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Student Loan Calculator
Whether you're still in school or already repaying, this student loan calculator finds your monthly payment, payoff date and total interest, shows what an extra payment accelerates, and can project how interest builds before graduation. Generic repayment math only — no program-specific rules.
See how this works on a $78,000 student loan — 3 real examples
While you’re still in school
Monthly payment
$0
Total interest
$0
Total paid
$0
Payoff date
—
What you’ll repay in total
One payment, month by month
- Interest—
- Principal—
Balance over the repayment period
How the repayment term changes your cost
Same balance and rate, different terms. A shorter term means a higher monthly payment but less total interest — your current term is highlighted.
| Term | Monthly payment | Total interest |
|---|
Repayment scheduleMonth-by-month breakdown
How your student loan payoff is calculated
The monthly payment comes from the standard fixed-rate amortization formula, and total interest is simply the sum of every month’s interest charge:
M = P · r(1 + r)n / ((1 + r)n − 1)
r = annual rate / 12 n = repayment years × 12
where P is the balance being repaid. Extra payments are applied entirely to principal each month, with the final payment clamped so the balance lands exactly on zero; interest saved is the difference in total interest between the baseline schedule and the accelerated one.
In the still-in-school projection, interest is modeled as simple (non-compounding) interest: one year of outstanding-principal × r accrues for each in-school year (when accrual is on), giving the balance at graduation; then grace-period interest of graduation-balance × r × grace-months / 12 is added. That accrued interest capitalizes — it’s folded into principal — and the resulting balance is what gets amortized. Assumptions: the rate is fixed for the whole term, annual borrowing is disbursed at the start of each remaining school year, and the first repayment lands one month after any grace period ends. This is strictly generic repayment math with no program-specific rules or eligibility logic.
What a loan does while you're still studying
Three versions of the same 6.5% loan — four years letting interest build, four years paying it as it goes, and a shorter two-year course.
Four years, interest left to build
per month$1,097.35
- $78,000 borrowed becomes $93,600 by graduation day — interest at 6.5% keeps its own schedule during the study years.
- By the time repayment starts, $18,642 of unpaid interest has joined the balance, and the loan is $96,642.
- The ten years of repayment add another $35,040 in interest on top of that.
Nothing is due while studying; the balance starts repayment $18,642 above what was borrowed.
Load this example (opens in a new tab)Same course, interest paid as it goes
per month$914.46
- Covering the interest each month holds the balance at $78,000 right through graduation day.
- Only the grace period adds anything — $2,535 — so repayment opens at $80,535.
- Against the build-up route, that is $182.89 less every month and $5,840 less interest across the ten repayment years.
Same borrowing, a starting balance $16,107 lighter — where paying during study is possible.
Load this example (opens in a new tab)The shorter route: two years of study
per month$706.24
- Two study years instead of four means $54,000 borrowed in total, and less time for interest to work.
- The balance reaches $62,198 by the first payment — $8,198 of that is added interest, less than half the four-year figure.
- Ten years of repayment cost $22,551 in interest — about $12,500 less than the four-year build-up route.
Two fewer years of borrowing take about $391 off every monthly payment.
Load this example (opens in a new tab)Illustrations only, not financial advice. Your own rate, taxes and insurance will differ — check with a qualified financial advisor before acting on any of this.
Paying off student loans, in plain English
- The term sets the trade-off. A 10-year standard term keeps interest low; stretching to 20 or 25 years lowers the monthly payment but can double the interest you pay — pure rate-and-term math you can compare here by changing the term.
- Extra payments punch above their weight. Every dollar over the required payment goes straight to principal, so it stops accruing interest for the rest of the loan — early extra dollars save the most.
- Interest doesn’t wait for graduation. If interest accrues while you’re in school and during the grace period, it capitalizes into your balance, so you end up paying interest on interest.
- Borrowing less costs less twice. A smaller balance means both a lower payment and less interest — the in-school projection shows how each year of borrowing grows what you’ll owe.
- Know your real number. The total-paid figure and the principal-vs-interest split show the true lifetime cost, not just the monthly payment.
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Frequently asked questions
How is my student loan monthly payment calculated?
This student loan calculator uses the standard amortization formula: M = P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is your balance, r the monthly rate and n the number of payments. A $30,000 balance at 6.5% on a 10-year term works out to about $340.64 a month. Choose a longer term and the payment drops but you pay far more interest overall.
How does interest capitalize while I’m still in school or during a grace period?
While you are in school and during any grace period after graduation, interest can build up on your balance. When it capitalizes, that accrued interest is added to your principal, so from then on you pay interest on a larger balance. This calculator uses simple interest for the in-school and grace phases: it accrues one year of interest per in-school year, then grace-period interest on the graduation balance, and folds the total into the amount you repay.
How much can extra payments save me over the life of the loan?
A lot, because every extra dollar goes straight to principal and stops accruing interest. On a $30,000 balance at 6.5% over 10 years, paying an extra $100 a month clears the loan almost 3 years early and saves roughly $3,347 in interest. Enter any amount in the extra-payment field and the payoff date, chart and schedule update instantly.
How is total student loan interest calculated?
Total interest is the sum of every month’s interest charge across the whole repayment, equal to the total of all your payments minus the amount you borrowed. If you started in school, any interest that capitalized before repayment is added on top. This student loan interest calculator shows the full figure and splits your total cost into principal, capitalized interest and repayment interest.
What happens to my balance during the grace period after graduation?
If interest accrues during the grace period, your balance keeps growing even though no payments are due yet. For example, a $40,000 balance at 6.5% over a 6-month grace period adds about $1,300 of interest before your first payment. That amount capitalizes into the balance you repay, which is why a longer grace period raises your lifetime cost.
Does choosing a shorter repayment term save money?
Yes — a shorter term means a higher monthly payment but much less total interest. A $30,000 balance at 6.5% costs about $340.64 a month over 10 years (roughly $10,900 interest) versus about $223.67 a month over 20 years (roughly $23,700 interest). This is plain rate-and-term math: the faster you repay, the less interest compounds against you.
Disclaimer: these calculators are educational tools, not financial advice. They model your inputs with published formulas, but they cannot know your full situation — for decisions with real stakes, talk to a qualified professional. Formulas and defaults last reviewed .