Portfolio Rebalancing Calculator
Your current allocation against your target, the drift of each asset, and how much to buy or sell of each to rebalance, or how to spend new cash without selling.
Result…
How it's calculated
Current % = value ÷ total value Drift = current % − target % Buying and selling: trade = target % × (total + new cash) − current value Buying only: buy = max(0, target % × L − current value), with L chosen so the buys add up to the new cash
A portfolio drifts away from the mix you chose as some assets rise faster than others: a 50/40/10 split can become 60/30/10 after a good run for stocks. Rebalancing brings it back. With buying and selling, each asset moves to its target share of the total (plus any new money), so overweight assets are sold and underweight ones bought. With buying only, new cash goes to the most underweight assets first, topping them up to a common level, and nothing is sold, which avoids selling costs but may leave some drift if the cash is small. The page shows the current and target percentages, the drift in percentage points and the amount to trade for each asset.
Your numbers, step by step
About the Portfolio Rebalancing calculator
This portfolio rebalancing calculator compares what you hold with the mix you want and tells you what to buy or sell to get back to it. List your assets, what each is worth now and its target percentage, and it shows the current percentage of each, how far it has drifted from the target in percentage points, and the amount to trade. Choose “Buying and selling” to reach the targets exactly, or “Buying only (new cash)” to put new money into the most underweight assets without selling anything, which can avoid selling costs and tax on gains. A bar chart shows the mix now, the target and the result. It works with any assets and any currency, and every step is shown with your numbers. To see how a portfolio might grow over time, use the investment calculator.
How to use it
- Choose “Buying and selling” or “Buying only (new cash)”.
- Type the “Asset names (optional)” separated by commas.
- Enter the “Current values” and the “Target allocation % (same order)”, which must add up to 100.
- Add any “New cash to invest”, then read the buy or sell amount for each asset.
Worked example
A portfolio holds 78,000 in stocks, 32,000 in bonds and 10,000 in property, a total of 120,000, against targets of 60%, 30% and 10%. Stocks are at 65%, 5 points over target. Buying and selling: sell 6,000 of stocks, buy 4,000 of bonds and 2,000 of property. Buying only with 5,000 of new cash: buy 3,250 of bonds and 1,750 of property and sell nothing; stocks then make up 62.4% of 125,000, so 2.4 points of drift remain.
Updated
Questions people ask
How do I calculate how much to buy or sell to rebalance?
Multiply the total value of the portfolio, plus any new cash, by each asset's target percentage. The difference between that target value and what the asset is worth now is the amount to buy (positive) or sell (negative).
What is portfolio drift?
Drift is the gap between an asset's current share of the portfolio and its target, in percentage points. An asset that rises faster than the rest drifts above its target.
Can I rebalance without selling anything?
Yes, by directing new money to the assets that are below target. This calculator tops up the most underweight assets first. If the cash is not enough to reach every target, some drift is left, and the page shows how much.
How often should I rebalance my portfolio?
People use a fixed schedule, such as once a year, or rebalance only when drift passes a band they choose. Trading costs and tax on gains, which depend on your country and account, are reasons not to rebalance too often.
Does this calculator choose my target allocation?
No. It only works out the trades for the targets you enter. The right mix depends on your goals, time frame and attitude to risk, so ask a qualified financial adviser if you need help setting it.