Portfolio Rebalancing Calculator

What this calculator does

You may start with a deliberate split, say 60% stocks and 40% bonds, but when stocks rise faster than bonds, the stock share grows until the portfolio you own is riskier than the one you designed. Rebalancing trims what has grown too large and tops up what has shrunk, so the mix returns to plan. Enter what you hold in stocks and bonds today and the stock allocation you want, and the calculator returns the buy and sell amounts for each side.

A positive number means buy that amount; a negative number means sell. In a two-asset portfolio the total stays the same, so the two trades mirror each other: one side's sale funds the other side's purchase.

How the numbers are calculated

The calculator adds the current stock and bond values to get your total portfolio value. It applies your target stock percentage to that total to find the ideal stock holding; the rest is the ideal bond holding. It then compares those ideals with your actual holdings:

• Stock trade = (total × target stock %) − current stock value
• Bond trade = (total × (1 − target stock %)) − current bond value

Suppose you hold 7,000 in stocks and 3,000 in bonds, a total of 10,000, and your target is 60% stocks. The ideal stock holding is 6,000, so you are 1,000 over and the stock trade is −1,000 (sell). The ideal bond holding is 4,000, so you are 1,000 short and the bond trade is +1,000 (buy). Selling 1,000 of stock and buying 1,000 of bonds restores the 60/40 mix exactly.

Why rebalancing matters

Rebalancing keeps your risk where you decided it should be; it is not a way to chase higher returns. A portfolio left untouched through a long bull market becomes stock-heavy, so it falls harder than planned when a downturn arrives. Rebalancing makes you sell a little of what has done well and buy a little of what has lagged, the opposite of what most investors instinctively want to do, and that keeps a plan on track.

A rule, such as rebalancing once a year or whenever an asset drifts past a set band, also takes emotion out of deciding when to take profits or add to a falling asset. The calculator supplies the numbers so the routine takes a minute.

Choosing your target and when to act

Your target allocation should come from your goals, your time horizon, and how much volatility you can live with, not from recent market performance. A younger investor with decades ahead might hold 80% or 90% in stocks; someone close to needing the money might hold far less. Calendar-based rebalancing checks on a fixed schedule such as once a year; threshold-based rebalancing acts only when an asset has drifted a chosen distance, often five percentage points, from its target.

A practical compromise is to check on a schedule but trade only if the drift is meaningful, which avoids paying costs to correct a trivial imbalance. In a taxable account it is often cheapest to rebalance by steering new contributions toward the underweight asset instead of selling, which avoids capital-gains tax.

Reading the result

The stock trade usually shows the largest imbalance, but read both trades together. If both are near zero, your portfolio is already on target and there is nothing to do. When the trades are large, consider whether to rebalance in one go or spread it over a couple of contributions for cost and tax reasons. The donut chart shows the target split, a quick check that your chosen percentage is the mix you intended.

About This Portfolio Rebalancing Calculator

Use this portfolio rebalancing calculator to get an instant estimate based on the figures you enter. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.