half as big/much/good as

idiom

—used to say that the size, amount, or quality of one thing is half or nearly half that of another

The bush is half as tall as the tree.

This dress costs half as much as that one.

If 100 people were expected and 50 came, only half as many people came as were expected.

If he can play the guitar half as well as he can sing, he should have quite a career.