Savings vs Debt Repayment Calculator
Compare two uses of the same monthly cash by savings minus remaining debt at a common deadline.
A QUICK WALKTHROUGH
How to use this tool
- Enter your debt, fixed minimum payment, extra cash and currency.
- Choose each annual rate basis independently and enter a horizon in whole months.
- Compare both paths at the deadline and copy or download the full monthly report.
Monthly model
Effective annual: r = expm1(log1p(annual% / 100) / 12). Nominal annual: r = annual% / 100 / 12. Each month interest = opening debt × debt r; savings growth = opening savings × savings r. Payments and deposits occur at month end. Net = savings − debt; difference = repay-first net − save-instead net.
Timing and scope
Both paths use minimum + extra every month and start with zero savings. Repay first sends all cash to debt; save instead pays only the fixed minimum. Each saves every unused amount in the same month, including the payoff month. No tax, fees, changing rates, daily interest or liquidity value is modelled. An entered return is an assumption. Compare net positions at the same date, not whole-life interest against growth over a different period.
Local report
Inputs remain in your browser. The TXT report includes the successful input snapshot, rate bases, units, timing, deadline totals and every month for both paths.
GOOD TO KNOW
Common questions
What if the debt is not repaid by the deadline?
The remaining debt is shown and deducted from savings. No later payoff or whole-life interest is inferred.