Bond Calculator
Work out your monthly SA home loan repayment at any interest rate and term. Set the property price, deposit, and rate; the calculator shows your monthly instalment, total interest paid over the life of the loan, and how the outstanding balance shrinks year by year.
Purchase price of the property — what the deed of sale says.
10% of home price · 10–20% is the SA norm.
Currently prime + 1% (SA prime is 10.25%, May 2026). Banks typically offer prime − 0.5% to prime + 1.5%.
20 years is the SA default. Longer term = lower monthly, far more interest paid over time.
Monthly bond repayment
R 14 165
on a R 1 350 000 bond over 20 years at 11.25%
Loan amount
R 1 350 000
R 1 500 000 − R 150 000 deposit
Total interest
R 2 049 589
152% of loan
Total repayment
R 3 399 589
over 240 months
Outstanding balance over time
Repayment uses the standard amortisation formula. Most SA bonds are variable-rate — your actual instalment will rise or fall when SARB changes the repo rate. This calculator does not include monthly bond admin fees (~R69/mo at most banks) or once-off bond initiation costs (~R6,000) — see the affordability calculator to find your maximum bond before you start house-hunting.
Compare by bank
Same calculator, pre-filled with each provider's typical mid-market rate. Useful when shopping a specific bank.
Data: SARB repo rate · National Credit Act 34 of 2005 · See methodology
How an SA bond repayment works
An SA home loan is a fully-amortising annuity: you pay the same fixed instalment every month for the life of the bond, but the split between interest and principal shifts dramatically over time. Early on, almost all of each payment is interest because the outstanding balance is large; near the end, almost all of each payment is principal because the balance has shrunk and there's little left to charge interest on.
The formula is M = P × [i(1+i)ⁿ] / [(1+i)ⁿ − 1], where P is the loan amount, i is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. SA banks use this formula identically regardless of which bank you pick — what differs between FNB, Standard Bank, Absa, Nedbank and Ooba is only the interest rate they offer you.
Most SA bonds are variable-rate, meaning your instalment changes when SARB changes the repo rate. A 1% rate hike on a R1.5m bond at 20 years adds about R1,000/month to your repayment. SARB's MPC meets six times a year — the next move is the variable that dominates your bond cost over the medium term.
Common SA bond scenarios at a glance
Six worked examples covering typical SA home prices and loan structures. All assume 11.25% (prime + 1%) over 20 years unless stated. Type the same numbers into the calculator above to verify.
R1.5m home, 10% deposit
11.25% over 20 years — typical first-time buyer
Median SA suburb home with the typical 10% deposit.
R2m home, 20% deposit
10.75% (prime +0.5%) over 20 years
Strong buyer profile gets a discount on the rate.
R800k home, 5% deposit
11.25% over 20 years — entry-level
Affordable bracket. R760k loan from a R40k deposit.
R3m home, 15% deposit
11.25% over 20 years
Upper-middle bracket. Note the R3.87m of pure interest.
R1m home, no deposit
11.75% (prime +1.5%) over 20 years — 100% bond
Zero-deposit bond — banks add a spread for the risk.
R1.5m home, 30-year term
11.25% over 30 years (vs 20yr above)
Saves R1k/month vs 20yr but adds R1.32m of interest.
Frequently asked questions
How is a bond repayment calculated in South Africa?
SA bonds use the standard amortisation formula: M = P × [i(1+i)ⁿ] / [(1+i)ⁿ − 1], where P is the loan amount, i is the monthly interest rate (annual ÷ 12), and n is the total number of monthly payments (years × 12). Each month's payment covers the interest accrued on the outstanding balance, with the remainder reducing the principal. In year 1 of a 20-year bond at 11.25%, roughly 80% of every instalment is pure interest — only 20% reduces what you owe. By year 18 those proportions invert.
What interest rate should I use?
