When the Reserve Bank moves the repo rate, every linked loan you hold moves with it. Banks announce the change in percentage points, which tells you almost nothing useful. This calculator turns it into the number that actually matters: what your instalment becomes, and what the change costs you over what is left of the loan.
It works for any rate move, up or down. Fill in only the sections that apply to you.
This costs you
R0
more per month
How this is worked out
- Each loan is recalculated over its remaining term at the new rate, which is what your bank does when prime moves.
- Enter what you still owe, not what you originally borrowed. Using the original amount overstates the impact.
- Only linked or variable-rate agreements move with prime. If yours is fixed, leave it out until the fixed period ends.
- The total over the remaining term assumes the new rate holds for the rest of the loan. It will not, because rates move. Treat it as a scale indicator, not a forecast.
- Fuel is the price change times litres times fills. It excludes the knock-on effect on food and delivery prices, which is real but arrives later.
Where to find your numbers
- Outstanding balance — on your latest bond or vehicle finance statement, not the original purchase price.
- Years or months left — the remaining term, which is shorter than the term you signed for.
- Current rate — your statement shows it. Most South African bonds are linked to prime, often quoted as prime plus or minus a margin.
What to do with the answer
If the rate went up and the new figure fits, adjust your debit order now rather than discovering the shortfall on the day it bounces. A single missed payment is recorded on your credit record and follows you for years, raising the rate on everything you borrow afterwards.
If the rate came down, the strongest move is to leave your debit order exactly where it is. The whole saving then goes against the capital, and on a bond that typically cuts years off the term.
If it does not fit, the problem is affordability rather than the rate. If you want the mechanism behind all of this — repo versus prime, which debts reprice and which do not — read how interest rate changes affect what you pay. To check what you can carry overall, use the affordability calculator, and read what the September 2026 rate and fuel increases mean for the rest of your budget.
Prime is 10.75% from 25 September 2026, following the Reserve Bank’s 0.25 percentage point repo increase to 7.25%. This calculator assumes a standard amortising loan and does not include monthly service fees or insurance, which do not change when the rate moves.