What is portfolio rebalancing?

Portfolio rebalancing is the process of adjusting your holdings so that your asset mix (for example, stocks, bonds, and cash) returns to your target allocation. Over time, market movements cause your weights to drift away from target; rebalancing restores your intended risk and return profile.

How does this tool calculate rebalance trades?

The tool sums your current holdings, applies your target percentages to the total (plus any new contributions), and then compares target values to current values. The difference for each asset class becomes a suggested buy or sell amount to move you back to target.

Do I have to rebalance exactly to the suggested amounts?

No. The suggested trades are a mathematical reference. You can round amounts, consider transaction costs, and adjust for tax implications. Many investors rebalance within a tolerance band rather than to an exact dollar.

How often should I rebalance my portfolio?

Common approaches include calendar-based rebalancing (for example, annually or quarterly) and threshold-based rebalancing (only when an asset class drifts beyond a set percentage from target). The right cadence depends on your strategy, costs, and tax situation.

Does this tool account for taxes and transaction costs?

No. The tool focuses on allocation math and suggested trades. It does not model taxes, bid-ask spreads, or commissions. Always consider tax consequences and trading costs before rebalancing, especially in taxable accounts.

Can I export the rebalance plan?

Yes. Use the Export CSV button to download a table of asset classes, current values, target values, and suggested trades. You can import the file into a spreadsheet or share it with an advisor.

Portfolio Rebalancing Tool

Compare your current asset mix with your target allocation and see the exact buy and sell trades needed to rebalance your portfolio.

Current stocks value Current bonds value Current cash/other value

Target stocks (%) Target bonds (%) Target cash/other (%)

New contribution amount (optional) Drift threshold (%) Estimated trade cost per asset

Tip: Make sure your target percentages sum to 100%. Use the drift threshold to decide when rebalancing is worth the cost.

Important: This tool focuses on allocation math and suggested trades. It does not model taxes, bid-ask spreads, or commissions. Use this for planning and discussion, and confirm details with your broker or advisor before placing any orders.

Portfolio rebalancing formulas

Rebalancing is driven by a few simple formulas. They help you translate your current holdings and target allocation into concrete buy and sell amounts. The tool uses these formulas to calculate how far you’ve drifted and what trades would bring you back to your desired mix.

1. Total portfolio value

Total value = Current stocks + Current bonds + Current cash/other + New contribution

This gives the base amount that your target percentages will be applied to. If you don’t plan to add new money, set the contribution to zero.

2. Target value by asset class

Target value for asset i = Total value × (Target percentage for asset i ÷ 100)

Each asset class gets a target dollar value based on your chosen allocation. The sum of all target values equals the total portfolio value.

3. Drift from target

Current weight for asset i = Current value for asset i ÷ Total value

Drift for asset i = Current weight for asset i − (Target percentage for asset i ÷ 100)

Drift measures how far each asset class has moved away from its target weight. Large positive drift means the asset is overweight; large negative drift means it is underweight.

4. Suggested trade amount

Trade amount for asset i = Target value for asset i − Current value for asset i

If Trade amount > 0 → Buy that amount
If Trade amount < 0 → Sell |Trade amount|

These trade amounts show how much you would buy or sell to rebalance exactly to target. In practice, you may round amounts or adjust for transaction costs and taxes.

The tool applies these formulas to your inputs and then summarizes total amount traded, maximum drift, and a table of suggested trades. You can use this as a starting point for your own rebalancing decisions.

How portfolio rebalancing fits into long-term investing

When you design an investment plan, you usually start with an asset allocation: a mix of stocks, bonds, cash, and sometimes alternatives that matches your risk tolerance and goals. Over time, markets move. Stocks may rally while bonds lag, or vice versa. As this happens, your portfolio drifts away from the allocation you originally chose. Rebalancing is the process of nudging it back.

Rebalancing matters because your asset mix is one of the biggest drivers of risk and return. If stocks grow to dominate your portfolio, you may be taking more risk than you intended. If bonds or cash swell, you might be too conservative. By periodically checking your allocation and making small adjustments, you keep your portfolio aligned with your plan instead of with whatever the market happened to do.

