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
- 6,5%
- Net worth – repay
- 256 624 zł
- Net worth – invest
- 259 627 zł
- When cash is freed
- 4.0 years
Above this expected return, investing pulls ahead.
Assets after overpaying debt and investing the freed instalment.
Capital after investing the surplus while paying the minimum instalment.
Estimated moment when debt disappears with overpayments.
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.
📈 Investing wins
Investing 1500 zł monthly can build a portfolio about 3003 zł higher over 10 years. The overpayment variant can eliminate the debt in roughly 4.0 years, freeing 2863 zł per month (1363 zł instalment + 1500 zł surplus) for investing.
Financial advantage
3003 zł
Difference once the break-even return 6,5% is exceeded.
Break-even return
6,5%
Above this return, investing starts to look stronger.
Instalment for 120 000 zł
1363 zł
Minimum instalment required to repay within the horizon.
Investing strategy
259 627 zł
Assets: 259 627 złDebt remaining: 0 zł
Debt repayment strategy
256 624 zł
Assets after payoff: 256 624 złDebt fully repaid
With these inputs the debt disappears in about 4.0 years, letting you invest the full amount.
We compare how fast your net worth grows after clearing the debt versus investing the surplus while paying the minimum instalment.
The lines show net worth (assets minus remaining debt) at the end of each year.
Vertical highlights make it easier to spot when the lead changes. A sharp rise of the green line means the debt is gone and the instalment shifts into investments.
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 full version 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.