See how much your portfolio allocation has drifted from target when you do not rebalance. Enter initial value, target % stocks, returns, and years.
Asset Allocation Drift
See how much your portfolio allocation has drifted from your target when you do not rebalance. Enter initial value, target % in stocks (rest in bonds), and returns over the period.
Understanding Allocation Drift
Why your allocation moves when you do not rebalance
Target allocation
Your intended mix (e.g. 60% stocks, 40% bonds). You start with the portfolio split according to these weights.
Stocks % + bonds % = 100%.
Each sleeve grows at its own return; no rebalancing.
Higher-return asset becomes a larger share over time.
Drift = current % − target % (in percentage points).
Rebalancing
Selling the overweight asset and buying the underweight one to restore target weights. Reduces drift and can manage risk.
Typical bands: rebalance when drift exceeds 5% or 10%.
Or rebalance on a schedule (e.g. annually, quarterly).
In taxable accounts, rebalancing can create capital gains.
Use Rebalancing Frequency Impact to compare schedules.
No rebalancing is applied; each sleeve compounds at its own return. The higher-return sleeve grows faster, so its share of the portfolio increases and allocation drifts.
A common rule of thumb is to rebalance when drift exceeds 5 percentage points (e.g. 60/40 target becomes 65/35 or 55/45). This calculator shows the exact drift for your inputs.
Asset Allocation Drift: How Much Has Your Portfolio Drifted From Target?
When you hold a target allocation (e.g. 60% stocks, 40% bonds) and do not rebalance, the asset that performs better becomes a larger share of the portfolio. This calculator shows how much your allocation has drifted in percentage points and the resulting portfolio value.
Allocation drift is the change in your portfolio's actual weights compared with your target. If your target is 60% stocks and 40% bonds and you do not rebalance, and stocks outperform bonds, the stock sleeve grows faster and your actual allocation shifts toward stocks (e.g. 70% stocks, 30% bonds). The drift in stocks is +10 percentage points.
Why Drift Happens
Each asset compounds at its own return. The higher-return asset increases in value more, so its share of the total portfolio rises. Without rebalancing, there is no mechanism to bring weights back to target.
Measuring Drift
Drift is measured in percentage points (pp). Current % stocks − target % stocks = drift in stocks. Positive drift means you are overweight stocks; negative drift means you are underweight stocks (overweight bonds).
How It Is Calculated
Start with initial portfolio value and target weights. Value in stocks = initial × (target % stocks) × (1 + r_stocks)^years. Value in bonds = initial × (target % bonds) × (1 + r_bonds)^years. Total = value stocks + value bonds. Current % stocks = value stocks ÷ total × 100. Drift = current % stocks − target % stocks (in pp).
No Rebalancing
The calculator assumes you do not rebalance over the period. So each sleeve grows independently. For the effect of rebalancing on terminal value, use the Rebalancing Frequency Impact calculator.
Why It Matters
Large drift can push your portfolio toward more risk (if stocks drift up) or less return (if bonds drift up). Many investors rebalance when drift exceeds a band (e.g. 5% or 10%) to keep risk and return in line with their plan.
When to Rebalance
Rebalance when drift exceeds your chosen band, or on a schedule (e.g. annually). In taxable accounts, rebalancing can trigger capital gains; consider rebalancing in IRAs or 401(k)s first.
Drift and Risk
Large drift toward stocks increases equity risk; large drift toward bonds may reduce expected return. Use this calculator to see how far you have drifted and whether you are still within your risk tolerance before deciding to rebalance.
Using This Calculator
Enter initial portfolio value, target % in stocks (bonds = 100 − stocks), annual return for stocks (%), annual return for bonds (%), and years without rebalancing. The calculator shows current allocation, drift in percentage points, and portfolio value.
What to Enter
Use historical or expected returns for the two sleeves. Years = how long you have not rebalanced. For a quick check, use 1 year and your last year's returns.
Sensitivity to Return Difference
The larger the gap between stock and bond returns, the faster allocation drifts. A 60/40 portfolio with stocks at 10% and bonds at 2% will drift more over 5 years than one with stocks at 6% and bonds at 4%. Use the calculator with different return assumptions to see how drift changes.
Conclusion
Allocation drift shows how far your portfolio has moved from your target when you do not rebalance. This calculator gives the exact drift in percentage points and the resulting portfolio value. Use it to decide when to rebalance and to understand how returns have shifted your allocation.
Combine it with the Rebalancing Frequency Impact calculator to see how different rebalancing schedules affect terminal value and to choose a rebalancing strategy that fits your goals and tax situation.
In summary: allocation drift is the change in your actual weights from target when you do not rebalance. This calculator gives the exact drift in percentage points and portfolio value so you can decide when to rebalance and stay within your risk tolerance.
Frequently Asked Questions
Common questions about allocation drift
What is allocation drift?
Allocation drift is how much your actual portfolio weights have moved from your target. If you target 60% stocks and end up with 70% stocks (without rebalancing), drift in stocks is +10 percentage points.
How is drift calculated?
