US cups to US pints (cup to pt)

One US cup is exactly 0.5 US pints. That ratio belongs to the customary system itself and is much older than any link to metric: the 1959 international yard and pound agreement later fixed the yard and the pound against the meter and the kilogram, but it left the ratios between customary units (feet to the yard, ounces to the pound, cups to the gallon) exactly as they were.

Worked through: 3 cup x 0.5 = 1.5 pt.

Going the other way, one US pint is 2 US cups.

To convert without a calculator, multiply by 0.5. Rounding that to 0.5 is within 0% for most purposes.

Two US cups to a US pint, which is 473 ml. A British pint is 568 ml, 20% larger, which is the same ratio as the gallon difference and for the same reason.

Precision is worth matching to the input. A measurement given as 1 cup carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.