Portfolio Rebalancing Calculator
Turn current holding values and target weights into a trade plan: drift per asset, the exact buy or sell amount, and a cash-only mode that never sells.
Holdings and targets
Trade plan
| Asset | Now | Now % | Target % | Drift | Action | After |
|---|---|---|---|---|---|---|
| US stocks | $60,000 | 60.00% | 60.00% | +0.00% | Hold | $60,000(60.0%) |
| International stocks | $18,000 | 18.00% | 20.00% | -2.00% | Buy $2,000 | $20,000(20.0%) |
| Bonds | $22,000 | 22.00% | 20.00% | +2.00% | Sell $2,000 | $20,000(20.0%) |
| Totals | $100,000 | 100.00% | 100.00% | — | Sell $2,000 · Buy $2,000 | $100,000 |
A full rebalance sells whatever is above target and buys whatever is below, bringing every drift to zero. In a taxable account, check the tax cost of the sells before you place them.
Drift is the current weight minus the target weight, and the trade for each asset is target value minus current value. Worked check: $60,000 of stocks and $40,000 of bonds against a 70/30 target with $10,000 of new cash puts the whole $10,000 into stocks, cutting the stock drift from −10.00% to −6.36% with no sales. Commissions, spreads and taxes are not modelled. Arithmetic only, not investment advice.
What is the Portfolio Rebalancing Calculator?
The ByteTools Portfolio Rebalancing Calculator takes what you hold today and what you want to hold, and produces the trades that get you there.
- Drift per asset shown as current weight minus target weight
- Exact buy or sell amount for every holding, with reconciling totals
- Cash-only mode allocates new money without selling anything
- Warns when target weights do not sum to 100% and scales them safely
- Post-trade weights and largest remaining drift at a glance
- Private by design — holdings never leave your browser
How to use the Portfolio Rebalancing Calculator
- 1
Pick a currency and choose between a full rebalance and a cash-only, never-sell plan.
- 2
In cash-only mode, enter the new money you have available to invest.
- 3
Add a row for each holding with its name, current value and target weight as a percentage.
- 4
Check the warning if your weights do not add up to 100%, and adjust them if that was not intentional.
- 5
Read the trade plan table for the buy or sell amount per asset and the resulting weights.
About the Portfolio Rebalancing Calculator
The ByteTools Portfolio Rebalancing Calculator takes what you hold today and what you want to hold, and produces the trades that get you there. For each asset it shows the current weight, the target weight, the drift between them and the exact amount to buy or sell, with totals that always reconcile back to your portfolio value.
There are two modes. A full rebalance sells whatever is above target and buys whatever is below, driving every drift to zero. Cash-only mode never sells: it directs new money to the holdings furthest below target, which shrinks the drift without triggering a taxable sale — usually the better option in a taxable account.
If your target weights do not add up to 100% the tool says so and scales them proportionally rather than silently producing nonsense. Everything is computed in your browser with nothing uploaded, and the output is arithmetic for planning, not investment advice.
Frequently asked questions
How do you calculate portfolio rebalancing?
Multiply your total portfolio value by each asset's target weight to get its target value, then subtract what you currently hold. A positive difference is an amount to buy and a negative one is an amount to sell.
What is portfolio drift?
Drift is how far an asset has wandered from its target, measured as its current weight minus its target weight. A 60% stock target that has grown to 68% has drifted by eight percentage points, which means more risk than you signed up for.
Can I rebalance without selling anything?
Yes, and this tool has a mode for it. Cash-only rebalancing sends every new contribution to whichever holdings are furthest below target. It is slower than selling but avoids capital gains tax, which usually makes it the better choice in a taxable account.
How often should you rebalance a portfolio?
Common approaches are once a year, or whenever any holding drifts more than five percentage points from its target. Rebalancing more often adds costs and taxes without much benefit, so a simple annual or threshold rule is usually enough.
Does the calculator account for taxes and trading fees?
No. It produces the raw trade amounts. Before placing sells in a taxable account, check the capital gains they would realise, and subtract any commission or spread from the amounts shown.
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