How Are Loan Repayments Calculated?

The repayment of your loan will be calculated on the basis of the interest rate at which you took the loan. It also partially depends on whether you have taken a long term or a short term loan. Most long term loans charge a heavier rate of interest the short term loans as in short term loans you are required to make the repayment quickly. The original amount that you borrow is called "principal amount" and over it you have to interest.
Interest rate will be decided by your lender depending on the market condition and the amount that is being lent. Interest is generally taken on every month for example, 6% interest for 12 months. This means that you have to pay 6% of the principle amount each month for 12 months. So if the principle amount is 1000 pounds. By the end of 12 months, you'll have to repay 1000+(60*12)=1720 pounds.