Portfolio rebalancing calculator

Enter your holdings, what each one is worth, the price of one share and the weight you want. Then choose how much you're adding: the calculator tells you how many shares to buy to get closer to your target.

Nothing is sent anywhere: the maths runs on your device.

How to rebalance an ETF portfolio

A portfolio drifts on its own: the holding that rises weighs more and more, the one that falls less and less. Rebalancing brings each holding back to the weight you chose. There are two ways to do it, and the calculator does both.

Buy only: rebalancing with your deposits

If you add money every month, you can correct the portfolio without selling anything: put the new money mostly into whatever is below target. You pay no selling fees and realise no gains. The calculator starts from what is furthest from target, buys whole shares and, if what's left still pays for a share, adds one where it's needed most. If the deposit is small next to the portfolio, the target takes a few months to reach.

A full rebalance, with a threshold

When a holding has drifted a long way, a deposit isn't enough: you sell part of what is above target and buy what is below. The threshold stops you from moving everything for a few decimals. With a 5-point threshold, a holding meant to weigh 60% stays as it is while it sits between 55% and 65%. The calculator sells first, in the share counts closest to the right amount, then buys the rest with what the sales raise and your deposit.

Why whole shares

At your broker you buy whole shares of an ETF: a plan that says "buy 3.7 shares" can't be placed. That's why the calculator rounds down and tells you what's left over. The rest isn't lost: it's there for your next deposit.

What it doesn't do

The calculator does the maths on the weights you choose. It doesn't tell you which ETFs to buy or which allocation to pick, and the prices you enter are indicative: when you buy, your broker's price is the one that counts. This is not financial advice.