Start with initial value and target weights. Grow each sleeve at its return for the given years (no rebalancing). Current % stocks = value stocks ÷ total × 100. Drift = current % stocks − target % stocks (in pp).
Why does drift happen?
The asset with the higher return grows faster, so its share of the portfolio increases. Without rebalancing, weights drift away from the target.
When should I rebalance?
Many investors rebalance when drift exceeds 5% or 10% (e.g. 60/40 becomes 65/35 or 55/45), or on a schedule (e.g. annually). Use this calculator to see your current drift.
Does rebalancing improve returns?
It can go either way. Rebalancing can add a "rebalancing bonus" in certain return patterns (mean reversion) or a "cost" in strong trends. Use the Rebalancing Frequency Impact calculator to compare.
What if I have more than two assets?
This calculator uses two assets (stocks and bonds). For multiple assets, drift is computed per asset: current % − target % for each. The same logic applies.
What return should I use?
Use historical returns for the period you are analyzing, or expected long-term returns for planning. Real returns vary; the calculator shows drift under your assumed returns.
Does this account for taxes?
No. The calculator does not model taxes. Rebalancing in taxable accounts can trigger capital gains; consider tax-advantaged accounts for rebalancing when possible.
How does this relate to Rebalancing Frequency Impact?
This calculator shows how much you have drifted without rebalancing. The Rebalancing Frequency Impact calculator shows how often to rebalance and the effect on terminal value (rebalancing bonus or cost).
Who should use this calculator?
Anyone with a target allocation (e.g. 60/40) who wants to see how much their portfolio has drifted after a period without rebalancing, and to decide whether to rebalance now.
What is a typical rebalancing band?
Many investors use a 5% or 10% band: rebalance when any asset drifts more than 5 or 10 percentage points from target (e.g. 60/40 becomes 65/35 or 55/45). This calculator shows your exact drift so you can compare with your band.
Usage of this Calculator
Practical applications
Who Should Use This Calculator?
Long-Term Investors With Target AllocationsTo see how much your 60/40 or similar portfolio has drifted after a few years without rebalancing.
Advisors & EducatorsTo show clients the mechanics of drift and when rebalancing may be needed.
Retirement & Taxable Account HoldersTo check drift before deciding to rebalance (and where—e.g. in IRA first to avoid taxes).
DIY Portfolio ManagersTo quantify drift and compare with a 5% or 10% band before rebalancing.
Limitations
Two assets: Assumes stocks and bonds only. For multi-asset, compute drift per asset.
Constant returns: Assumes same return each year; real returns vary.
No contributions/withdrawals: Assumes no new money or withdrawals during the period.
No taxes: Does not model tax impact of rebalancing.
Bonds = 100 − stocks: Only two assets; target % bonds is implied. For three or more assets, compute drift per asset separately.
Real-World Examples
Example: $100k, 60/40, stocks 8%, bonds 3%, 5 years
Stocks: $60k × 1.08^5 ≈ $88.1k. Bonds: $40k × 1.03^5 ≈ $46.4k. Total ≈ $134.5k. Current % stocks ≈ 65.5%. Drift ≈ +5.5 pp. Consider rebalancing.
Example: $200k, 50/50, stocks 10%, bonds 2%, 10 years
Stocks grow much faster. After 10 years, allocation can drift to roughly 70/30. Drift in stocks ≈ +20 pp. Strong case for rebalancing to restore target.
Example: 1 year, similar returns
If stocks and bonds have similar returns in a given year, drift is small. Use the calculator with 1 year and your actual returns to check.
Summary
Quick recap
This calculator shows how much your portfolio allocation has drifted from your target when you do not rebalance. You enter initial value, target % stocks (bonds = rest), returns for stocks and bonds, and years. It reports current allocation, drift in percentage points, and portfolio value. Use it to decide when to rebalance and to understand how returns have shifted your allocation. Pair it with the Rebalancing Frequency Impact calculator to see how rebalancing frequency affects terminal value. A common rule is to rebalance when drift exceeds 5% or 10%; this tool gives you the exact drift for your inputs so you can stay within your risk band.
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See how much your portfolio allocation has drifted from target when you do not rebalance. Enter initial value, target % stocks, returns, and years.
How to use Asset Allocation Drift Calculator
Step-by-step guide to using the Asset Allocation Drift Calculator:
Enter your values. Input the required values in the calculator form
Calculate. The calculator will automatically compute and display your results
Review results. Review the calculated results and any additional information provided
Frequently asked questions
How do I use the Asset Allocation Drift Calculator?
Simply enter your values in the input fields and the calculator will automatically compute the results. The Asset Allocation Drift Calculator is designed to be user-friendly and provide instant calculations.
Is the Asset Allocation Drift Calculator free to use?
Yes, the Asset Allocation Drift Calculator is completely free to use. No registration or payment is required.
Can I use this calculator on mobile devices?
Yes, the Asset Allocation Drift Calculator is fully responsive and works perfectly on mobile phones, tablets, and desktop computers.
Are the results from Asset Allocation Drift Calculator accurate?
Yes, our calculators use standard formulas and are regularly tested for accuracy. However, results should be used for informational purposes and not as a substitute for professional advice.