Portfolio rebalancing calculator

Compare current holdings with your target allocation. Calculate buys and sells, or allocate new money without selling, with a separate fee reserve.

Inputs

Hypothetical example. Replace these inputs with your own.

Rebalancing modeSell and buyContribute only

New cash contribution · USDCash set aside for costs · USD

Asset 1Asset label (optional)Current quantity · unitsPrice · USD/unitTarget weight · %

Find holding assetHolding asset (optional identity)

Select an identity to inspect stored references. Example numbers remain hypothetical until you explicitly apply values. Stored references are disabled on this site. Enter prices and supply manually.

Asset 2Asset label (optional)Current quantity · unitsPrice · USD/unitTarget weight · %

Find holding assetHolding asset (optional identity)

Select an identity to inspect stored references. Example numbers remain hypothetical until you explicitly apply values. Stored references are disabled on this site. Enter prices and supply manually.

Result

Calculation result

Example result

Starting holdings value: 1,000 USD
New cash contribution: 100 USD
Cash set aside as fee reserve: 10 USD
Modeled holdings after allocation: 1,090 USD
Total planned buys: 345 USD
Total planned sells: 255 USD
Largest absolute target drift: 0 percentage points

Estimates before exchange lot sizes and actual costs. The fee reserve remains outside modeled holdings as cash set aside, not an expense or a charged fee.
Targets are normalized to total 100%. Include cash as an asset row at price 1 if cash itself has a target weight. This is a one-time allocation plan, not a portfolio ledger, order or target recommendation.

Calculation breakdown
Asset	Current value · USD	Current weight · %	Normalized target weight · %	Target value · USD	Buy / sell value · USD	Units change · units	Final quantity · units	Final value · USD	Final weight · %	Target drift · percentage points
Asset A	800	80	50	545	-255	-2.55	5.45	545	50	0
Asset B	200	20	50	545	345	3.45	5.45	545	50	0

Saved scenarios

Save up to 20 new-tool scenarios on this device, separately from the six existing tools. Prices and balances stay out of the URL. DCA, journal and correlation scenarios save settings and a digest, requiring the matching CSV again to calculate.

Scenario nameSaved scenario

Saving requires browser storage and Web Locks.

Formula and worked example

Target holdings total = current portfolio + contribution − cash reserve. Full rebalancing buys or sells to each normalized target. Contribute-only allocates new investable cash in proportion to positive deficits, without selling. Reserve stays outside holdings and is not an assumed expense.

Hypothetical example: $800 in A and $200 in B, with $100 new cash and $10 reserve, leave $1,090 to allocate. At 50/50 targets, sell $255 of A and buy $345 of B. Contribute-only buys $90 of B and leaves weights about 73.3945%/26.6055%. Estimates exclude exchange lot sizes, actual costs and taxes.

These estimates use bounded decimal arithmetic. They are scenario calculations, not trading instructions or forecasts.

Methodology sources: Portfolio holdings and costs