TL;DR
For the number that will actually appear on your payslip, use the Calc Garden student loan repayment calculator: pick Plan 1, 2, 4, 5 or Postgraduate, enter your gross salary, and it shows the monthly and annual deduction against the 2026/27 threshold in your browser. For a lifetime projection instead, including interest, salary growth, overpayments and whether the balance is written off before you clear it, student-loan-calculator.co.uk is the stronger free tool. This is not an "only free one" claim: that tool and The Salary Calculator are both free and need no account.
The 2026/27 thresholds, which is what the answer hinges on
A UK student loan is income-contingent, so the calculation has nothing to do with how much you borrowed. You repay a fixed percentage of whatever you earn above your plan's threshold, and that is it. Every calculator worth using runs the same two lines of arithmetic, which means the only thing that can make one wrong is stale threshold figures. These are the numbers gov.uk publishes for the 2026/27 tax year.
| Plan | Who is on it | Annual threshold (2026/27) | Rate above threshold |
|---|---|---|---|
| Plan 1 | England and Wales before September 2012, most Northern Ireland | £26,900 | 9% |
| Plan 2 | England and Wales, September 2012 to July 2023 | £29,385 | 9% |
| Plan 4 | Scotland | £33,795 | 9% |
| Plan 5 | England, courses starting on or after 1 August 2023 | £25,000 | 9% |
| Postgraduate Loan | Master's and doctoral loans, repaid alongside any other plan | £21,000 | 6% |
Two of those moved in ways worth knowing about. The Plan 2 threshold had been frozen at £27,295 since 2023, which quietly raised repayments every year as salaries rose; it has now been unfrozen to £29,385, so a Plan 2 graduate on £34,000 pays around £16 a month less than they did on the frozen figure. Plan 5, by contrast, stays pinned at £25,000, which is why a Plan 5 graduate on the same salary pays roughly twice what a Plan 2 graduate pays. If a calculator still shows £27,295, it is out of date and will overstate your Plan 2 deduction.
The best free UK student loan repayment calculators compared
Cells describe each tool as checked in July 2026. "Partial" means the capability is present but limited. The pricing row reflects each product as of 2026.
| Capability | Calc Garden | student-loan-calculator.co.uk | The Salary Calculator | GOV.UK account |
|---|---|---|---|---|
| Price (as of 2026) | Free, no signup | Free, no signup, optional donation | Free, no signup | Free, sign-in required |
| Works without an account | Yes | Yes | Yes | No |
| Covers Plans 1, 2, 4, 5 and Postgraduate | Yes | Yes | Yes | Yes |
| Monthly deduction from a salary | Yes | Yes | Yes | No |
| Shows the threshold and rate used | Yes | Partial | No | Yes |
| Lifetime total repaid and write-off date | No | Yes | No | No |
| Models interest on the balance | No | Yes | No | Yes, your real accrued interest |
| Overpayments and salary growth | No | Yes | No | No |
| Full payslip with tax, NI and pension | No | No | Yes | No |
| Your real outstanding balance | No | No | No | Yes |
| Runs entirely in your browser | Yes | Not stated | Not stated | No |
| Lands with a worked example filled in | Yes | No | No | No |
Read that honestly, because each column wins somewhere. student-loan-calculator.co.uk is the most capable free tool of the four for planning: it takes your debt and course dates as well as your salary, applies interest, lets you model overpayments and salary growth, and projects the payoff date against the write-off point. That is the only one of the four that can answer "will I ever actually clear this?". The trade is that it needs a lot more inputs, including a debt figure most people have to go and look up.
The Salary Calculator is the right tool when the student loan is one line among several. It supports all five plans and shows the deduction next to income tax, National Insurance and pension on annual, monthly, weekly and daily bases, which is what you want when you are checking a payslip or comparing job offers. It does not print the threshold it used, so you cannot see the working. Your GOV.UK student loan account is not a calculator at all, but it is the only source of your real balance, your real accrued interest and confirmation of which plan you are on, so it is worth signing into once even though the other three do not ask you to.
Where Calc Garden wins is being lean and transparent. It asks for two things, a salary and a plan, and returns the monthly repayment, the annual repayment, the threshold it applied and the deduction as a percentage of your whole salary. It lands with a worked example already in the fields, so the page answers the question before you type, and it runs client-side, so a real salary never leaves your browser. If your question is simply "what comes off my pay?", that is the shortest honest route to it. If your question is about the lifetime cost, it is the wrong tool and the guide above points you at the right one.
The formula, with a worked example
Annual repayment equals your gross salary minus the plan threshold, times the plan rate, and never less than zero. The monthly deduction is that divided by twelve. Nothing else enters the sum, which is why the amount you borrowed is irrelevant to the monthly figure.
Take a graduate on £34,000 on Plan 5. The threshold is £25,000, so £9,000 is above it. Nine percent of £9,000 is £810 a year, or £67.50 a month, and that is 2.4 percent of the whole salary. The same person on Plan 2 has a £29,385 threshold, so only £4,615 is above it: £415.35 a year, or £34.61 a month. Add a Postgraduate Loan and a second deduction runs alongside at 6 percent above £21,000, which on £34,000 is another £780 a year, or £65 a month, on top of the undergraduate plan. Calc Garden's student loan repayment calculator runs each of those in turn as you switch plan, and prints the threshold it used so you can check it against gov.uk yourself.
One consequence catches people out at pay review time. Because the deduction is 9 percent of the amount above the threshold, a pay rise costs you 9 pence in the pound on top of income tax and National Insurance, so a £2,000 rise on Plan 5 adds £180 a year of repayment. To see that landing alongside everything else, run the raise through the UK salary take-home calculator, keeping in mind that it models income tax and National Insurance only, so add the student loan figure from the loan calculator on top.
When the repayment figure is not the number you need
A monthly deduction is the right answer for budgeting, for checking a payslip and for comparing two job offers. It is the wrong answer for the question people most often ask next, which is whether to overpay. Because an unpaid balance is cancelled 30 years after you were first due to repay on Plan 2, or 40 years on Plan 5, plenty of graduates will pay the 9 percent for their whole working life and never clear the debt. For them, voluntary overpayment is money handed over that would never have been collected. Only a lifetime projection that models interest and future salary can tell you which group you are in.
The deduction does matter for borrowing. Lenders treat it as a committed outgoing, so it reduces what a mortgage affordability check will offer you. If you are working out what you can borrow, feed the monthly figure in as a fixed commitment using the debt-to-income ratio calculator, and what is a good debt-to-income ratio explains the thresholds lenders actually apply.
Which one to open
Open the Calc Garden student loan repayment calculator when you want the payslip deduction in a couple of seconds with the threshold shown and nothing to sign up for. Open student-loan-calculator.co.uk when you are deciding whether to overpay and need interest, write-off and salary growth modelled. Open The Salary Calculator when you want the loan shown inside a full payslip next to tax, National Insurance and pension, and the free alternative to The Salary Calculator guide compares those two in more depth. Sign in to your GOV.UK student loan account once to confirm your plan and your real balance. The guides index collects the rest.