How is the South Africa bond monthly repayment calculated?

For a repayment bond, this tool uses the standard amortization formula: M = P [ i(1+i)^n ] / [ (1+i)^n - 1 ], where P is the loan amount (property price minus deposit), i is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (term in years multiplied by 12). This assumes a fixed rate for the full term.

What is the difference between repayment and interest-only?

A repayment bond pays down both interest and part of the loan balance each month, so the balance reaches zero at the end of the term. An interest-only bond pays just the interest each month, so the monthly cost is lower, but the full loan amount is still owed at the end of the term and must be settled separately, for example from savings or the sale of the property.

Does this calculator include transfer duty or bond registration costs?

No. This tool calculates the bond repayment on the loan amount only. Transfer duty, bond registration fees, and attorney costs are separate once-off costs paid on registration and depend on the property price and whether you qualify for any transfer duty exemption.

What bond term and interest rate should I use?

South African bonds commonly run for 20 or 30 years, with 20 years being the standard term offered by most banks. Interest rates are usually quoted as prime rate plus or minus a percentage, and vary by lender, deposit size, and credit profile, so use the rate quoted on your specific bond offer or a current prime-linked rate for the most accurate estimate.

Why does a larger deposit lower my monthly repayment?

A larger deposit reduces the loan amount you need to borrow, which directly lowers both the monthly repayment and the total interest charged over the term. A bigger deposit can also improve your loan-to-value ratio, which sometimes helps you qualify for a lower interest rate from the bank.

Can I use this calculator for any currency other than ZAR?

The figures are labeled in South African Rand (R), but the underlying math is currency-neutral. You can enter values in any currency and read the results in that same currency, since the calculation only depends on the numbers you enter, not the currency symbol.

South Africa Mortgage Calculator

Name: South Africa Mortgage Calculator
Availability: InStock
Author: Nham Vu

Enter your property price, deposit, interest rate, and loan term to see your monthly bond repayment, total interest, and a year-by-year repayment schedule in ZAR.

Bond Details

Property Price

Deposit 10.0%

Bond Term

Annual Interest Rate

Repayment Type

Repayment Interest-only

Monthly Bond Repayment

Live calculation

Monthly Repayment

R0.00

Loan Amount

Total Interest

Total Repaid

Payoff Date

—

Year	Annual Payment	Interest Paid	Principal Paid	Balance

Summary

Enter your property price, deposit, interest rate, and loan term to see your monthly bond repayment, total interest, and a year-by-year repayment schedule in ZAR.

How it works

Enter the property price and your deposit amount; the deposit percentage updates automatically.
Choose your bond term in years and enter the annual interest rate.
Select Repayment (capital and interest) or Interest-only.
Read the monthly repayment, total interest, and total repaid figures as you type.
Expand the repayment schedule for a year-by-year breakdown of interest, principal, and remaining balance.

Use cases

A first-time buyer comparing monthly repayments on a 20-year bond term versus a 30-year term at the same rate.
Someone switching bonds who wants to see how a higher deposit lowers the loan amount and monthly cost.
A buy-to-let investor comparing repayment versus interest-only monthly costs on the same loan.
Anyone checking how much total interest builds up over the full bond term before applying.
A buyer testing how a change in the prime lending rate affects the monthly repayment.
Someone budgeting for a new home who wants a quick estimate before visiting a bank or bond originator.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu