The only rule you need
A pound is exactly 16 ounces, so multiply by 16 to go to ounces and divide by 16 to come back. For fractional pounds the whole number stays as pounds and the decimal becomes ounces: 2.3 lb is 2 lb plus 0.3 × 16 = 4.8 oz.
Pounds to ounces reference
| Pounds | Ounces | Context |
|---|---|---|
| 0.25 lb | 4 oz | quarter pound |
| 0.5 lb | 8 oz | half pound, a stick of butter |
| 0.75 lb | 12 oz | three-quarter pound |
| 1 lb | 16 oz | one pound |
| 1.5 lb | 24 oz | — |
| 2 lb | 32 oz | — |
| 2.5 lb | 40 oz | a bag of coffee |
| 5 lb | 80 oz | a bag of flour |
| 10 lb | 160 oz | — |
For postage, round the final ounces up: 13.1 oz is billed as 14 oz.
Weight ounces are not fluid ounces
This is the trap the word “ounce” sets. An ounce of weight (oz) and a fluid ounce of volume (fl oz) are different measurements that happen to share a name, and for most substances they give different numbers for the same amount.
Same word, two scales: this converter uses the weight ounce, so 16 oz make a pound, while 16 fl oz make a pint.
- Troy is a different pound. Gold and silver use troy ounces, and a troy pound is only 12 oz. A regular avoirdupois pound is 16 oz.
- Mixed weights aren’t decimals. 7 lb 11 oz is 7 + 11⁄16 = 7.6875 lb, not 7.11 lb.
Common questions
How many ounces are in a pound?
Exactly 16 ounces, in the avoirdupois system used for everyday weight in the US and UK. So 1 lb is 16 oz and half a pound is 8 oz.
How do I convert 3 lb 5 oz to ounces?
Multiply the pounds by 16 and add the extra ounces: 3 times 16 is 48, plus 5 is 53 oz. Note that 3 lb 5 oz is not 3.5 lb.
Is an ounce the same as a fluid ounce?
No. An ounce measures weight (about 28.35 g), while a fluid ounce measures volume (about 29.57 mL). They only line up for water, and even then only roughly.
