Calculator
Portfolio Rebalancing Calculator
Portfolio Rebalancing Calculator
Trades Required
US Stocks: −$5,000 · Bonds: +$3,000 · Cash: +$2,000
Rebalancing Analysis
Drift exists but no position is off target by as much as your 5% rebalancing band — you could wait. If you rebalance now, trading about $5,000 (3.3% of the portfolio) locks the allocation back down.
*Assumes current values are market values and targets are percentages of the total. Does not account for taxes on gains, transaction costs, or fund minimums. Educational only, not investment advice.
Getting Back to the Portfolio You Actually Chose
You pick an asset allocation — say 60% stocks and 40% bonds — for the risk you are willing to take. Then the market does its thing: stocks rally for two years and your portfolio quietly drifts to 70% equity. You have not changed your mind about risk, but your portfolio has. Rebalancing is the discipline of selling what grew and buying what lagged to restore the original mix. It is one of the few genuine free lunches in portfolio management, because it forces you to buy low and sell high mechanically, and it keeps a bad year in your overweighted asset from doing permanent damage to the plan. The catch is that rebalancing by intuition is a mess. Figuring out exactly how many dollars to move across four or five holdings, whether to sell winners or point new contributions at the laggards, and whether the drift is even worth acting on — that is arithmetic, and it is exactly what this calculator does. Most target-date funds rebalance automatically; everyone holding separate funds in a 401(k), IRA, or brokerage account has to do it themselves.
Target Value Minus Current Value
For each asset the math is a single line: trade = (target % ÷ total targets) × total portfolio value − current value. A positive result means buy; a negative result means sell. Targets are normalized against their own sum, so a set that totals 90 or 110 still produces a proportional plan (though 100 is the goal). Trade-only mode applies that formula directly: the dollars sold in overweighted assets equal the dollars bought in underweighted ones, so the plan costs nothing but turnover. New-money-first mode is smarter when you are actively contributing: instead of selling, the calculator pours new dollars into the underweighted assets until either the new money runs out or every asset hits target — an iterative water-fill that only generates sells if contributions cannot close the gap. Finally, the drift check flags every position whose current weight differs from target by more than your rebalancing band (say ±5%), so you can distinguish urgent rebalancing from routine drift not worth the trading costs or taxable events.
Expert Insights
Rebalancing Controls Risk, Not Returns
The point of rebalancing is to keep your portfolio's volatility and drawdown profile at the level you planned — not to maximize growth. A never-rebalanced equity-heavy portfolio can beat a rebalanced one in bull markets, but it will also crash harder than you can stomach. The return sacrifice is usually small; the risk control is the entire value.
New Money Beats Selling in Taxable Accounts
Selling an appreciated asset in a taxable account creates capital gains. Directing new contributions to underweighted positions restores the allocation with zero taxes and often zero trading costs. Many advisors rebalance taxable accounts only on a wide band and do the fine-tuning with contributions inside tax-sheltered IRAs and 401(k)s, where selling is tax-neutral.
Bands Save You from Overtrading
Rebalancing at every quarterly checkpoint generates trades for 1–2% drifts that vanish by next quarter anyway. A threshold-based rule — act only when a position drifts beyond, say, 5 percentage points from target — cuts trading frequency by more than half in backtests with near-identical risk control. That threshold is exactly what this tool's band setting models.
Actionable Tips
- 1
Check Drift Quarterly, Act Only Past Your Band
Put a quarterly calendar reminder to update your values here. If no position has drifted outside your band, do nothing — drift under 5 points rarely justifies trading costs or tax bills.
- 2
Rebalance With Contributions in Taxable, Trades in Tax-Sheltered
Use the New Money First mode for your taxable brokerage: steer each deposit to the laggards. Do the precise trade-based rebalance inside your IRA or 401(k), where sells are tax-free, and let the two together hit the same targets.
- 3
Write the Target Mix Down Before You Trade
Decide the allocation while the market is calm, enter it here, and save the URL. When equities have rallied 30%, the only thing standing between you and panic-chasing is that written target — the calculator just executes it.
Real-World Examples
Elena's Drift Surprise
Elena set a 70/30 stock/bond mix at 45 and forgot it. Three years of strong stocks later, this tool showed she was running 81% equity — a risk level she would never have chosen consciously. She sold about $6,200 of stock funds and moved it into bonds, restoring 70/30 and shaving her projected worst-case drawdown by several points before the next downturn tested her.
Marcus Avoids the Tax Bill
Marcus held a taxable account and an IRA with a combined 60/40 target, and his taxable side had drifted overweight stocks. Selling would have triggered a $2,400 capital gains bill. Instead, he toggled New Money First, steered that quarter's $8,000 contribution entirely into bonds in the IRA, and closed most of the drift without a single taxable sale.
The Family That Rebalanced Through a Bear Market
During a 20% equity drawdown, the Nguyen family's 75/25 portfolio slid to 68/32 — exactly the moment their plan said to buy stocks, not sell. The calculator quantified it: $18,000 from bonds into equities. It was terrifying to execute, but that rebalance added a full two percentage points to their next recovery, and the habit has repeated every cycle since.
Glossary of Terms
- Target Allocation
- The long-run mix of asset classes you choose to hold — e.g. 60% stocks, 30% bonds, 10% cash — reflecting your risk tolerance and time horizon.
- Drift
- The gap between an asset's current portfolio weight and its target weight, caused by different asset classes growing at different rates.
- Rebalancing Band
- A tolerance threshold (such as ±5 percentage points) — rebalancing is triggered only when drift exceeds the band, keeping trading costs and taxes down.
Frequently Asked Questions
Everything you need to know about this topic.
Ivy Sinclair-Wren
Financial Chaos Analyst
Ivy Sinclair-Wren is a Financial Chaos Analyst covering investing, AI, wealth psychology, and the emotional consequences of opening finance apps during market crashes. Based in Melbourne, she specializes in demystifying the US tax code and helping users navigate the intersection of spreadsheet logic and human irrationality.