Loan Payoff Calculator

How Extra Loan Payments Work

Every extra dollar you put toward a loan reduces the principal balance, which reduces the interest charged next month, which means more of every future payment goes to principal. This accelerating effect is why even small extra payments have an outsized impact on payoff time.

Example: $25,000 loan at 6.5%, $485/month payment. Without extra payments: paid off in ~60 months, total interest ~$4,100. With $100 extra/month ($585 total): paid off in ~49 months — 11 months early and saving ~$900 in interest. A modest $100/month extra turns into real time and money.

The Debt Avalanche vs. Debt Snowball

When you have multiple loans, there are two strategies for applying extra payments:

• Debt Avalanche: Target the highest-interest loan first. Mathematically optimal — minimizes total interest paid. Best for people who are motivated by numbers.
• Debt Snowball: Target the smallest balance first regardless of rate. Psychologically optimal — quick wins keep you motivated. Best for people who need momentum to stay on track.

Studies show the Snowball method leads to higher completion rates even though it costs more in interest. The best strategy is the one you'll actually stick to. If you have high-discipline, use Avalanche. If you've tried to pay down debt before and stopped, try Snowball.

When to Pay Off Loans Early (and When Not To)

Pay off early when:

• Loan rate exceeds your investment return rate (credit cards always qualify)
• You want psychological peace of mind and reduced financial risk
• You're approaching retirement and want to reduce fixed obligations
• Prepayment penalties are zero or minimal

Don't rush to pay off early when:

• Rate is below 4–5% and you can earn more investing (mortgage, low-rate student loans)
• You have no emergency fund — build that first before extra loan payments
• You're not getting your full 401(k) employer match — that's a 50–100% guaranteed return
• Loan has large prepayment penalty that offsets interest savings

The break-even math: if your loan is at 4% and you can earn 8% investing, every dollar of extra payment "earns" 4% guaranteed while every dollar invested earns 8% expected. Over 20 years on $10,000, investing beats payoff by ~$4,800. Over shorter horizons or with higher-rate loans, the calculus changes.

One-Time Lump Sum vs. Monthly Extra Payments

A $1,200 annual bonus applied as a lump sum in January is more effective than $100/month extra — because the interest savings accrue from day one rather than averaging across the year. Both approaches save roughly the same over long periods, but timing a lump sum payment early in the loan term maximizes savings. The earlier in the amortization schedule you make extra payments, the higher the impact.