Default to your bank's actual quote if you have one. If not, use SA prime (currently 10.25%, May 2026) plus a spread reflecting your profile: prime − 0.5% to prime − 1% if you're a top-tier earner with a 20%+ deposit, prime to prime + 0.5% for the average buyer with 10% deposit, prime + 1% to prime + 2% for first-time buyers with no deposit or weaker credit. The default in this calculator (prime + 1% = 11.25%) reflects what most middle-income SA buyers actually get offered.
What is the prime lending rate in South Africa?
Prime is the benchmark rate that SA banks offer their lowest-risk customers. As of May 2026 it is 10.25%, made up of the SARB repo rate (6.75%) plus a fixed 3.50% bank margin. SARB's Monetary Policy Committee meets six times a year and adjusts repo to manage inflation; prime moves in lockstep. SARB published a consultation paper in February 2026 proposing to phase out prime entirely in favour of direct repo-rate referencing — that change has no confirmed timeline yet.
How much deposit do I need for a home loan?
SA banks routinely offer 100% bonds (zero deposit) to qualifying buyers, but a 10% deposit gets you a noticeably better interest rate — usually around 0.5% lower over the life of the loan. A 20% deposit is the sweet spot: you avoid mortgage insurance, qualify for the best rates, and have meaningful equity from day one. First-time buyers under R3.5m income may also qualify for a First Home Finance subsidy (formerly FLISP) of R30,000–R130,000 from the Department of Human Settlements.
Is a 20-year or 30-year bond better in South Africa?
Almost always 20 years if you can afford the higher monthly. Compare a R1.5m bond at 11.25%: 20-year monthly is R15,739 with R2.27m total interest. 30-year monthly drops to R14,569 (only R1,170/month less) but total interest balloons to R3.74m — you pay R1.47m more for that small monthly saving. The 30-year option only makes sense if you genuinely cannot afford the 20-year payment AND you plan to make extra capital payments early to shorten the effective term.
What other costs are there besides the monthly bond?
On top of the monthly bond instalment, budget for: (1) Monthly bond admin fee — about R69 at most banks. (2) Building insurance — required by the bank, typically R200–R600/month depending on home value. (3) Levies if it's a sectional-title or estate property — varies hugely. (4) Rates and taxes payable to the municipality — usually 0.6–1% of the property value annually. (5) Once-off costs at registration: bond initiation fee (~R6,000), bond registration attorney fees, transfer duty (only on properties above R1.21m), and transfer attorney fees. Total once-off costs are typically 8–12% of the home price.
How do I qualify for a bigger bond?
Banks size your bond against gross monthly income using the National Credit Act affordability rules: total bond instalment must be ≤ 30% of gross monthly income, and your total monthly debt (bond + car + cards + personal loans) must be ≤ 36%. To qualify for more: increase income (the obvious one), pay down existing debt before applying, save a bigger deposit (a 20% deposit on a R2m home reduces the bond to R1.6m, lowering the required monthly), apply jointly with a partner (combined incomes), or buy in a lower price bracket. Use our affordability calculator to see your max bond at current rates.
Should I make extra payments on my bond?
Yes — bond extra payments are one of the highest-return uses of cash in SA. Every extra rand goes directly to capital, saving you all the interest that rand would have accumulated over the remaining term. On a R1.5m bond at 11.25% over 20 years, paying just R1,000 extra per month from the start cuts the term to 16 years and saves you R570,000 in interest. The maths beats almost any tax-free investment because the 'return' is your bond rate (~11%) tax-free. Most banks let you withdraw access-bond payments later if you need the cash back.
Sources: Standard amortisation formula from financial mathematics. SA prime rate (10.25%) and repo rate (6.75%) sourced from SARB and Ooba, verified May 2026. Affordability ratios from National Credit Act Regulation 23A. Calculator is for planning only — your bank's actual offer depends on your income, deposit, credit score, and current market conditions. Not financial advice; consult a bond originator for a real quote.
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