Portfolio Rebalancing Calculator
Work out exactly what to buy and sell to return to your target allocation.
Please note: For information only, not investment advice. Projections assume constant rates; real markets fluctuate and capital is at risk.
What the Portfolio Rebalancing Calculator does
Rebalancing restores your target weights by trimming what has grown and topping up what has lagged. It enforces buying low and selling high mechanically — but it also triggers taxable events, which is why adding new money to the underweight positions is usually the better route.
Formula
New total = Current total + New moneyTarget value = New total × Target % ÷ 100Action = Target value − Current value
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Current value of each holding | text | Yes | Separate values with commas, spaces or new lines. |
| Target allocation (%) | text | Yes | Separate values with commas, spaces or new lines. |
| New money to invest | selected currency | Optional | Rebalance by adding rather than selling. Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Currency.
- Enter Current value of each holding and Target allocation (%).
- Optionally add New money to invest.
- Select Calculate.
Worked example
Holdings of $52,000, $28,000, $12,000 and $8,000 drifted from 45/30/15/10 targets.
- Values
- 52000, 28000, 12000, 8000
- Targets
- 45, 30, 15, 10
Total $100,000, so sell $7,000 of the first holding and buy across the others to restore the plan.
Frequently asked questions
How often should I rebalance?
Annually, or when drift exceeds a set band. Research generally finds frequent rebalancing adds cost without improving returns.
Does rebalancing improve returns?
Not reliably. Its real value is controlling risk — without it, the best performer eventually dominates the portfolio.
Method and sources
Method. The trades required to return each holding to its target weight, computed against the portfolio total including any new money added.
Assumptions
- Positions can be traded in the sizes indicated, and no minimum or fractional-share constraint intervenes.
- New money is available to be allocated as part of the same operation.
Limitations
- Costs are not modelled. Rebalancing incurs spreads, commissions and, in a taxable account, realised gains that can exceed the benefit of the correction.
- Directing new money to underweight holdings achieves much of the same effect without selling anything, and this calculator does not weigh that alternative.
- How often to rebalance is a judgement about cost against drift, not something the arithmetic answers.