Financial decision guide and interactive simulator

Debt versus investing calculator

Should extra cash earn a market return or remove guaranteed debt interest?

What this calculation is designed to show

Debt repayment produces a predictable saving equal to avoided interest, while investment returns are uncertain and may be taxed. Emergency liquidity and payment risk belong in the comparison as well.

How to test the decision

Compare the debt rate with a conservative after-tax investment return. If the decision is close, test a split contribution and a lower market return rather than assuming the best historical outcome.

Using the result responsibly

Change one important assumption at a time and compare a cautious case with the expected case. The interactive calculator below updates from the values you enter. Its output is an educational estimate, not financial, tax, legal or investment advice.

Read the calculation methodology or learn about The Finance Check.