Repay debt or invest?
This calculator simulates both scenarios month by month to show which approach grows your net worth faster. Get a clear recommendation and the break-even return where investing beats overpayments.
Adjust debt parameters, expected returns and horizon. Results update instantly, so you can see how a single change – shortening the term or increasing returns – affects your final net worth.
- Break-even return
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- Net worth – repay
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- Net worth – invest
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- When cash is freed
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Fill in the form to see the return where investing starts to win.
Portfolio value if you focus entirely on debt.
Portfolio value when you direct the surplus into investments.
See how many years it takes until the instalment turns into 100% investing.
Build your scenario
Enter debt details, expected return and investing horizon. The algorithm compares two strategies: aggressive overpayment versus investing the surplus while paying the minimum instalment. The result is a recommendation plus the net-worth gap.
- The overpayment path assumes every repaid złoty later works fully in investments.
- The investing path grows at your chosen return while the debt is serviced with the required instalment.
- We compare net worth (assets minus debt) to highlight the real financial benefit.
The left card shows assets after clearing the debt, the right card – after investing regularly. The larger the gap, the stronger the winning strategy. If you see validation errors, click the relevant field for guidance.
⚡ Lightning decision: debt or investing?
Calculator results
Fill in the form on the left to see the recommendation.
How to read the chart?
Net worth combines rising investments and shrinking (or rising) debt. Line crossings mark when one strategy grows wealth faster than the other. Even if investing wins early on, you will see when debt costs catch up.
A sudden lift of the overpayment line means the mortgage is paid off and the full instalment switches to investing.
- Coloured areas under the lines show how quickly net worth accumulates – the bigger the area, the faster the growth.
- Green vertical bands mark strategy switches. They reveal whether investing needs a longer horizon to win.
- Hover any point to read the exact net worth of both strategies for that year.
When to prioritise debt?
If borrowing costs exceed realistic returns, overpayments almost always win. The calculator shows not only the złoty advantage but also the moment when cashflow is freed for investing.
Monitor the instalment size and amortisation period. A shorter term increases monthly pressure but frees capital sooner.
When to favour investing?
With cheaper debt or high expected returns, investing the surplus can deliver a higher net worth. Watch the break-even threshold – the bigger the spread between returns and interest, the stronger the case for markets.
Use the calculator to test different risk levels. Compare conservative bonds with a dynamic equity portfolio.
What next?
Once you know the direction, switch to the full debt vs investing calculator to add inflation, rate volatility and macro scenarios. You will get a step-by-step action plan.
The detailed calculator also supports sensitivity analysis – set multiple return scenarios and see how often investing keeps the lead.
Open full calculatorHow does the algorithm work?
Monthly simulation
We run detailed month-by-month calculations. Debt interest compounds and investments grow at the chosen rate, so the recommendation reflects compound effects and real repayment pace.
The model also captures balance changes from overpayments and updates the next month’s interest automatically.
Net worth focus
We compare assets minus liabilities instead of looking at debt or investments alone. That is the best metric for long-term financial health.
You can see how quickly assets overtake the remaining loan and how much capital works in your favour.
Break-even threshold
We calculate the exact return where both strategies tie. Use it against historical market data or product offers to judge feasibility.
If the threshold is very high, treat investing as an option only with additional safety nets such as an emergency fund.
How to use the recommendation?
Review the recommendation card and the chart. When net worth values are close, factor in comfort and liquidity before deciding.
Consider rate risk and income stability. A strategy that looks best on paper may still need an extra safety buffer.
Example use cases
- Compare mortgage overpayments with investing in an index fund at a chosen return.
- Analyse whether to clear a consolidation loan before building an ETF portfolio.
- Estimate how long it takes to reach financial neutrality while paying down debt and investing simultaneously.