Portfolio Rebalance Calculator
Free Portfolio rebalance Calculator for investing. Enter your numbers to see returns, costs, and optimized scenarios instantly.
Reviewed by Sahil, Senior Finance & Tax Editor
Formula
Trade = Target Value - Current Value; Target Value = Total Portfolio x Target %
For each asset class, the target dollar value is calculated by multiplying the total portfolio value by the target percentage. The difference between target and current values determines whether you need to buy or sell that asset.
Worked Examples
Example 1: Growth Portfolio Rebalance
Problem:A $100,000 portfolio has drifted to 70% stocks, 20% bonds, 10% cash. Target allocation is 60/30/10. What trades are needed?
Solution:Current: Stocks $70,000 (70%), Bonds $20,000 (20%), Cash $10,000 (10%)\nTarget: Stocks $60,000 (60%), Bonds $30,000 (30%), Cash $10,000 (10%)\nTrades: Sell $10,000 stocks, Buy $10,000 bonds, Cash unchanged\nPortfolio drift = (|70-60| + |20-30| + |10-10|) / 2 = 10%
Result:Sell $10,000 in stocks and buy $10,000 in bonds. Turnover: 10%.
Example 2: Conservative Rebalance After Market Drop
Problem:A $80,000 portfolio is now 45% stocks, 40% bonds, 15% cash. Target is 50/40/10.
Solution:Current: Stocks $36,000 (45%), Bonds $32,000 (40%), Cash $12,000 (15%)\nTarget: Stocks $40,000 (50%), Bonds $32,000 (40%), Cash $8,000 (10%)\nTrades: Buy $4,000 stocks, Bonds unchanged, Sell $4,000 cash\nPortfolio drift = (|45-50| + |40-40| + |15-10|) / 2 = 5%
Result:Move $4,000 from cash to stocks. Turnover: 5%.
Frequently Asked Questions
What is portfolio rebalancing and why is it important?
Portfolio rebalancing is the process of realigning the weightings of assets in your portfolio back to your original target allocation. Over time, different assets grow at different rates, causing your portfolio to drift from its intended risk profile. For example, if stocks outperform bonds over a year, your portfolio may become overweight in stocks and thus riskier than planned. Rebalancing forces you to sell high-performing assets and buy underperforming ones, which is a disciplined form of buying low and selling high. This helps maintain your desired risk level and can improve long-term risk-adjusted returns.
How often should I rebalance my portfolio?
There are several common rebalancing strategies. Calendar-based rebalancing involves checking and adjusting your portfolio at regular intervals such as quarterly, semi-annually, or annually. Threshold-based rebalancing triggers action only when an asset class drifts beyond a certain percentage from its target, commonly 5 percent. A hybrid approach combines both methods, checking at regular intervals but only acting if drift exceeds the threshold. Research suggests that annual or semi-annual rebalancing tends to be optimal for most investors because it balances the benefits of maintaining your target allocation against the transaction costs of frequent trading.
What is portfolio drift and how is it measured?
Portfolio drift measures how far your current asset allocation has moved from your target allocation. It is calculated by summing the absolute differences between current and target percentages for each asset class and dividing by two to avoid double counting. A drift of zero means your portfolio perfectly matches your target. A drift above 5 percent is generally considered significant enough to warrant rebalancing. Higher drift indicates greater deviation from your intended risk profile. Monitoring drift regularly helps you decide when rebalancing is necessary rather than relying solely on a fixed schedule, which may result in unnecessary trades when drift is minimal.
Should I rebalance using percentage or band-based thresholds?
Band-based thresholds are generally more efficient than fixed calendar rebalancing. With percentage bands, you set an acceptable range around each target allocation. For example, if your stock target is 60 percent, you might set bands of plus or minus 5 percent, meaning you only rebalance when stocks exceed 65 percent or drop below 55 percent. Wider bands reduce transaction costs and tax events but allow more drift. Narrower bands keep you closer to your target but increase trading frequency. Research from Vanguard suggests that a 5 percent threshold with semi-annual monitoring provides a good balance between maintaining risk targets and minimizing costs for most investors.
References
Reviewed by Sahil, Senior Finance & Tax Editor · Editorial policy