A fixed interest rate is set when the loan is drawn and stays put for the agreed term, whatever the OCR, the market or the lender’s appetite does next. The repayment calculated on day one is the repayment on the last day.
For consumer lending, that certainty is most of the point: a fixed repayment can be built into a fortnightly budget and forgotten, and the finish date is real rather than indicative. It is the opposite of revolving credit, where rates float, minimums move and the end date is wherever your discipline puts it.
Two things fixed does not mean. It does not mean fee free: establishment and other fees sit alongside the rate, which is why the total amount payable is the comparison number. And it does not always mean flexible: some lenders charge an early repayment recovery amount if you clear a fixed loan ahead of schedule, so if paying off early is your plan, check that line on the offer before signing.
Most personal loans and car loans arranged through BorrowClub are fixed for the term, and every offer states the rate, the fees and the total payable together.