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Debt Planner

Methodology

The calculator uses deterministic monthly payoff modeling with simplified APR divided by 12.

Monthly interest

For the MVP, monthly interest is estimated as current balance multiplied by APR divided by 12. Real lenders may use daily periodic rates, fees, grace periods, and different payment allocation rules.

Payment allocation

Every active debt receives its minimum payment first. Remaining monthly budget is directed to the priority debt. When a debt is paid off, its freed payment is redirected to the next active priority debt.

Strategy ordering

Debt Avalanche prioritizes highest APR first. Debt Snowball prioritizes lowest balance first. Ties are resolved deterministically using secondary fields so repeated calculations return the same result.