As a Singaporean, do we pay withholding tax on capital gains when we sell a US stock? Or is it only a 30% tax on dividends?

30% wht tax on US-domiciled stock, not US-listed. best in mind

Not subjected to capital gains tax but we are liable for the 30% dividend withholding tax when holding an US stock/equities (listed in the US exchange - NASDAQ/NYSE etc.). When you sell the stock, you will pay the sell commision brokerage fees which is dependent on the brokerage you are using.