One nibble is equal to

A nibble has 16 potential values thanks to its four bits, which is the same as one hexadecimal digit. As a result, a nibble is also known as a hex digit. Because of the four bits that make up each nibble, nibbles are also referred to as “quad bits” in data transfers.
One nibble is half byte.
1 byte = 8 bits.
Hence, $$\frac{1}{2}$$ byte (one nibble) = 4 bits.