt-payoff study contains four fictional portfolios, three extra-payment amounts and two methods: 24 schedules and 12 paired comparisons. Its inputs, complete results and reproduction script are public. These selected examples explain calculation mechanisms; they are not a survey or a measure of real users’ results.

Difficult months and actual balance reviews

The difficult-month worksheet uses the existing cash-flow model to order the income and bills you enter. It highlights dates and reserve shortfalls, not a universal order for paying or skipping bills. Check the consequences and available arrangements with the relevant provider.

The monthly review compares balances from your statements with the payments, new charges and interest or fees you enter. It displays any unexplained difference; it does not infer why a balance changed. A projected balance is optional and shown separately from the actual balance. Missing terms in an offer remain unknown until you verify them in writing.

Interpretation, uncertainty and corrections

Tool assumptions are conventions for the displayed scenario, not a statement that your lender uses the same method. A missing rate, fee or term remains unknown until you verify it. A partial schedule, a model limit or an input error must not be read as successful payoff or proof that a plan is impossible.

All available translations of a tool use its shared calculation engine. Simplified and Traditional Chinese are written versions, not separate legal jurisdictions or spoken-language service commitments. A tested calculation does not validate legal eligibility, creditor acceptance or a future investment return. Refer to the page-specific assumptions and primary source dates.

If an estimate differs from a statement, check dates, daily versus monthly interest, fees and the rate entered before changing a payment. Report a reproducible discrepancy at xaviercahe@gmail.com. Actual statements, the applicable agreement and current official rules require their own review.