You just added to a position and noticed the cost price changed — this is not a system error. It is the cost price calculation mechanism at work. OKX spot cost price has two calculation methods. The change you see depends on which method you selected and whether you just bought or sold.
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Difference Between the Two Calculation Methods
Average cost price: Only buy orders are included. Each new buy recalculates the weighted average. Selling does not change the cost price. This method is good for judging the overall buy cost of your current position.
Cumulative cost price: Both buys and sells are included in the calculation. Selling at a profit lowers the cost price, while selling at a loss raises it. This method is good for evaluating overall trading performance, such as when you want to know "at what price will I break even overall."
If the cost price goes up after selling part of your position, that is because of the cumulative cost price feature: when the sell price is below the average cost, the loss from the sale is included in the cost, which pushes up the cost of the remaining position.
If You See the Cost Price Jump to a New Fixed Value
You may have triggered the manual edit feature. Since October 2024, OKX has supported manual editing of spot cost price. The entry is in "Trade Page > Positions and Assets > Cost Price". After editing, profit and profit rate will update accordingly, and future cost price changes from trading will continue to be calculated based on this edited value.
Easy to Confuse: Assets Overview vs Trading Account
The cost price you see may come from two different pages:
Assets Overview cost price: Covers trading account, funding account, and earn account. Transfers between accounts do not affect this number.
Trading Account cost price: Only includes assets in the trading account. Transferring funds in will affect it because the trading account now has more coins.
So if you transfer coins from your funding account to your trading account, the Assets Overview cost price stays the same, but the Trading Account cost price will be recalculated using the new buy price.
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How to Confirm
To confirm the cost price calculation method: Go to the spot trading page → tap "Settings" in the top menu → find "Spot cost price type" → check whether "Average cost price" or "Cumulative cost price" is currently selected. Once confirmed, you will understand which mechanism is causing the change you see.
To check why the cost price changed: Open "Spot Trading Positions and Assets" and look at the data source note next to the cost price. This helps you tell whether the change came from a new buy, a partial sell, or a manual edit.
Risk reminder: Cost price is only a display parameter within the OKX system. It is not the basis for your actual tax filing. Tax authorities in different countries may require you to calculate cost based on actual transaction records for tax reporting purposes.
How to verify after completing the operation: After confirming the cost price calculation method, open a small test order (for example, buy a little using a stablecoin pair) and observe how the cost price changes after buying. Compare the difference between average cost price and cumulative cost price modes. This will help you clearly understand how these two calculation methods work.
