Portfolio Rebalancing Calculator

A portfolio drifts away from its targets automatically, because the holdings that perform become a larger share of the total. Left alone for long enough, an allocation chosen deliberately becomes one nobody chose.

This compares where each holding sits against where you want it and produces the adjustment for each. Enter a new contribution and it directs that money at the underweight positions first, which frequently restores the targets without selling anything.

Result

Largest drift

Equities

Largest drift: 8%
Current total: $100,000
Total after contribution: $100,000
Contribution: $0
Total to buy: $8,000
Total to sell: $8,000
Targets sum to: 100%
Targets check: Targets sum to 100%

This tool is for informational and educational purposes only. It is not financial or investment advice, and past performance does not guarantee future results.

Adding new money to the under-weight assets rebalances without selling, which avoids transaction costs and any tax event a sale would create.

Rebalancing is a discipline, not a return strategy. Set a drift threshold or a schedule and follow it.

Rebalancing plan

Asset	Current value	Current %	Target %	Target value	Buy / (sell)
Equities	$68,000	68%	60%	$60,000	-$8,000
Bonds	$18,000	18%	25%	$25,000	$7,000
Property	$9,000	9%	10%	$10,000	$1,000
Cash	$5,000	5%	5%	$5,000	$0

How to use the portfolio rebalancing calculator

Add one line per holding: name, current value, target percentage.
Enter any new money you are adding.
Read the adjustment column - positive to buy, negative to sell.
Check that your targets sum to 100 percent.

What people use this for

Working out the trades that restore a target allocation.
Directing a new contribution at the underweight holdings.
Checking how far a portfolio has drifted before deciding whether to act.
Preparing a rebalancing plan before placing orders.

Worked examples

Every figure below is produced by running this calculator against the example inputs, so the numbers always match the tool.

A drifted portfolio with no new money

Equities have run ahead of the target allocation.

Largest drift: Equities
Total to buy: $8,000
Total to sell: $8,000

Rebalancing with a contribution instead

The same portfolio with $12,000 added.

Largest drift: 8%
Total after contribution: $112,000
Total to sell: $800

Rebalancing with contributions is usually cheaper

Selling to rebalance generates transaction costs and, in a taxable account, realises gains. Directing new money at the underweight holdings achieves much of the same correction without either.

For anyone contributing regularly, this is frequently enough on its own, and the sell column here often comes out empty once a contribution is entered.

Drift is not automatically a problem

Small deviations from a target are normal and correcting them constantly costs more than it achieves. Most systematic approaches rebalance either on a schedule or when a holding moves beyond a threshold, rather than continuously.

The largest-drift figure is there to support that decision. Whether to act on it is a judgement this tool does not make.

Tax is the constraint this ignores

In a taxable account, selling to rebalance realises gains and creates a liability the calculation knows nothing about. That can easily exceed the benefit of a modest correction.

In a tax-advantaged account the constraint largely disappears, which is why rebalancing is often concentrated there. Neither situation is assumed here - the tool reports the trades and leaves the tax question where it belongs.

Methodology and assumptions

What this calculator does, and what it deliberately does not do.

Results are arithmetic on the numbers you enter. Nothing here predicts prices or connects to an exchange, broker or market data feed.
Nothing you type is transmitted or stored - the calculation runs entirely inside your browser.

This tool is for informational and educational purposes only and does not constitute financial or investment advice. Past performance does not guarantee future results.

Nothing on this website is a recommendation to buy, sell or hold any security, currency, derivative or digital asset. No price is predicted and no return is promised or implied.

Trading and investing carry the risk of substantial loss, including the loss of your entire capital. Leveraged products can produce losses that exceed your deposit. Tax treatment depends on your jurisdiction and your circumstances.

Frequently asked questions

How often should I rebalance?

This site does not suggest a frequency. Schedule-based and threshold-based approaches are both common, and the right answer depends on costs, taxes and the portfolio.

Do my targets have to sum to 100?

They are normalised if they do not, but a total other than 100 usually indicates an error worth checking.

Does this account for tax on sales?

No. Realised gains in a taxable account can outweigh the benefit of rebalancing, and that calculation is outside this tool.

Is this investment advice?

No. It calculates the trades your own targets imply, for informational and educational purposes only. It does not suggest an allocation.

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