Do percentages need to sum to 100%?

Yes for this two-asset view. Adjust inputs accordingly.

Can I include other assets?

Not here. Use a weighted approach or expand inputs for more asset classes.

Are taxes/fees included?

No. Consider tax impact and fees before trading.

Is this investment advice?

No. It’s a planning tool; consult a financial professional for advice.

Can I set tolerance bands?

Not in this simple calculator; adjust manually.

How often should I rebalance my portfolio?

There is no single right answer. Many investors rebalance on a schedule (for example, annually or semiannually) or when allocations drift beyond set thresholds (for example, 5 percentage points away from target). This calculator can support either approach by helping you quantify the trades needed whenever you decide it’s time to rebalance.

Can I rebalance using contributions only?

Often, yes—especially if the drift is small. Direct new contributions toward the underweight asset and see if that closes the gap without selling anything. This can reduce taxes in taxable accounts.

What if my current allocations don’t sum to 100%?

The calculator will still compute values based on the inputs, but the results may not reflect a realistic portfolio. If you have cash or other assets, either include them in a broader tool or adjust the percentages so stocks and bonds represent the full 100% of what you’re modeling.

Is rebalancing the same as market timing?

No. Rebalancing is a rules‑based way to maintain your target risk level. It does not attempt to predict market direction; it simply restores your planned mix after it drifts.

finance calculator

Portfolio Rebalancing Calculator

Calculate trades needed to move from current weights to target weights given total portfolio value.

Results

Current stocks: $60,000
Current bonds: $40,000
Target stocks: $60,000
Target bonds: $40,000
Buy/(sell) stocks: $0
Buy/(sell) bonds: $0

Overview

Over time, market moves push your portfolio away from its target allocation—stocks might rally and become a larger slice of the pie, or bonds might hold steady while equities fall. Rebalancing is the process of bringing your holdings back in line with your target mix.

This portfolio rebalancing calculator focuses on a simple two‑asset case (stocks and bonds). Given your total portfolio value, current percentage allocation, and target allocation, it tells you how much to buy or sell in each asset to get back to your desired weights.

Rebalancing is less about maximizing returns and more about maintaining a risk profile that matches your plan. When stocks run up, your portfolio can become riskier than intended. When stocks fall, it can become too conservative. Rebalancing helps keep your risk level steady and prevents the portfolio from drifting far from your intended strategy.

This tool is intentionally straightforward: it ignores tax and trading friction so you can see the “pure” allocation math first. Use it to estimate the direction and scale of trades, then adapt the results to your real‑world constraints such as tax lots, transaction costs, minimum fund amounts, or employer plan options.

Rebalancing can also support discipline. By selling a portion of what has outperformed and buying what has lagged, you avoid chasing recent winners or letting losses dictate your long‑term risk exposure. The math is simple, but the behavioral benefit can be meaningful over long horizons.

How to use this calculator

Enter your total portfolio value (combined value of stocks and bonds you are modeling).
Enter your current stock and bond percentages based on recent statements or your own calculations.
Enter your desired target percentages for stocks and bonds; together they should add up to 100% in this simple model.
Review the current and target dollar allocations the calculator shows for each asset class.
Check the suggested buy/(sell) amounts for stocks and bonds to see how much you would need to trade to reach your target allocation.
Use these trade amounts as a starting point, then refine based on tax considerations, transaction costs, and any additional asset classes you hold.

Inputs explained

Portfolio value: The total dollar value of the portion of your portfolio you are rebalancing between stocks and bonds. This might be a single account or the combined value of multiple accounts.
Current stocks (%): The percentage of your portfolio currently invested in stocks (or stock funds). You can compute this from your latest statement by dividing stock value by total portfolio value.
Current bonds (%): The percentage of your portfolio currently invested in bonds (or bond funds). In this two‑asset model, stocks% + bonds% should equal 100%.
Target stocks (%): Your desired stock allocation, such as 60% in a classic 60/40 portfolio. This reflects your risk tolerance and long‑term plan.
Target bonds (%): Your desired bond allocation. In this model, target stocks% + target bonds% should equal 100%.

