Student Loan Calculator

What this calculator is, and when to reach for it

Student debt is unlike every other loan on this site, because it was taken on before the borrower had any income to judge it against, and it is repaid over a period long enough for a career to change shape several times. That combination makes it the debt people understand least well and worry about most.

This page models the straightforward case: a fixed rate, a standard repayment term, equal monthly payments until the balance clears. That is the baseline every other arrangement is measured against, and it is the right starting point even if your eventual plan is different, because it tells you what the debt costs when nothing unusual happens.

What it deliberately does not model is the machinery that surrounds student lending in many countries — income-driven plans, forgiveness after a qualifying period, subsidised interest during study, deferment, and the rules that govern when unpaid interest is added to the balance. Those vary enormously by country and by scheme, and a calculator that quietly assumed one country’s system would mislead everyone else.

Reach for this page to see the true cost of the standard path, to test what a shorter term or an overpayment would do, or to establish the baseline figure you will compare an income-driven plan against.

The two questions worth separating

The first is what the loan costs. That is arithmetic, and this page answers it. The second is what you should do about it, which depends on the scheme you are in, whether forgiveness is realistically available to you, and what else competes for the same money.

Conflating them is where most confusion lives. A borrower on a scheme where the balance is written off after a qualifying period may be actively worse off overpaying, because they would be repaying money that was going to be forgiven. A borrower on a straightforward commercial loan is in the opposite position, and overpaying is straightforwardly good.

Work out the cost first, then apply the rules that govern your particular loan. The order matters, because the cost is the one part that is the same for everyone.

Where to go next

To see what overpaying achieves on a fixed-rate balance, the loan repayment calculator models a regular extra payment directly. For the same amortization arithmetic in other contexts, the personal loan calculator and auto loan calculator apply it to different purposes.

If you hold several loans at different rates, the loan comparison calculator helps rank them, and the debt consolidation calculator tests whether combining them helps — though consolidating government-backed student debt into a commercial loan usually forfeits protections that are worth more than the rate saving.

Because student payments count in lending assessments, the debt-to-income calculator shows their effect on borrowing capacity, and the affordability calculator shows what that means for a property purchase.

How the repayment is worked out

A fixed rate, a fixed term, and equal payments. The same amortization formula that governs a mortgage governs this.

M = P × [ r(1 + r)ⁿ ] ÷ [ (1 + r)ⁿ − 1 ]

P

the balance outstanding when repayment begins

r

the monthly rate, being the annual rate divided by twelve

n

the number of monthly payments in the repayment term

Why the starting balance is often larger than you borrowed

On many schemes interest accrues while you are studying and during any grace period afterwards. If it is not paid as it arises, it is commonly added to the balance when repayment begins — a process called capitalisation — so you start repaying a figure larger than the sum advanced.

From that point onward interest is charged on the capitalised total, including the interest that was rolled in. Enter the balance as it stands when repayment starts rather than the amount originally borrowed, or the result will understate the cost.

What the term does to the total

Extending a student loan is the most common way to make the payment manageable, and it is expensive. The payment falls because the same balance is spread across more periods, while interest accrues for longer on a balance that reduces more slowly.

The effect is large enough to be worth quantifying rather than assuming. On the example below, stretching a ten-year term to twenty-five cuts the payment by about 40% and nearly triples the interest paid.

Where overpayments go, and why it matters

An extra amount should reduce the principal, but on student loans this is less automatic than elsewhere. Servicers commonly apply an unexplained excess to future instalments, or spread it across multiple loans in a portfolio, and either behaviour wastes most of the benefit.

Where you hold several loans at different rates, directing overpayments at the highest-rate balance rather than letting them be spread evenly makes a substantial difference. It usually requires an explicit instruction to the servicer.

Why this page stays deliberately narrow

Income-driven repayment, forgiveness, subsidised interest, deferment, and forbearance are all real and all consequential, and they differ so completely between countries and schemes that modelling one would mislead users of every other. A calculator that silently assumed a particular national system would be worse than one that is clear about its scope.

What a fixed-rate baseline gives you is a defensible comparison point. Whatever scheme you are in, knowing what the standard path costs lets you judge whether an alternative is genuinely better or merely more comfortable each month.

What this page assumes

The calculator works out a level monthly payment from your balance, then steps through each month, applying any extra payment after interest.

Each month, interest equals prior balance times monthly rate. Principal equals the lesser of scheduled payment plus extra payment less interest, or the remaining balance.

Worked examples, step by step

Take a 35,000 balance at 6.5% repaid over a standard ten-year term.

