Debt payoff vs invest calculator

Compare compound investment growth with compound interest avoided by paying down the same lump sum.

On your device · No account

Privacy details

Debt payoff vs invest calculator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

Copy link includes the inputs you choose to share in the address. Anyone with that link can reopen them. Files and generated results are excluded. Password and key tools share settings only.

Lump sum available

Debt effective annual rate (%)

More inputs and assumptions

Investment effective annual return (%)

Years compared

Answer

…

Compare compound investment growth with compound interest avoided by paying down the same lump sum.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

Uses constant effective annual rates and assumes the compared debt would otherwise compound without repayment over the horizon. This deliberately simplified comparison omits amortization and minimum payments. Investment returns are uncertain. Fixed assumptions only: no taxes, fees, changing returns, guarantees or product eligibility. Amounts share one currency.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

Scratch calculator

Check another calculation

Use +, −, ×, ÷, parentheses and %. A percentage is divided by 100. This does not change the main tool.

Reset reloads the tool with its starting values and releases open files and device controls. Saved drafts stay on this device until you delete them.

Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.

Keyboard shortcuts

Updated 2026-09-26

Using Debt payoff vs invest calculator

Compare compound investment growth with compound interest avoided by paying down the same lump sum.

Next: Credit card payoff calculator

A worked example

Example inputs: lump sum available = 1000, debt effective annual rate (%) = 10, investment effective annual return (%) = 5, years compared = 1. Investment gain minus avoided interest = -50.

Before you use the result

Example results for lump sum available

These examples use Debt effective annual rate (%): 10; Investment effective annual return (%): 5; Years compared: 1. They are reference calculations, not recommended settings.

Lump sum available	Investment gain minus avoided interest
500	-25
1000	-50
2000	-100

Cite this page

Citation style

ToolOctopus. “Debt payoff vs invest calculator.” Updated 2026-09-26. https://tooloctopus.com/debt-payoff-vs-invest-calculator.

Add an access date if your instructions require one.

Citation formatting uses citeproc-js by Frank Bennett and Citation Style Language styles. Licence and source code.