Tool · Investor Sam Bigpurchase

One Extra Payment Savings Calculator

July 1, 2026 • By the Investor Sam Editorial Team • Reviewed by Berly Sam Varghese, Editor
Extra money applied to a loan goes straight to principal, cutting the interest that would have accrued on it for the rest of the term. This tool shows how a modest extra payment can shave months — sometimes years — and thousands of dollars off any loan.

Example: Current loan balance: 22000 $ · APR: 7 % · Months remaining: 60 · Extra payment/mo: 150 $

Interest you save$1,232
Months you cut17
New payoff in months43
Original total interest$4,138

Worked example

On a $22,000 balance at 7% with 60 months left, adding $150 a month pays the loan off roughly 13 months early and saves around $1,500 in interest. The extra payment attacks principal directly, so every added dollar earns you a guaranteed return equal to the loan’s rate.

Frequently asked questions

Why does paying extra save so much?

Interest is charged on the remaining balance. Extra payments cut that balance immediately, so all the interest that balance would have generated for the rest of the term simply never accrues.

Is there a prepayment penalty?

Most auto and personal loans have none, but some contracts do — check yours before committing. If a penalty exists, weigh it against the interest saved shown here.

Should I pay extra or invest it?

Compare the loan’s rate to your expected after-tax investment return. Paying down a high-rate loan is a guaranteed, risk-free return; for low-rate loans, investing the extra may win. The debt-vs-invest tools help you decide.

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Sources

Berly Sam Varghese · Editor, Investor Sam

Berly Sam Varghese is an engineer who treats money the way he treats any hard problem — something to be engineered, not gambled on. He funded years of education and built real financial stability the patient way, by living below his means and investing rather than borrowing. He writes for the person weighing a big purchase and the trade-offs behind it. He reviews and approves every article on Investor Sam and checks the figures against primary sources before anything is published. More about our standards.