The inflation-adjusted real value and return of an investment over time.
Real value (today's rands)
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Nominal value
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Real return rate
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The illusion of a big number
An investment statement that shows R4 million after twenty years feels like wealth. The uncomfortable truth is that the R4 million will not buy what R4 million buys today, because inflation quietly erodes the purchasing power of every rand along the way. This calculator strips that illusion out. It takes your nominal growth, the headline number your fund reports, and converts it into a real value expressed in today's rands, so you can see what your money will genuinely command at the till.
The formula, and why you cannot just subtract
A lot of people estimate real return by subtracting inflation from the nominal rate. That is close but slightly wrong, and the error compounds over decades. The correct relationship divides one plus the nominal rate by one plus inflation, then subtracts one. With an 11 percent nominal return and 5 percent inflation, simple subtraction suggests 6 percent, but the real return is actually about 5.71 percent. The growth and inflation figures here are your own assumptions, not tax rates to confirm with SARS, so the honest move is to test a range rather than trust one guess.
Nominal and real, side by side
Put R500,000 to work at 11 percent nominal growth, with inflation running at 5 percent, over 20 years. The tool tracks both the headline figure and the inflation adjusted figure.
| Measure | Rate used | Value after 20 years |
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The statement will proudly show R4.03 million, but in terms of what it can actually buy, you have about R1.52 million in today's money. The other R2.5 million of the headline figure is simply inflation keeping pace, not real enrichment. That gap is why retirement plans built on nominal numbers so often disappoint.
Where tax sneaks into the picture
Real return measures purchasing power, but it does not account for tax, and tax is the third drag on any non sheltered investment. Interest above the annual exemption is taxed at your marginal rate, capital gains face a 40 percent inclusion rate for individuals, and dividends carry a 20 percent dividends tax. Those are the SARS figures to confirm, and they mean your after tax real return can be lower still. The practical defence is to use tax sheltered wrappers where you can, since growth that escapes tax keeps more of its real value intact.
A planning tip and a common error
The common error is celebrating a high nominal return without checking the inflation that produced it. In a high inflation environment, double digit returns can still leave you treading water in real terms. A practical tip: when you set a retirement target, set it in today's rands and use the real value output, not the nominal one, so your goal already accounts for the erosion. This is for anyone projecting long term savings, comparing investments, or sanity checking whether their portfolio is actually building wealth.
What inflation rate should I use?
There is no single right answer, which is why it is an input. South African inflation has moved around over the years, so a sensible approach is to run the calculator at a couple of rates, perhaps a lower and a higher one, and see how sensitive your result is. If the answer swings wildly between them, your plan is fragile to inflation and worth firming up.
Why is the real value still much larger than what I started with?
Because a positive real return means your money is genuinely outpacing inflation, just by less than the headline suggests. Growing R500,000 to R1.52 million in real terms is real wealth creation, it is simply far less dramatic than the R4.03 million nominal figure implies. If your real return were zero, the real value would equal your starting amount, and if it were negative, you would end up poorer in purchasing power than you began.