How the rate changes the cost

The saving is forward-looking

Interest already paid is sunk. Calculate the original remaining schedule from today, then rebuild it with each extra payment on its expected posting date.

Allocation controls the result

A servicer may treat extra money as a future installment unless directed otherwise. Check the statement for a principal reduction and retain the instruction.

$25,000 at 8% with 60 months remaining

Rate input
Scheduled payment: about $507
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Extra principal: $100 each month
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Illustrative payoff: about 48 months
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Roughly one year removed
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Confirm allocation and exact daily-interest timing

Illustrative calculation. Rounded values can differ from a lender or card issuer schedule.

This decision belongs in The Real Cost of Borrowing. Use Amortization Explained With the Balance You Still Owe to check the next assumption, then test the numbers in the Loan Early Payoff Calculator.

Mortgage borrowers should also compare extra principal with a formal mortgage recast when monthly-payment relief matters as much as interest saved.

Interpret the result in context

Liquidity has value

Paying debt is not reversible. Compare avoided interest with the need for emergency cash and with higher-rate obligations.

Daily interest changes exact dollars

A monthly model is useful for planning, but actual savings can differ when interest accrues daily and payments post on different dates.

Inputs that change the answer

Extra payments save interest only when they reduce principal as expected. Confirm allocation and compare the guaranteed loan saving with the liquidity you give up.

Records for an extra-payment plan

  • Current payoff, APR and remaining scheduled payments.
  • Servicer rule for principal-only and partial payments.
  • Emergency reserve left after any lump sum or recurring extra.
  • Obtain the current principal and payoff terms.
  • Recreate the remaining scheduled amortization.
  • Place extra payments on realistic dates.
  • Verify principal-only treatment and any penalty.
  • Compare interest saved with the cash reserve surrendered.

Rebuild the calculation with your terms

Loan Early Payoff Calculator

Measure interest saved and months removed without treating a future payment as guaranteed.

Where rate comparisons go wrong

  • Using the original loan amount instead of today's balance.
  • Counting future extra payments as certain.
  • Ignoring a prepayment penalty.
  • Assuming an advanced due date means principal was reduced.

Questions this decision usually raises

Should I make one lump sum or monthly extras?

Earlier principal generally avoids more interest, but liquidity and contract rules can change the practical choice.

Will the required payment fall?

Usually not without a recast or modification; the loan generally ends earlier instead.

Does this work for credit cards?

The principle applies, but revolving daily balances and new purchases require a card-specific model.

Check the rules and definitions

This page explains a calculation, not a personal recommendation. Contract rules and consumer protections vary by product and jurisdiction. Check the current agreement and official guidance before acting.