Outputs explained

Current stocks: The current dollar amount in stocks based on your portfolio value and current stock percentage.
Current bonds: The current dollar amount in bonds based on your portfolio value and current bond percentage.
Target stocks: The target dollar amount that should be invested in stocks to match your target stock percentage.
Target bonds: The target dollar amount that should be invested in bonds to match your target bond percentage.
Buy/(sell) stocks: The amount of stocks to buy (if positive) or sell (if negative) to move from the current stock allocation to the target stock allocation.
Buy/(sell) bonds: The amount of bonds to buy or sell to reach your target bond allocation. In a simple two‑asset model, this should be the opposite of the stock trade.

How it works

You enter your total portfolio value and your current stock and bond percentages. The calculator multiplies the total value by these percentages to compute current dollar amounts in each asset.

You then enter your desired target percentages for stocks and bonds. The calculator multiplies the total portfolio value by the target percentages to determine target dollar amounts.

For each asset, the required trade is Trade amount = Target value − Current value. A positive number indicates a buy; a negative number indicates a sale.

Because this is a two‑asset model, stock and bond trades should offset (ignoring cash), illustrating how you would shift dollars between them to rebalance.

Formula

Let V = total portfolio value
Let c_s = current stock %, c_b = current bond %
Let t_s = target stock %, t_b = target bond %

Current stock value = V × (c_s ÷ 100)
Current bond value  = V × (c_b ÷ 100)
Target stock value  = V × (t_s ÷ 100)
Target bond value   = V × (t_b ÷ 100)

Stock trade = Target stock value − Current stock value
Bond trade  = Target bond value − Current bond value

When to use it

Planning trades in a brokerage or retirement account to rebalance back to a long‑term 60/40, 70/30, or other stock/bond allocation.
Checking how far your portfolio has drifted from target after market moves and how much capital needs to shift to get back on track.
Evaluating different target allocations by plugging in alternative stock/bond mixes and seeing the dollar impact on required trades.
Using as a teaching tool when explaining asset allocation and rebalancing to clients or family members.
Coordinating rebalancing across multiple accounts by modeling the combined stock/bond weights, then deciding where to place trades tax-efficiently.
Estimating how much new cash to direct into stocks or bonds instead of selling when you want to rebalance with contributions.
Determining whether a small drift is large enough to justify trades or whether you can wait until the next scheduled rebalance.
Comparing the impact of different glide‑paths (for example, 80/20 today, 70/30 in five years) on immediate trade needs.
Stress‑testing how a change in risk tolerance (e.g., moving to a more conservative allocation) affects required trades.

Tips & cautions

Set percentages that sum to 100%. Adjust for additional asset classes separately if needed.
Consider tax location and transaction costs before trading; rebalancing in tax‑advantaged accounts is often more efficient.
Small drifts may not need trades; many investors use tolerance bands (e.g., ±5%) or calendar schedules.
If you add contributions regularly, you can often rebalance by directing new money to the underweight asset instead of selling.
Use your total portfolio value across accounts when possible; it gives a clearer picture of overall allocation.
Revisit your target allocation when your goals, time horizon, or risk tolerance change—not just when markets move.
If you keep a cash buffer, account for it separately so stock/bond targets still reflect investable assets.
Simplified two-asset view; does not handle multiple asset classes or tax implications.
Assumes immediate trades at current values; ignores transaction costs.
Does not account for cash holdings, alternative assets, or the need to maintain minimum dollar thresholds in certain funds or accounts.
Does not model wash-sale rules, capital gains tax lots, or account-specific rebalancing strategies (such as rebalancing within tax-advantaged accounts only).
Does not enforce that current and target percentages sum to 100%; if they don’t, the trade amounts may not reflect a realistic portfolio.
Does not include constraints like trading windows, contribution limits, or employer plan restrictions.

