How much must be bought or sold to restore a target allocation?
Rebalancing compares current asset values with target weights at the same total portfolio value. The output is a set of transfers around that total, so purchases and sales should offset before costs.
Comparing current value with target value
Enter total portfolio value, the current value of one holding, its target allocation and current share price. The calculator converts the target percentage into a target cash value and compares it with the current holding.
A positive difference and share result indicate an amount to buy; negative values indicate an amount to sell. Shares are not rounded, and the calculation assumes the rest of the portfolio value does not change during the rebalance.
Reading buy and sell differences
Positive differences indicate amounts to add and negative differences indicate amounts to reduce, following the output labels. Larger allocation drift produces larger suggested transfers.
Turning target weights into trade amounts
Target value = Portfolio value × (Target% ÷ 100)Difference = Target value − Holding valueShares to trade = Difference ÷ Share pricePositive means buy, negative means sell.Restoring an allocation without changing the total
The default allocation shows current amounts and desired percentages. The calculator converts each target weight into a target value and measures the trade required from the current value.
Targets, taxes and transaction constraints
Targets must describe a complete allocation. If target weights do not total 100%, the results do not represent a fully allocated portfolio.
- Portfolio value is unchanged while the rebalance is calculated.
- Every target is expressed as a percentage of the same total.
- Tax, spreads, fees, minimum trade sizes and new cash are excluded.
Calculations related to portfolio rebalancing
The following tools examine neighbouring parts of the same calculation without changing the inputs or assumptions used above.
Quick answers
Frequently asked questions
Why is the shares-to-trade result negative?
A negative result means the holding is above its target value, so the calculated difference represents shares to sell.
Does the calculator round to whole shares?
No. It divides the cash difference by share price and can return fractional shares.
Are taxes and transaction costs included?
No. Target value and shares to trade are calculated before tax, spreads and trading fees.
Educational content only. This guide is not financial advice.