How loan repayments are calculated in South Africa
The maths lenders use is simpler than the marketing around it. Understand the annuity formula and you'll never be surprised by an instalment again.
The annuity formula, in plain language
Your monthly instalment is calculated so the loan repays itself in equal payments over the term. each payment covers that month's interest plus a slice of the principal. Early payments are mostly interest; later payments are mostly principal. This calculator applies exactly that formula: amount, term and rate in; monthly instalment, total repayment and total interest out.
What rate to enter
The legal ceiling for unsecured credit is the repo rate + 21% per year. Where you land below that depends on your profile: strong files with stable income price near prime plus a margin; weaker files approach the cap. If you have a real quote, use its rate. If you're planning, 20 to 25% is a realistic planning band for mid-tier profiles; adjust and watch how sensitive the instalment is.
What this calculator leaves out
Initiation fees (once-off, regulated) and monthly service fees (capped at R69) are excluded. add roughly R165 + 10% of the amount once, plus R69 per month, for a full picture. Credit life insurance, sometimes bundled into contracts, adds more; you're entitled to shop for your own policy instead.
The two numbers that should drive your decision
Monthly instalment decides whether you can afford the loan. Total repayment decides whether you should. A R50,000 loan over 84 months is R430/month cheaper than over 48. and costs about R23,000 more overall. When the two numbers disagree, total repayment is the one telling the truth.