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Student loans

Student Loan Payoff Calculator

See your real payoff date, what you'll pay in total interest, and how much faster you'll be done if you put even a little extra at it each month.

How the Student Loan Payoff Calculator Works

Enter your current balance, interest rate, and either your monthly payment or target payoff window. The calculator runs a full month-by-month amortization — the same math your loan servicer uses — to show exactly when you'll make your final payment and how much interest you'll pay along the way.

Flip to “I know my term” mode if you want to work backwards: set a payoff window (say, 7 years) and the calculator derives the required monthly payment. Use the extra monthly payment slider to model what happens if you add $50, $100, or $200 on top of your base payment — the interest-saved and months-saved figures update instantly.

The Formula

Student loan amortization uses the standard fixed-payment loan formula. Your monthly interest rate is your APR divided by 12. Each month, the interest charge is your current balance multiplied by that rate. The rest of your payment reduces principal. That's it — the same formula used for mortgages, auto loans, and every other amortizing loan.

If you know your term and need to find the payment, the formula is:

payment = balance × r × (1 + r)^n / ((1 + r)^n − 1)

where r is the monthly rate (APR ÷ 12) and n is the number of months. If you know your payment and need the term, solve for n:

n = −log(1 − balance × r / payment) / log(1 + r)

One edge case matters: if your payment is less than or equal to the monthly interest charge, the balance never falls — the calculator surfaces a “will never pay off” warning. Raise the payment or switch to term mode.

Worked Example

Suppose you have a $45,000 balance at 6.8% APR and your current payment is $400 per month.

  • Without extra:167 months (13.9 years) to pay off. Total interest: $21,800. Payoff date roughly October 2039.
  • With $100/mo extra:122 months (10.2 years) to pay off. Total interest: $14,200. Payoff date roughly January 2036.
  • Savings:$7,600 in interest and 45 months off your timeline — by paying just $100 more per month. That's roughly $3.30 a day.

The earlier you make extra payments, the bigger the impact — because more of each early payment goes to interest when the balance is high. A $100 extra payment in month 1 saves more than the same $100 in month 100.

When to Use This Calculator

Use it any time you're making a decision about your student loans:

  • Before choosing a repayment plan — compare standard 10-year vs extended 25-year payments side by side.
  • When you get a raise or bonus — model how a lump-sum or ongoing extra payment changes your payoff date.
  • Before refinancing — run your current loan vs the refinanced terms to see the true break-even.
  • When switching from income-driven repayment to standard — see what the accelerated payoff costs per month and saves in total interest.
  • For annual loan checkups — paste in your current balance each year and see your updated payoff date.

Key Concepts

Amortization
The process of paying off a loan in equal periodic payments. Early payments are mostly interest; later payments are mostly principal. This is why extra early payments are so powerful — they permanently reduce the principal the interest is calculated against.
APR (Annual Percentage Rate)
The yearly interest rate expressed as a percentage. For student loans, APR and interest rate are typically the same since fees are rare. Divide by 12 to get the monthly rate applied to your balance each month.
Principal
The outstanding loan balance — the amount you actually borrowed minus everything you've paid back so far. Interest is calculated as a percentage of principal, so reducing principal faster is the key to cutting total interest paid.
Debt Avalanche vs Debt Snowball
If you have multiple loans, the avalanche method targets the highest-rate loan first (minimizes interest paid), while the snowball method targets the smallest-balance loan first (maximizes motivation). Run each loan individually in this calculator, then prioritize the highest-rate one for extra payments.

Common Mistakes

  • Refinancing federal loans without understanding what you lose. Private refinancing permanently eliminates access to income-driven repayment, PSLF, and federal deferment. Run the numbers carefully before making an irreversible move.
  • Paying extra before building an emergency fund. If you have less than three months of expenses saved, an unexpected expense will force you to carry high-interest credit card debt — which costs far more than your student loan rate.
  • Using the snowball method on high-rate debt. Paying off the smallest loan first feels satisfying, but if that loan has a lower rate than your others, you're maximizing motivation at the expense of math. Use the debt payoff calculator to compare strategies.
  • Skipping the 0.25% auto-pay discount. Most federal servicers and many private lenders reduce your rate by 0.25 percentage points when you enroll in auto-pay. On a $30,000 loan that's roughly $300–$500 saved over the repayment period, for zero effort.
  • Modeling only principal, not principal + interest. Your loan payoff strategy should account for total cost, not just which loan disappears first. Use this calculator alongside the compound interest calculator to compare the opportunity cost of paying down loans vs investing.

Frequently Asked Questions

What's a typical student loan interest rate?
Federal undergraduate loans disbursed in 2025–2026 carry a 6.54% fixed rate. Graduate PLUS loans run around 9.08%. Private loan rates range from roughly 4% to 14% depending on credit score and cosigner status.
Should I pay extra on my student loans?
If your interest rate exceeds what you'd earn investing — typically around 7% long-term in a diversified index fund — extra payments win on a pure math basis. Below that threshold, prioritize maxing out tax-advantaged retirement accounts first. Either way, make sure you have a three-to-six month emergency fund before throwing windfalls at the loan.
Does refinancing student loans make sense?
Refinancing federal loans into a private loan permanently locks out income-driven repayment plans (IBR, SAVE, PAYE), Public Service Loan Forgiveness (PSLF), and federal deferment and forbearance options. Only refinance if you're confident you'll never need those protections — for example, if you're a high earner on a standard repayment track with no plans to pursue PSLF.
How is the payoff date calculated?
The calculator amortizes your balance month by month. Each period, it applies your APR divided by 12 to the current balance to get that month's interest charge. The remainder of your payment reduces principal. It repeats until the balance reaches zero. The date of the final payment is your payoff date.
Can I model multiple loans at once?
For best accuracy, model each loan separately, then sum the monthly payments. Blending loans with different rates into one calculation obscures which loan costs the most and can lead to suboptimal payoff ordering. The avalanche method — targeting the highest-rate loan first — minimizes total interest paid.
What happens with biweekly payments?
Paying half your monthly payment every two weeks results in 26 half-payments per year — the equivalent of 13 full monthly payments instead of 12. That extra payment each year can shave 3–6 years off a 10-year standard loan and save thousands in interest. To model this here, divide your monthly payment by 12, multiply by 13, then enter that as your monthly equivalent.

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