The cash ratio is the most conservative liquidity ratio. It measures a company's ability to pay off its current liabilities using only its cash and cash equivalents — no receivables, no inventory, no other current assets. It answers the strictest possible version of the liquidity question: if the company had to pay every short-term obligation right now using only the cash it has on hand, could it?
In practice, a cash ratio of 1.0 or higher is uncommon outside of technology companies and financial institutions. Most businesses do not keep enough idle cash to cover all current liabilities because doing so would be capital-inefficient — that cash could be invested in the business, used to pay down debt, or returned to shareholders. A low cash ratio is not inherently concerning as long as the company has adequate receivables turnover and inventory liquidity to bridge the gap.
The cash ratio is most useful as a stress test metric and in comparing companies within capital-intensive industries where receivables quality may be uncertain. It is also useful for evaluating companies going through financial distress, where the ability to meet obligations from cash on hand is the most relevant measure.