Understanding drift and thresholds

Drift is simply the difference between your current weight and your target weight for each asset class. For example, suppose your target is 60% stocks, 30% bonds, and 10% cash. After a strong stock market, you might find that you’re at 70% stocks, 23% bonds, and 7% cash. Stocks are now 10 percentage points overweight, while bonds and cash are underweight.

Many investors use thresholds to decide when to rebalance. A common rule is to rebalance when an asset class drifts more than 5 percentage points from target. In the example above, stocks have crossed that threshold, so the tool would suggest selling some stocks and buying bonds or cash to restore balance. Thresholds help you avoid over-trading while still keeping risk in check.

How the tool models your rebalance

The portfolio rebalancing tool starts by summing your current holdings and any new contributions. It then applies your target percentages to that total to compute target dollar values for each asset class. Next, it compares those target values to your current values. The difference becomes a suggested trade: positive values indicate buys, negative values indicate sells.

For each asset class, the tool also calculates current weights and drift from target. This gives you a clear picture of which parts of your portfolio are driving risk. The summary shows total amount traded and maximum drift, so you can quickly judge whether rebalancing is worth the effort and cost.

Worked example

Example: Imagine you have $45,000 in stocks, $25,000 in bonds, and $5,000 in cash. Your target allocation is 60% stocks, 30% bonds, and 10% cash, and you plan to add $1,000 in new contributions.

Total value = 45,000 + 25,000 + 5,000 + 1,000 = $76,000.
Target stocks = 76,000 × 0.60 = $45,600.
Target bonds = 76,000 × 0.30 = $22,800.
Target cash = 76,000 × 0.10 = $7,600.

Compared to your current values, the tool might suggest buying a small amount of stocks with part of your contribution, selling some bonds, and increasing cash. The exact trades depend on how you choose to deploy the new contribution, but the math gives you a clear starting point.

Practical tips for using the tool

Use the drift threshold input to decide when rebalancing is necessary. If drift is below your threshold, you may choose to wait.
Consider rebalancing inside tax-advantaged accounts first, where trades may not trigger immediate tax consequences.
Combine rebalancing with new contributions by directing new money to underweight asset classes instead of selling existing holdings.
Export the CSV and keep a record of your rebalance decisions. This can help you stay consistent over time.

Rebalancing doesn’t have to be complicated or frequent. A simple, rules-based approach supported by a clear calculator can keep your portfolio aligned with your long-term plan without turning investing into a full-time job.

Frequently Asked Questions

Do my target percentages have to sum to 100%?

Yes. The tool assumes your target allocation covers the entire portfolio. If your targets don’t sum to 100%, the suggested trades will not reflect a coherent plan. Adjust your targets until they add up to 100% before running the calculation.

What if I have more than three asset classes?

This version focuses on three broad buckets: stocks, bonds, and cash or other. If you have more asset classes, you can group similar holdings together (for example, all equities as “stocks”) or build a more detailed spreadsheet using the exported CSV as a starting point.

How does the drift threshold affect the results?

The drift threshold doesn’t change the math; it helps you interpret it. The tool calculates drift for each asset class and highlights the maximum drift. You can compare that value to your threshold to decide whether rebalancing is warranted right now.

Can I rebalance using only new contributions?

Yes. If you prefer not to sell existing holdings, you can direct new contributions to underweight asset classes. Enter your planned contribution and review the suggested trades. In practice, you may choose to buy only the underweight assets and skip sells.

Does this tool tell me which specific funds or securities to trade?

No. The tool works at the asset-class level. It shows how much to move between broad categories like stocks, bonds, and cash. You decide which specific funds or securities to buy or sell within each category based on your investment lineup.

Is this personalized investment advice?

No. The tool is for education and planning. It illustrates how rebalancing works and provides a numerical reference, but it does not account for your full financial situation. Consider consulting a qualified advisor before making significant changes to your portfolio.