Portfolio Allocation Calculator
See current portfolio weights and the drift from 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 Allocation Calculator does
Allocation drift happens automatically: assets that outperform grow beyond their target weight, quietly raising risk. Measuring the drift tells you whether the portfolio still matches the plan you set.
Formula
Current weight = Holding ÷ Total × 100Drift = Current weight − Target weightEffective holdings = 1 ÷ Σ(weightᵢ²)
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Value of each holding | text | Yes | Separate values with commas, spaces or new lines. |
| Target allocation (%) | text | Yes | Must total 100. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Currency.
- Enter Value of each holding and Target allocation (%).
- Select Calculate.
Worked example
Holdings of $45,000, $30,000, $15,000 and $10,000 against 45/30/15/10 targets.
- Values
- 45000, 30000, 15000, 10000
- Targets
- 45, 30, 15, 10
Total $100,000 and every weight is exactly on target — no drift, no rebalancing needed.
Frequently asked questions
How much drift should I tolerate?
A five percentage point band is a common rule. Rebalancing more often raises costs and taxes without improving results much.
What is the effective holdings number?
The inverse Herfindahl index — how many equally weighted positions would give the same concentration. It exposes portfolios that look diversified but are not.
Method and sources
Method. Each holding as a percentage of total portfolio value, compared against the target weights entered.
Assumptions
- Valuations are current and on a consistent basis across holdings.
Limitations
- Allocation by value says nothing about risk. Two portfolios with identical weights can carry very different exposure if the holdings differ in volatility or correlate closely.
- Asset labels hide overlap — a global fund and a domestic one can hold the same companies, so the split on paper overstates the diversification actually held.