There are exactly 16 ounces in a pound in the avoirdupois system used for everyday weight in the United States, so 1 pound = 16 ounces and 1 ounce = 1/16 pound (about 28.35 grams).
The pound (lb) and ounce (oz) are the two units most people in the US use to weigh food, packages, and their own body weight. The relationship is fixed and simple — but there is a catch worth knowing, because “ounce” can mean more than one thing.
The basic conversion
In the avoirdupois system — the standard for weighing groceries, produce, mail, and people — one pound is divided into 16 equal ounces. That makes the math straightforward:
- 1 pound = 16 ounces
- 1 ounce = 1/16 pound = 0.0625 pound
- To go from pounds to ounces, multiply by 16.
- To go from ounces to pounds, divide by 16.
Quick reference table
| Pounds | Ounces | Grams (approx.) |
|---|---|---|
| 1/4 lb | 4 oz | 113 g |
| 1/2 lb | 8 oz | 227 g |
| 3/4 lb | 12 oz | 340 g |
| 1 lb | 16 oz | 454 g |
| 2 lb | 32 oz | 907 g |
| 5 lb | 80 oz | 2,268 g |
| 10 lb | 160 oz | 4,536 g |
One avoirdupois ounce is defined as exactly 28.349523125 grams, and one pound is exactly 453.59237 grams. Those precise figures come from the international agreement that fixed the pound relative to the metric kilogram.
The important catch: weight ounces versus fluid ounces
The single most common mistake is confusing the ounce of weight with the fluid ounce of volume. They share a name but measure completely different things.
| Unit | Measures | Relationship |
|---|---|---|
| Ounce (oz), avoirdupois | Weight/mass | 16 oz = 1 pound |
| Fluid ounce (fl oz) | Volume | 8 fl oz = 1 US cup |
A pint of water happens to weigh close to a pound, which is where the old saying “a pint’s a pound the world around” comes from — but that is a rough coincidence for water only, not a rule. For other liquids and for solids, weight and volume are not interchangeable. If you are working with volume, see our guides on how many ounces are in a cup and how many cups are in a quart.
Troy ounces are different again
Precious metals such as gold and silver are weighed in troy ounces, and the troy system does not use 16 to a pound. A troy pound contains only 12 troy ounces, and a troy ounce (about 31.10 grams) is heavier than an avoirdupois ounce (about 28.35 grams). So a troy pound is actually lighter than a standard pound overall. Unless you are dealing with bullion, the everyday 16-ounce avoirdupois pound is the one you want.
Converting to and from grams
Because most of the world weighs food in grams and kilograms, it helps to be able to cross over. One pound is about 454 grams, and one kilogram is about 2.205 pounds. To convert ounces to grams, multiply by 28.35; to go the other way, divide by 28.35. Our guide on how many grams are in an ounce covers that step in more detail, and for recipe work you may also want how many grams are in a cup, which explains why volume and weight do not line up.
Converting fractions of a pound
Because 16 divides cleanly into common fractions, part-pound weights are easy to picture. A quarter pound is 4 ounces, a half pound is 8 ounces, and three-quarters of a pound is 12 ounces. A tenth of a pound is 1.6 ounces, which is why decimal-pound readouts on some scales (for example, 1.5 lb) do not always match the ounce markings you might expect — 1.5 lb is 24 ounces, or 1 pound 8 ounces, not 1 pound 5 ounces. When a recipe or label mixes decimal pounds and ounces, convert everything to one unit first to avoid slip-ups.
Everyday examples
- A standard box of butter in the US is 1 pound, or 16 ounces, split into four 4-ounce sticks.
- Deli meat ordered as “half a pound” is 8 ounces.
- A newborn’s weight given as “7 pounds 8 ounces” means 7.5 pounds, because 8 ounces is half a pound.
- A 16-ounce can or package is exactly 1 pound by weight.
Why the pound has 16 ounces
The avoirdupois system, whose name comes from Old French for “goods of weight,” became the English standard for general trade and settled on 16 ounces to the pound. The United States kept it after independence, and in 1959 an international agreement precisely defined the pound as 0.45359237 kilogram so that measurements would match across countries. That definition is what makes today’s conversions exact rather than approximate.
Reading scales and shipping weights
Most US kitchen and postal scales let you switch between pounds-and-ounces and decimal pounds or grams. For shipping, carriers often round up to the next whole pound or next ounce, so a package weighing 16.2 ounces may be billed as more than one pound — worth knowing when a rate jumps at a round number. When precision matters, weigh in grams and convert once at the end rather than rounding at each step, since repeated rounding between ounces and pounds can quietly add up. A single reliable scale removes almost all of these headaches.
The bottom line
For any everyday weight — food, shipping, or body weight — remember 16 ounces to the pound and you can convert instantly by multiplying or dividing by 16. Just keep the two special cases in mind: fluid ounces measure volume, not weight, and troy ounces (used only for precious metals) run 12 to the troy pound.
