i What this calculator does
Quick answer: See how far each holding has drifted from its target weight and exactly what to buy or sell to bring the portfolio back into line. With the default inputs (local equity value 420 000, local equity target 40), it returns portfolio value of R880 000.00.
A portfolio drifts. What rises becomes a larger share of the total and what falls becomes a smaller one, so a plan set at 60/30/10 quietly becomes something else. Rebalancing sells what has grown and buys what has lagged, which is uncomfortable and is the point.
The research generally supports annual rebalancing or a threshold of about five percentage points of drift. More frequent rebalancing adds transaction costs and capital gains events without meaningfully reducing risk.
This calculator is for educational purposes only. Results are estimates and may vary depending on market conditions, spreads, commissions, platform settings, and exchange rates. It should not be considered financial advice.
How to use the Portfolio Rebalancing Calculator
It works immediately. Change one value, leave the others, and the difference belongs to that change.
- 1. Local Equity Value (R)
- 2. Local Equity Target (%)
- 3. Offshore Equity Value (R)
- 4. Offshore Equity Target (%)
- 5. Bonds and Cash Value (R)
- 6. Bonds and Cash Target (%)
The result panel reports:
- Portfolio Value Across the three buckets
- Largest Drift Against the threshold of
Alongside the headline figures, the calculator reports local equity, offshore equity, bonds and cash, targets total. Those are the numbers that usually explain why the headline result came out where it did.
Each stage of the arithmetic is set out under the answer, which means you can follow how it was reached.
See also: Asset Allocation Calculator.
Common results
What the calculator returns as the local equity value changes, with every other input at its default (local equity target 40, offshore equity value 310 000, offshore equity target 35, bonds and cash value 150 000, bonds and cash target 25, rebalancing threshold 5).
| Local Equity Value | Portfolio Value | Largest Drift | Turnover Required |
|---|---|---|---|
| R150 000 | R610 000.00 | 15.82% | R96 500.00 |
| R250 000 | R710 000.00 | 8.66% | R61 500.00 |
| R500 000 | R960 000.00 | 12.08% | R116 000.00 |
| R1 000 000 | R1 460 000.00 | 28.49% | R416 000.00 |
| R2 000 000 | R2 460 000.00 | 41.30% | R1 016 000.00 |
| R4 000 000 | R4 460 000.00 | 49.69% | R2 216 000.00 |
Figures used in this calculator
The South African constants this calculator relies on, with the page that holds the current value and the date it was last verified.
- Regulation 28 limits: 75% equities, 45% offshore for retirement funds. Source: Retirement Fund Contribution Limits (verified 27 September 2026).
- Offshore allowances: R2 million SDA, R10 million FIA a calendar year. Source: Exchange Control Allowances (verified 27 September 2026).
How the calculation works
The calculator takes seven inputs: Local Equity Value, Local Equity Target, Offshore Equity Value, Offshore Equity Target, Bonds and Cash Value, Bonds and Cash Target and Rebalancing Threshold. Rebalancing Threshold: Act only when drift exceeds this. The actual weight is holding value / total portfolio. The drift is actual weight - target weight. The trade is (total x target%) - current value. The act when is drift exceeds 5.0%. The breakdown also lists local equity sell, offshore equity sell, bonds and cash buy and total portfolio.
A worked example in rand
With the default inputs (local equity value R420 000, local equity target 40%, offshore equity value R310 000, offshore equity target 35%, bonds and cash value R150 000 and bonds and cash target 25%), the calculator returns a portfolio value of R880 000.00, across the three buckets. It also reports largest drift 7.95% and turnover required R70 000.00. Double the local equity value to 840 000 and the portfolio value moves from R880 000.00 to R1 300 000.00, the largest drift moves from 7.95% to 24.62% and the turnover required moves from R70 000.00 to R320 000.00.
How to read the result
With these inputs the calculator's own verdict reads: "2 of 3 holdings have drifted past the threshold. The largest drift is 8.0%." The verdict changes as the inputs cross the thresholds the calculator uses, and it is the fastest way to see which side of them you are on. Diversification is measured by how holdings move together in a crisis, not by how many there are; five JSE shares in the same sector are one position. The background to this calculation is in How Much of My Portfolio Should Be in Crypto?.
The South African angle
Three things change the picture for a South African trader using the portfolio rebalancing calculator. Regulation 28 limits a retirement fund to 75% in equities and 45% offshore, which is the allocation framework most South African pension money actually follows. Correlations that look low in calm years converged towards one in March 2020 for almost every asset class except government bonds and gold, which is the stress case a portfolio should be built for. Rebalancing a rand portfolio with offshore holdings is complicated by exchange control: moving money back into the local allocation is unrestricted, moving it out uses the annual allowance. The figures behind these points, and the ones the portfolio rebalancing calculator itself uses, are on the exchange control allowances reference.
Spotted an outdated figure? If a rate, limit or formula in this calculator no longer matches its source, email us the page and the source. A material correction is dated on the Updates Log.
Frequently asked questions
How often should I rebalance?
Annually, or when a holding drifts more than about five percentage points from its target. More frequent rebalancing adds brokerage and triggers capital gains without materially reducing risk. Less frequent lets the portfolio become something you did not choose.
Does rebalancing improve returns?
Not reliably. It controls risk, which is a different thing. Selling what has risen and buying what has fallen can add a little through the buy-low effect, but the honest case for it is that it keeps the portfolio matched to the risk you agreed to take.
What about capital gains tax?
Selling to rebalance in a taxable account triggers a disposal. Rebalancing with new contributions instead, by directing them to the underweight holding, avoids the event entirely and is usually the better route while you are still contributing.
Should I rebalance inside a tax-free savings account?
It is the easiest place to do it, because no capital gains arise. Note that a sale and repurchase inside a TFSA does not restore annual contribution room, so the trades themselves are free but the wrapper limits still apply.
Does Regulation 28 affect this?
Inside a retirement fund, yes: offshore exposure is capped at 45% and equities at 75%, so the targets must sit within those limits. A discretionary portfolio or a tax-free savings account has no such constraint.
What if my targets do not add to 100%?
The calculator says so rather than silently normalising them, because a target set that does not sum to 100% usually means something was mistyped rather than that a fourth bucket exists.
Want to embed this calculator on your site?
Embed this calculator
Free to use on your own site. Copy the code below and paste it where you want the calculator to appear.
<iframe src="https://www.tradeanswers.co.za/embed/portfolio-rebalancing-calculator.html"
width="100%" height="750" style="border:0;max-width:520px"
title="Risk Per Trade Calculator - TradeAnswers" loading="lazy"></iframe>
<p><a href="https://www.tradeanswers.co.za/portfolio-rebalancing-calculator.html">Portfolio Rebalancing Calculator</a> by <a href="https://www.tradeanswers.co.za/">TradeAnswers</a></p>