Student Loan Total Interest Calculator

A 30,000 student loan at 7% interest with 400 monthly payments takes around 8.2 years to clear and costs 9,576 in interest — about a third the original balance again. Smaller payments stretch repayment longer and add far more interest; larger payments compound the saving.

What the result means

Total interest is the cost of the borrowing on top of the principal. Time to clear shows how long the schedule runs. Run the math at a higher monthly payment to see how much interest could be cut by accelerating repayment.

Income-contingent loans where unpaid balance is forgiven after a fixed period work differently — they need a separate calculator that models forgiveness. This tool assumes the balance must be cleared in full.

A worked example

Try the defaults: current balance of 30,000, annual interest rate of 7%, monthly payment of 400. The tool returns 9,575.61. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.

What moves the number most

The result responds to Current Balance, Annual Interest Rate, and Monthly Payment. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

The formula behind this

Standard amortisation: months to clear is computed from the loan-payoff formula. Total paid is monthly payment times months. Total interest is total paid less original balance. Income-contingent or forgiveness rules are not modelled. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.

Using this in pay negotiations

Knowing the exact figure behind a headline rate gives you specific numbers to anchor to in conversations about pay. "The difference is £X per month after tax" lands harder than "a couple of grand a year". Concrete numbers move decisions.

What this doesn't capture

Tax bands, pension contributions, student-loan deductions, and benefits-in-kind sit outside this calculation. The figure is the headline; your actual position depends on local tax rules and personal circumstances. Pair with a dedicated take-home calculator for the full picture.