Worked examples

$100k, current 70/30, target 60/40

Total portfolio = $100,000.
Current stocks = 70% × $100,000 = $70,000; current bonds = 30% × $100,000 = $30,000.
Target stocks = 60% × $100,000 = $60,000; target bonds = 40% × $100,000 = $40,000.
Stock trade = $60,000 − $70,000 = −$10,000 → Sell $10,000 of stocks.
Bond trade = $40,000 − $30,000 = +$10,000 → Buy $10,000 of bonds.

$250k, current 55/45, target 60/40

Total portfolio = $250,000.
Current stocks = 55% × $250,000 = $137,500; current bonds = 45% × $250,000 = $112,500.
Target stocks = 60% × $250,000 = $150,000; target bonds = 40% × $250,000 = $100,000.
Stock trade = $150,000 − $137,500 = +$12,500 → Buy $12,500 of stocks.
Bond trade = $100,000 − $112,500 = −$12,500 → Sell $12,500 of bonds.

Rebalance using new cash

Portfolio value = $80,000, current 65/35, target 60/40.
Current stocks = $52,000; target stocks = $48,000 (stocks are $4,000 overweight).
If you plan to add $4,000 of new money, you could direct it to bonds instead of selling stocks.
Result: stocks stay at $52,000, bonds increase to $32,000, and the allocation moves closer to 60/40 without a taxable sale.

Deep dive

Calculate portfolio rebalancing trades by entering total portfolio value, your current stock/bond weights, and your target weights to see buy/sell amounts.

Use this two-asset rebalancing calculator to plan allocation adjustments after market moves while keeping your stock/bond mix aligned with your risk profile.

Methodology & assumptions

Inputs are converted to percentages between 0 and 100, then divided by 100 to create decimal weights.
Current values are calculated as Portfolio value × Current percentage.
Target values are calculated as Portfolio value × Target percentage.
Trade amounts are calculated as Target value − Current value for each asset.
Positive trade values indicate buys; negative values indicate sells.
The calculator does not adjust for cash or other assets beyond the two inputs.

Sources

Investor.gov — Asset AllocationExplains how asset allocation affects risk and why maintaining a target mix matters.
FINRA — Portfolio RebalancingOverview of rebalancing concepts, benefits, and common approaches.

FAQs

Do percentages need to sum to 100%?: Yes for this two-asset view. Adjust inputs accordingly.
Can I include other assets?: Not here. Use a weighted approach or expand inputs for more asset classes.
Are taxes/fees included?: No. Consider tax impact and fees before trading.
Is this investment advice?: No. It’s a planning tool; consult a financial professional for advice.
Can I set tolerance bands?: Not in this simple calculator; adjust manually.
How often should I rebalance my portfolio?: There is no single right answer. Many investors rebalance on a schedule (for example, annually or semiannually) or when allocations drift beyond set thresholds (for example, 5 percentage points away from target). This calculator can support either approach by helping you quantify the trades needed whenever you decide it’s time to rebalance.
Can I rebalance using contributions only?: Often, yes—especially if the drift is small. Direct new contributions toward the underweight asset and see if that closes the gap without selling anything. This can reduce taxes in taxable accounts.
What if my current allocations don’t sum to 100%?: The calculator will still compute values based on the inputs, but the results may not reflect a realistic portfolio. If you have cash or other assets, either include them in a broader tool or adjust the percentages so stocks and bonds represent the full 100% of what you’re modeling.
Is rebalancing the same as market timing?: No. Rebalancing is a rules‑based way to maintain your target risk level. It does not attempt to predict market direction; it simply restores your planned mix after it drifts.

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This portfolio rebalancing calculator is a simplified planning aid and does not account for all aspects of portfolio management, including taxes, transaction costs, account type differences, or multiple asset classes. It is not investment, tax, or financial advice. Before implementing any rebalancing strategy or executing trades, review your full financial situation, consider tax implications and fees, and consult a qualified financial professional if needed.