Total Interest Paid Lifetime
Total interest across all your debts.
Calculate lifetime interest on multiple debts combined. Enter debt 1 balance and debt 1 rate to see total lifetime interest paid across up to 3 debts combined.
What this tool does
This tool calculates total lifetime interest paid across up to 3 debts combined.
Enter Values
Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Lifetime interest on multiple debts adds up quickly. This calculator takes up to 3 debts with their rates plus a total monthly payment, then shows total lifetime interest paid and months to clear.
10k at 18% + 15k at 12% + 5k at 24% with 800/month: weighted rate 16%. Clears in 47 months, total interest 7,240. Increase payment to 1,000 and interest drops to 5,120 (saves 2,120).
Useful for debt consolidation decisions - shows exactly what current path costs so you can compare to consolidation or balance transfer alternatives.
A worked example
Try the defaults: debt 1 balance of 10,000, debt 1 rate of 18%, debt 2 balance of 15,000, debt 2 rate of 12%. The tool returns 11,865.48. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.
What moves the number most
The result responds to Debt 1 Balance, Debt 1 Rate, Debt 2 Balance, Debt 2 Rate, and Debt 3 Balance. Frequency and unit price pull the total in different directions. The biggest surprise for most people is how small recurring amounts compound into large annual figures — that's where this calculation earns its keep.
The formula behind this
Weighted average rate from balances. Standard amortisation on total. Interest = total paid - principal. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.
Why payoff plans work
Debt feels overwhelming when it's an abstract total. Break it into a payoff date and a monthly figure and the problem becomes finite — you can see the finish line. That visibility is what this tool provides, and for many people it's the difference between dithering and acting.
What this doesn't capture
Real payoff journeys include missed payments, fee changes, balance transfers, and promotional rates that reset. The calculation assumes a steady plan; reality is rarely that clean. Use the figure as the best-case plan against which actual progress gets measured.
£10,000 £@18% + £15,000 £@12% + £5,000 £@24% at £800 £/mo = $11,865.48.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Weighted average rate from balances. Standard amortisation on total. Interest = total paid - principal.
Frequently Asked Questions
How to reduce total interest?
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