Ten years against twenty-five

The ten-year path costs 12,690.15 in interest. Stretching to twenty-five years reduces the payment by 161.10 a month, which is genuinely meaningful early in a career, and raises total interest to 35,896.75 — more than the original balance and nearly three times the ten-year figure.

Neither is wrong. A payment you can actually sustain beats an ambitious one you cannot, and there are years when 161 a month is the difference between coping and not. But the longer term should be chosen knowing it costs an additional 23,206.60, rather than because it was the option presented.

What a modest overpayment does

On the ten-year plan, the first month’s interest is 35,000 × (0.065 ÷ 12) = 189.58, so of the 397.42 payment, 207.84 reduces the balance. Just over half the payment is doing real work from the very first month — a far healthier ratio than a long mortgage or a credit card.

That ratio is why student loans respond well to overpayment early. Because the term is comparatively short, the balance falls quickly, and each extra unit paid in the first years removes interest that would otherwise have accrued across most of the loan’s life.

The vocabulary, on and around this page

Standard repayment

Equal monthly payments over a fixed term until the balance clears. It is the baseline that other repayment arrangements are measured against.

Capitalisation

Unpaid interest being added to the principal, so future interest is charged on it too. It commonly happens when repayment begins.

Grace period

A window after study before repayment starts. Interest often continues to accrue during it depending on the scheme.

Subsidised interest

An arrangement where a government or institution pays the interest during study or deferment, so the balance does not grow.

Deferment

An authorised pause in repayment. Interest may or may not accrue during it, which is the detail that matters most.

Forbearance

A temporary reduction or suspension of payments, usually with interest continuing to accrue and capitalise afterwards.

Income-driven repayment

A plan where the payment is set as a share of income rather than by the balance. Not modelled here, as the rules vary by country.

Forgiveness

Cancellation of a remaining balance after a qualifying period or service. Where it applies, overpaying can be counterproductive.

Servicer

The organisation that collects payments and administers the loan, which may not be the original lender.

Principal

The balance on which interest is charged. Enter it as it stands when repayment begins, not the amount originally advanced.

Amortization

The schedule by which each payment covers interest first and reduces the balance with the remainder.

Repayment term

The number of months over which the loan is scheduled to clear. Extending it lowers the payment and sharply raises interest.

Refinancing

Replacing student debt with a new commercial loan. It can lower the rate but usually forfeits scheme-specific protections permanently.

Consolidation

Combining several student loans into one. Within a government scheme it may preserve protections; into a commercial loan it generally does not.

Weighted average rate

The blended rate across several balances. Useful when deciding which loan to target with overpayments.

Overpayment allocation

How a servicer applies an extra amount. Without instruction it may prepay future instalments or spread across loans rather than cutting principal.

Total repaid

Every payment added together. On long terms it can substantially exceed twice the amount originally borrowed.

Debt to income

The share of gross income committed to debt payments. Student payments count, affecting mortgage and other borrowing.

Fixed rate

A rate that does not change for the life of the loan, which is the assumption this page models.

Variable rate

A rate that can move over time, common on refinanced private student debt. Projections beyond the current rate are illustrative only.

Common mistakes, and what this page will not do

• Entering the amount borrowed rather than the current balance. Interest accrued during study is often capitalised when repayment starts, so the starting balance is commonly larger than the sum advanced.
• Choosing a long term without pricing it. Stretching the example from ten years to twenty-five saves 161.10 a month and costs an extra 23,206.60 in interest.
• Overpaying without instructing the servicer. An unexplained excess is often applied to future instalments or spread across loans instead of reducing principal.
• Spreading overpayments evenly across several loans. Targeting the highest-rate balance first saves materially more than an even split, but it usually requires an explicit instruction.
• Overpaying when forgiveness is realistically available. On schemes that cancel a remaining balance after a qualifying period, repaying faster can mean repaying money that would have been written off.
• Refinancing government debt without weighing what is lost. A commercial loan may offer a lower rate while permanently forfeiting income-driven options, deferment rights, and any forgiveness.
• Assuming a pause in payments is a pause in interest. Under many arrangements interest continues to accrue during deferment or forbearance and is capitalised afterwards.
• Treating this baseline as your actual plan. This models standard fixed-rate repayment only. Income-driven schemes behave quite differently and vary by country.
• Forgetting the payment affects other borrowing. Student payments count toward debt-to-income and can materially reduce the mortgage a lender will offer.

What this calculator leaves out: This calculator models standard fixed-rate repayment only. It does not include income-driven plans, forgiveness or cancellation, subsidised interest, deferment or forbearance, interest capitalisation, tax relief on interest, or any country-specific student lending programme. Enter the balance as it stands when repayment begins.

Frequently asked questions