Ounces to pounds (oz to lb)

One ounce is exactly 0.0625 pounds. 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: 16 oz x 0.0625 = 1 lb.

Going the other way, one pound is 16 ounces.

To convert without a calculator, multiply by 0.0625. Rounding that to 0.063 is within 0.8% for most purposes.

Sixteen ounces to the pound. Not twelve, which is the troy system, and not ten. The 16 is a legacy of repeated halving, which is how pre-decimal trade weights worked.

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