What is rand cost averaging?
Rand cost averaging is investing a fixed amount at fixed intervals — say R1,000 on the 1st of every month — regardless of what markets are doing. The fixed rand amount automatically buys more units when prices are low and fewer when they're high.
That mechanical tilt produces a small piece of arithmetic magic: across the period, the average cost per unit lands below the average price per unit. And in practice, it's simply how a debit-order investment already works.
The mechanics
No forecasting is involved. When the unit price drops, R1,000 stretches to more units; when it rises, the same R1,000 buys fewer. The buying leans towards cheap months entirely by itself — the volatility everyone fears is exactly what the method feeds on.
The arithmetic, worked out
Take R1,000 a month for three months, at illustrative unit prices:
- Month 1 — price R10: R1,000 buys 100 units
- Month 2 — price R8: R1,000 buys 125 units
- Month 3 — price R12.50: R1,000 buys 80 units
Three months, R3,000 in, 305 units out. Average cost: R3,000 ÷ 305 = R9.84 per unit. Average price over the period: (R10 + R8 + R12.50) ÷ 3 = R10.17.
The average cost sits below the average price — not through clever timing, but because the fixed amount bought hardest in the cheapest month. The prices are made up; the arithmetic holds for any prices that move around.
Why a debit order is the whole strategy
The deeper value is behavioural. A monthly debit order removes the question "is today a good day to invest?" — a question that keeps money parked on the sidelines waiting for a perfect moment that is only visible in hindsight. The decision is made once, then the system executes it every month without a mood.
The honest caveat
In a market that rises steadily, a lump sum invested at the start ends ahead of the same money drip-fed in — more of it spent more time invested and compounding. Rand cost averaging is not a return-boosting trick; it's a way of smoothing the entry and automating the habit for money that arrives monthly anyway, which is how most salaries work.
The lever that actually dominates is time in the market. "What does starting 10 years earlier actually do? (compound growth)" works that one out.
Terms used on this page
- volatility
- How much and how quickly an investment's price swings up and down. Higher volatility means a rougher ride along the way — not necessarily a different destination.
- compounding
- Growth on growth: returns earn their own returns. It is why time in the market matters more than the size of any single deposit.
Reviewed July 2026