Australian consumer confidence has plunged after the Reserve Bank lifted the cash rate to 4.6 percent, with two separate surveys showing sharp falls.

The ANZ-Roy Morgan consumer confidence index dropped 3.4 points to 67.1. The Westpac-Melbourne Institute sentiment measure fell 4.7 percent to 80.4.

Most striking was the split within the Westpac survey. Respondents interviewed after the rate hike scored just 67.2, the weakest reading since the late 1990s.

The falls show how quickly rate rises feed through to household sentiment. Higher mortgage repayments leave less for everything else, and consumers are responding by pulling back.

Retailers will be watching nervously. Confidence is a leading indicator of spending, and a sustained slump would hit an already fragile consumer economy. Economists say sentiment can turn quickly if the Bank signals a pause, but few expect relief before next year.

The Reserve Bank faces a difficult trade-off. Inflation is still too high, but each hike risks crushing the household sector it is trying to protect.