银行存款准备金比率（Required Reserve Ratio，也译作存款准备金比率、现金准备比例、准备金比例、准备金要求、存款准备率），指商业银行的初级存款中不能用于放贷的部分的比例。

为保障存款人的利益，银行机构不能将吸纳的存款全部用于发放贷款或者是进行炒股票等金融投资，必须保留一定的资金，存放在银行内（如美国）或缴存在中央银行（如中国大陆），以备客户提款的需要，这部分的存款就叫做存款准备金。而存款准备金与存款总额的比例，就是银行存款准备金比率。

The reserve requirement (or cash reserve ratio) is a central bank regulation employed by most, but not all, of the world's central banks, that sets the minimum fraction of customer deposits and notes that each commercial bank must hold as reserves (rather than lend out). These required reserves are normally in the form of deposits made with a central bank, or cash stored physically in the bank vault (vault cash).