Current mix
Measure before acting
Portfolio Rebalancing Calculator
Compare up to four portfolio holdings with target weights, test a drift band and separate contribution-only purchases from full trades.
Drift and rebalancing plan
Measure current drift first, then see how far new cash can restore the written target without sales.
Enter your figures, then press “Build the rebalancing plan” to calculate your result.
No result yetComplete the fields and use the calculation button.
What the multi-holding rebalancing calculator shows
This calculator measures up to four holdings against target percentages after adding new cash. It flags drift beyond a chosen band, allocates contribution-only purchases to underweight holdings and shows the full buy or sell amount needed for an exact rebalance.
- Target percentages should total 100 percent.
- Taxes, trading costs and account restrictions are not calculated.
- Contribution-only output avoids sales but may not restore every target exactly.
Rebalancing restores a rule
A drift calculation applies an existing target. It does not decide whether that target still fits the goal.
Written target
Use the existing policy range
Cash first
Direct contributions before considering sales
Validate the target before calculating trades
The four target percentages should total 100 percent. A holding can be unused by entering zero for both its value and target. If the targets do not total 100, the calculator stops and displays the difference instead of silently normalising a policy that may have been entered incorrectly.
Targets should come from a written allocation linked to the goal, withdrawal date and loss capacity. This tool applies a policy. It does not decide whether the policy remains suitable or predict which holding will perform best next.
Measure drift in percentage points and dollars
Current allocation divides each holding by the portfolio total. Target value multiplies the post-contribution total by the entered target percentage. Full-trade change is target value minus current value. A positive amount is a buy and a negative amount is a sale before taxes, fees and restrictions.
The band compares current percentage with target percentage. A five-point band around a 25 percent target triggers review below 20 or above 30 percent. A trigger does not automatically require a trade. It starts the documented decision process.
Use contributions before considering sales
The contribution-only plan directs new cash to underweight holdings in proportion to their dollar shortfalls. It never displays a sale. If available cash is enough to fill every shortfall, any remainder cannot restore the target without adding to already funded holdings or selling an overweight holding.
Compare the contribution-only result with the exact full-trade changes. In a taxable or restricted account, accepting some remaining drift may be preferable to an unnecessary sale. Across several accounts, apply location, tax and access rules before treating portfolio-level amounts as executable orders.
- Target percentages total 100
- Drift has crossed the written band
- Contribution cash is allocated first
- Trading and tax effects are reviewed
- The before and after allocation is recorded
Separate routine maintenance from a policy change
A rebalance restores an existing target. If the goal date, withdrawal needs, household risk or ability to tolerate loss changed, review the allocation itself before trading. Changing the target because one holding recently performed well is market timing, not maintenance.
Record the calculation date, values, targets, band, available contribution and chosen action. At the next review, this record shows whether the decision followed the policy and prevents a new rule from being invented after every market move.
Common questions about this calculator
Do I need to sell every time the allocation moves?
No. A written tolerance range can prevent unnecessary trades. New contributions may also move the portfolio closer to its target without selling.
What if my target percentages do not total 100?
Correct the policy inputs before acting. The calculator refuses to normalise them because that could hide an omitted holding or an incorrect target.