First of all, ounces measure weight and pints measure capacity or liquid volume. Next, what is the liquid? Water? Milk? Liquid nitrogen? Molten lead? For example, a gallon (8 pints) of water weighs about 10lb (160 oz). A gallon of molten lead weighs a lot more! So we need to know the density of the liquid, that is, grams per litre, ounces per pint, pounds per gallon. So the density of water is 10 pounds per gallon approximately.
Other factors about density are temperature and quality or type. Density changes according to temperature, for example, ice is less dense than water, and that's why it floats. Composition also affects density, for example, full fat milk has a different density to skimmed milk. Quality also affects density: distilled water and seawater have different densities.
Finally, the units of measurement differ: weight can be ounces, pounds, grams, kilograms, tons, tonnes, etc.; volume can be cubic centimetres (cc), litres, gallons, pints, quarts, etc. If density is measured in metric units such as grams per millilitre, and you need ounces per pint, you need to know the conversion rates. The density of water in metric measurements is about 1 gram per cc. There are about 454 grams in a pound (1lb=16 oz), 454/16=28.4g=1oz, and 1cc=1mL, 1000cc=1L=1.76 pints. So you convert to and from imperial and metric measurements. A fluid ounce is simply an ounce of fluid so it's still 28.4g. Example: a pint of water with a density of 1g/cc is how many ounces? 1000cc=1L=1.76pints, so 1cc=1.76/1000=0.00176pints. 1g=1/28.4=0.035oz. So the density of water is 0.035/0.00176=19.9oz/pint (roughly 20oz/pint). There are 8 pints in a gallon so a gallon of water weighs = volume * density = 8*20=160oz or about 10lbs. So to convert pints of water to ounces you multiply by about 20, and to convert ounces to pints you divide by 20. That's the bottom line.
