Free · Weight and mass converters

Pounds, Ounces & Mixed Mass Entries

Convert avoirdupois pounds and ounces to metric mass, or add separate pound and ounce amounts into a combined entry.

Formula & worked example
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Calculator inputs

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How to use this calculator

Enter the known values in the units shown. Results update as you type.
Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

2.5 lb equals 40 oz, or 2 lb 8 oz, and exactly 1,133.980925 g. The separate addition section combines 2 lb and 8 oz into the same total.

1 lb = 16 oz = 453.59237 g; total ounces = 16 × pound portion + ounce portion

Worked example

Enter these known values and leave the other values blank.

Total avoirdupois pounds: 2.5 lb
Pound portion to add: 2 lb
Ounce portion to add: 8 oz

Equivalent avoirdupois ounces: 40 oz
Equivalent mixed pounds and ounces: 2:8 lb / oz
Equivalent metric mass: 1133.981 g
Equivalent customary mass: 0.17857143 st
Combined pound and ounce total: 2:8 lb / oz

Assumptions and limitations

Ordinary pounds and ounces mean avoirdupois mass. One pound is exactly 16 avoirdupois ounces; a troy ounce is a different optional unit.
The equivalence section and the addition section are independent. Values in one section do not automatically populate the other.
Mixed fields show pounds and remaining ounces. The addition section accepts separate quantities, including an ounce portion greater than 16, and normalizes the total.
Signed mass differences are supported for arithmetic. In a mixed signed entry, the leading sign applies to the whole mixed quantity.

Common questions

Is 2.5 lb the same as 2 lb 5 oz?

No. Half a pound is eight ounces, so 2.5 lb is 2 lb 8 oz.

What if the ounce portion exceeds 16?

The combined result carries each group of sixteen ounces into an additional pound.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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