What the loan instalment calculator can do
This calculator works for comparing any bank offer, regardless of amount, term, or lender — use it for a short-term loan over a few months or a multi-year personal loan for a much larger sum.
It calculates the equal-instalment (annuity) variant, where every payment is the same size for the whole term. That's the most common repayment structure banks offer for personal loans.
How to calculate a loan instalment
You need three figures to work out the monthly instalment: the loan amount, the nominal interest rate, and the term. We explain each one below.
Loan amount
This is the sum you're applying for — the amount you'll actually receive (or that gets paid to a merchant, if you're financing a purchase). The calculator accepts any amount, so you can check the instalment for a small short-term loan or a much larger one.
Interest rate
A loan's interest rate is always quoted per year. If a bank offers a nominal rate of 10% a year, that's the figure you enter — the calculator converts it to a monthly rate automatically.
Keep in mind the nominal rate isn't the same as the APRC (annual percentage rate of charge). APRC also factors in the arrangement fee and other charges, so it's always higher. If your bank charges a fee, check our APRC calculator to see the real cost.
Loan term
You enter the term in months — the time you commit to repaying the full loan plus interest. A longer term lowers the monthly instalment but raises the total cost, since interest accrues for longer. A shorter term means a higher instalment but a lower overall cost.
Worked example
Say you borrow 20,000 at a nominal rate of 12% a year, over a 36-month term. The monthly rate works out to 12% ÷ 12 = 1%. Plugging that into the annuity formula gives an instalment of roughly 664 a month, with a total repayment of around 23,910 — meaning total interest of about 3,910.
