Project, honestly
What money today becomes — and what it actually buys
Future value is the cornerstone of retirement and long- horizon planning. It answers: if I have X today, and I add Y per month, and it grows at Z% per year, what will I have at the end? And — the question most planners skip — what will that money actually buy?
The two future values
Every future-value figure has two versions, and confusing them is the most common SA retirement-planning mistake.
- Nominal future value — the Rand number your statement will show in 20 years. Big number. Feels great. Misleading.
- Real future value — that nominal number deflated by accumulated inflation, expressed in today’s purchasing power. Smaller number. Feels worse. The honest one.
On a 30-year horizon at 5% inflation, the nominal-to-real ratio is about 4.3×. R5m nominal in 30 years has the buying power of about R1.16m today. If your retirement plan targets R5m, you’re planning to retire on what R1.16m buys today — which for most SA households is not enough.
The compounding curve
Future value graphs into a curve, not a line. Year 1 is boring. Year 10 has noticeable growth. Years 20–30 is where the curve gets steep — interest on accumulated interest does the heavy lifting.
An example. R100,000 at 8% nominal:
- 10 years: ~R215,000 nominal. (Real, at 5% inflation: ~R132,000.)
- 20 years: ~R466,000 nominal. (Real: ~R176,000.)
- 30 years: ~R1,006,000 nominal. (Real: ~R233,000.)
The nominal figure goes 10×. The real figure goes 2.3×. Both are valid. The real figure is what matters for planning what you can actually do at the end.
Adding monthly contributions
Lump sum alone is rarely the realistic case. Most SA savers contribute month-by-month — to a TFSA, a retirement annuity, a unit trust. The calculator handles that via the optional monthly contribution field.
The annuity portion of the future value is calculated separately and added to the lump-sum growth. R500/month for 30 years at 8% becomes about R745,000 nominal. R100,000 lump sum PLUS R500/month for 30 years becomes about R1.75m nominal. The lump sum and the monthly do their work in parallel.
What rate to use
Three reasonable defaults for SA planning:
- Conservative — 7% nominal. Roughly what a balanced fund with heavy fixed-income tilt has historically returned.
- Balanced — 8–9% nominal. A 60/40 equity/bond mix historical average.
- Equity-heavy — 10–12% nominal. JSE long-term average, but with a wide year-to-year range.
Run multiple scenarios. If the conservative case still gets you to a respectable real future value, you’re probably saving enough. If only the optimistic case works, you’re relying on returns you may not get — save more.
The TFSA wrapper
In a Tax-Free Savings Account, every Rand of growth is tax-free for life — so the nominal future value here is also your after-tax figure. Annual and lifetime contribution limits apply (set by SARS, updated by gazette), and exceeding either incurs a penalty tax. For most South Africans, maxing the TFSA before contributing to a taxable account is the highest-return easy decision available. Inside an RA or pension fund, contributions are also tax- deductible up to limits, and growth is tax-deferred until withdrawal. Outside any wrapper, interest above the SARS exemption is taxable; capital gains and dividends each have their own rules.
The inflation honesty test
Before relying on a future value for planning, ask one question: what does it look like in today’s Rand?Enter the inflation field; check the real figure. If the real figure isn’t enough to meet the goal, the plan is short — even if the nominal looks comforting.