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Pounds and Ounces Calculator

Convert weights from pounds and ounces to kilograms, grams, and stones.

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Quick Summary

Use this when you need:

Convert baby weights between lb+oz and kilograms
Document shipping weights in both stones and kilograms
Explain to customers how package weights map to metric labels

You’ll get:Weight

How this is calculated

Formula:

mass_target = mass_source * (source_to_kilograms / target_to_kilograms)

In plain language:

Pounds plus ounces, pure pounds, stones, and metric units are all normalized into kilograms before we output the requested representation.

The formula is always visible so you can verify the math and explain your numbers to anyone who asks.

What these terms mean

Weight

Weight used in the calculation.

When to use this calculator

Convert baby weights between lb+oz and kilograms
Document shipping weights in both stones and kilograms
Explain to customers how package weights map to metric labels

Last updated: November 18, 2025

Pounds-and-ounces conversion explained

Medical charts and shipping slips in the U.S. still list weight as pounds plus ounces. The Pounds and Ounces Calculator converts that composite value into kilograms, grams, stones, or back to total pounds without forcing you to do fractional math by hand.

How the conversion works

First convert the composite measurement into total ounces ( $16\,\text{oz} = 1\,\text{lb}$ ), then multiply by the ounce factor:

M_{\text{kg}} = \frac{(\text{lb} \times 16 + \text{oz}) \times 0.028349523125}{1}

Going the other direction, convert kilograms into ounces, divide by 16 for the pound component, and keep the remainder as ounces.

Units and conversions

Unit	Relation
Pound (lb)	$1\,\text{lb} = 0.45359237\,\text{kg}$
Ounce (oz)	$1\,\text{oz} = 0.028349523125\,\text{kg}$
Stone (st)	$1\,\text{st} = 14\,\text{lb}$
Kilogram (kg)	Base SI mass
Gram (g)	$1\,\text{g} = 10^{-3}\,\text{kg}$

Worked examples

Newborn weight for an international chart
A baby weighs 8 lb 11 oz.

M_{\text{kg}} = (8 \times 16 + 11) \times 0.028349523125 = 3.94\,\text{kg}

Result: record 3.94 kg alongside the imperial value.

Metric measurement to lb+oz
A component weighs 3.2 kg. Convert to pounds and ounces for a U.S. datasheet.

\text{total oz} = \frac{3.2}{0.028349523125} = 112.88\,\text{oz}\\ \text{lb} = \lfloor 112.88 / 16 \rfloor = 7\\ \text{oz remainder} = 112.88 - 7 \times 16 = 0.88\,\text{oz}

Result: report 7 lb 0.9 oz (round to the nearest quarter ounce if needed).

Tips and pitfalls

Healthcare teams often round infant weights to the nearest ounce; keep the higher-precision kilogram value for dosing calculations.
If you’re converting to stones, divide pounds by 14; UK hospital charts usually show stones plus pounds, so keep both for clarity.
Freight carriers sometimes apply dimensional weight in pounds while customs paperwork expects kilograms—store both side by side to avoid re-weighing.
The ounce discussed here is the avoirdupois ounce; jewelers use the troy ounce (31.103 g), which changes the math.

References and further reading

Frequently Asked Questions

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Calculator info

Version:: v1.0.0
Sensitivity:: low

Last updated: November 18, 2025

Pounds-and-ounces conversion explained

How the conversion works

First convert the composite measurement into total ounces ( $16\,\text{oz} = 1\,\text{lb}$ ), then multiply by the ounce factor:

M_{\text{kg}} = \frac{(\text{lb} \times 16 + \text{oz}) \times 0.028349523125}{1}

Going the other direction, convert kilograms into ounces, divide by 16 for the pound component, and keep the remainder as ounces.

Units and conversions

Unit	Relation
Pound (lb)	$1\,\text{lb} = 0.45359237\,\text{kg}$
Ounce (oz)	$1\,\text{oz} = 0.028349523125\,\text{kg}$
Stone (st)	$1\,\text{st} = 14\,\text{lb}$
Kilogram (kg)	Base SI mass
Gram (g)	$1\,\text{g} = 10^{-3}\,\text{kg}$

Worked examples

Newborn weight for an international chart
A baby weighs 8 lb 11 oz.

M_{\text{kg}} = (8 \times 16 + 11) \times 0.028349523125 = 3.94\,\text{kg}

Result: record 3.94 kg alongside the imperial value.

Metric measurement to lb+oz
A component weighs 3.2 kg. Convert to pounds and ounces for a U.S. datasheet.

\text{total oz} = \frac{3.2}{0.028349523125} = 112.88\,\text{oz}\\ \text{lb} = \lfloor 112.88 / 16 \rfloor = 7\\ \text{oz remainder} = 112.88 - 7 \times 16 = 0.88\,\text{oz}

Result: report 7 lb 0.9 oz (round to the nearest quarter ounce if needed).

Tips and pitfalls

Healthcare teams often round infant weights to the nearest ounce; keep the higher-precision kilogram value for dosing calculations.
If you’re converting to stones, divide pounds by 14; UK hospital charts usually show stones plus pounds, so keep both for clarity.
Freight carriers sometimes apply dimensional weight in pounds while customs paperwork expects kilograms—store both side by side to avoid re-weighing.
The ounce discussed here is the avoirdupois ounce; jewelers use the troy ounce (31.103 g), which changes the math.

Quick Summary

Calculator Tool

How this is calculated

What these terms mean

Weight

When to use this calculator

Pounds-and-ounces conversion explained

How the conversion works

Units and conversions

Worked examples

Tips and pitfalls

References and further reading

Frequently Asked Questions

Related Calculators

g to lbs Converter

Grams to Ounces Calculator

Molar mass of gas

Molarity

Mole

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Was this calculator helpful?

Found an error?

Calculator info

Pounds-and-ounces conversion explained

How the conversion works

Units and conversions

Worked examples

Tips and pitfalls

References and further reading

Frequently Asked Questions

Related Calculators

g to lbs Converter

Grams to Ounces Calculator

Molar mass of gas

Molarity

Mole

Radioactive decay

Was this calculator helpful?

Found an error?

Calculator info