How Much Is That Extra $100 Really Worth?

Paying extra is smart. Paying a lower rate is smarter.

If you're carrying a rate above 10% p.a., there's a real chance you could refinance to a better deal and stack interest savings on top of what extra repayments already deliver. Check what you'd be offered — no credit score impact, 60 seconds.

How this Extra Repayments Calculator works

The calculator starts by building a standard amortisation schedule based on your loan balance, interest rate, term, and repayment frequency. An amortisation schedule breaks each repayment into two parts: the interest accrued on the outstanding balance during that period, and the principal being repaid. In the early stages of a loan, the interest component is proportionally high because the balance is at its peak. As the balance falls, interest charges reduce and more of each repayment hits principal. This is standard reducing-balance interest — how almost all personal loans in Australia are structured.

Once the baseline schedule is built, the calculator constructs a second schedule using the same inputs but with your extra repayment added each period. Every extra dollar goes directly to principal. A lower principal balance means less interest accruing next period. Less interest next period means more of the standard repayment also hits principal. This compounding effect is what causes a relatively modest extra payment to generate a disproportionately large interest saving over time. The earlier in the loan term you start, the greater the benefit.

For one-off lump sums, the calculator reduces the outstanding balance by the lump sum amount at the start of the next period and recalculates the remaining schedule from that point. A lump sum applied in month 3 of a 60-month loan generates savings across 57 remaining periods. The same amount applied in month 48 saves interest across only 12 periods — still meaningful, but materially less.

If you've entered an early payout fee, the calculator subtracts it from the gross interest saving to show your net saving. This is critical for fixed-rate loan holders. Some fixed-rate personal loans in Australia charge a break cost or early repayment fee that can be significant. Variable-rate personal loans typically allow unlimited extra repayments without penalty — but always verify with your lender or product disclosure statement before assuming.

How to interpret your results

• Interest saved — this is the real number. It's money that stays in your account instead of going to the lender. On a $20,000 loan at 10% p.a. over 5 years, the standard monthly repayment is approximately $425 and total interest is approximately $5,497. Adding $100/month saves roughly $1,200 and cuts the term by around 12 months.
• New payoff date — make it a target, not a projection. A concrete payoff date changes your relationship with the loan. It's not "someday"; it's a specific month. Building a repayment plan around that date — and automating it — is how loans get paid off ahead of schedule.
• The snowball effect — early extra payments are worth the most. A $1,000 lump sum applied in month 6 of a 60-month loan generates savings across 54 remaining periods. The same $1,000 applied in month 48 saves across only 12 periods. Applying a windfall now rather than later is the highest-return decision available to you.
• Total saving after fees — the honest net figure. If your loan is fixed-rate and carries an early repayment fee, gross interest saving overstates what you actually keep. If the fee exceeds the interest saving, continuing with your scheduled repayments may be the better call.
• Worked example. $25,000 loan, 11% p.a., 5 years. Standard monthly repayment: ~$543. Total interest over term: ~$7,600. Adding $150/month in extra repayments saves ~$2,200 in interest and shortens the loan by ~15 months.

How to find extra money for repayments

• Round up to the next $50 or $100. If your scheduled monthly repayment is $418, round it to $450 or $500. Set it up as an automatic transfer on payment day so it runs without ongoing willpower.
• Direct every windfall straight to the loan. Tax refunds, bonuses, cash gifts. The average Australian tax refund is over $2,500 — applied early on a $20,000 loan at 10% p.a., that single payment can save around $1,800 in interest and cut ~8 months off the term.
• Switch from monthly to fortnightly repayments. 26 fortnights per year vs 12 months — fortnightly repayments at half the monthly amount are equivalent to making 13 monthly payments per year instead of 12.
• Audit subscriptions and redirect savings. Cancelling unused streaming services and redirecting $30–$60/month to extra repayments has real long-term impact — set up a second direct debit on the day the subscriptions used to charge.
• Automate the extra payment. Discipline is a depleting resource. Automation is not. Schedule it on the same date as your regular repayment and don't think about it again.
• Even $25/week makes a genuine difference. On a $20,000 loan at 10% p.a. over 5 years, $25/week (~$108/month) saves ~$1,350 in interest and shortens the loan by ~13 months — about $3.57/day.

The win is not "I'll pay extra whenever there's something spare"; the win is "I've set up an automatic extra payment on the same day as my regular repayment and I've never had to think about it again."

Example Extra Repayments Calculations in Australia

All scenarios based on a $20,000 personal loan at 10% p.a. over 5 years. Standard monthly repayment ~$425. Total interest on standard schedule ~$5,497.

Calculator assumptions

This calculator uses standard reducing-balance amortisation and assumes a constant interest rate throughout the loan term. Results are estimates. Actual savings may differ due to lender-specific calculation methods, fee structures, rounding conventions, rate changes on variable-rate products, and the precise timing of extra payments relative to your lender's interest calculation dates. The calculator does not account for establishment fees or ongoing monthly fees beyond the early payout fee field provided. For fixed-rate personal loans, extra repayment conditions and fees vary significantly between lenders — always review your product disclosure statement or call your lender before making additional payments. Variable-rate personal loans in Australia generally allow unlimited extra repayments without penalty, but confirm this with your lender. Rates referenced are indicative as of May 2026. Reviewed by the LoanGorilla editorial team — last updated May 2026.