Stones to kg Converter

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Enter decimal stones or separate stones and pounds to find the matching weight in kilograms.

Advanced options
Weight in kilograms
kg
This is the main converted weight. Display rounding does not change the stored calculation.
Equivalent decimal stones
st
The complete entered weight written as one decimal-stone value.
Equivalent total pounds
lb
This shows how the stones and optional pounds remainder were combined.
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How to use our Stones to kg Converter

  1. Choose "Decimal stones" for a value such as 12.5 st, or choose "Stones and pounds" for a reading such as 12 st 8 lb.
  2. Enter the stones value from your scale, record, or message.
  3. In "Stones and pounds," enter the pounds remainder from 0 through 13. Leave it blank if there is no remainder.
  4. Open "Advanced options" if you want to change the displayed kilogram decimal places.
  5. Select "Calculate" and check that the total pounds matches the weight format you entered.
Example inputs for Stones to kg Converter
Example inputs for Stones to kg Converter

Definitions

Stone (st): A unit of mass equal to 14 pounds.

Decimal stones: A weight written as one stones number, such as 12.5 st.

Stones and pounds: A mixed format with whole stones and a pounds remainder, such as 12 st 8 lb.

Pounds remainder: The pounds left after complete stones are counted. It can be a whole number from 0 through 13.

Kilogram (kg): A metric unit of mass. One pound equals exactly 0.45359237 kg.

Common mistakes and quick fixes

Mistake: Entering 12.8 for a reading written as 12 st 8 lb.
Fix: Choose "Stones and pounds," then enter 12 for stones and 8 for the pounds remainder.

Mistake: Treating 16.2 st as 16 st 2 lb.
Fix: Choose "Decimal stones" and enter 16.2. The decimal part of a stone is not a pounds remainder.

Mistake: Entering 14 or more as the pounds remainder.
Fix: Add one stone for each 14 lb, then enter a remainder from 0 through 13.

Mistake: Entering a decimal value for stones in "Stones and pounds."
Fix: Enter whole stones, then put the remaining whole pounds in the separate pounds field.

Mistake: Using a comma as a decimal mark, such as 12,5.
Fix: Use a decimal point for decimals, such as 12.5. Commas are only for correctly grouped thousands.

Limitations & Key Assumptions / Boundary Conditions

  • This converter changes mass units only. It does not assess healthy weight, body composition, or medical risk.
  • In "Stones and pounds," the stones value and pounds remainder must be whole numbers. Use "Decimal stones" for values such as 12.5 st.
  • A blank pounds remainder counts as 0 lb only when a valid stones value is entered.
  • The kilogram display is rounded to the selected decimal places, but the calculation uses the unrounded conversion factor.
  • A very small nonzero weight can display as 0 at low precision; use more decimal places to see it.

Methodology

Conversion method

The calculator first converts the entered weight to total pounds. It then converts pounds to kilograms using 0.45359237 kg per pound.

total pounds = decimal stones x 14

total pounds = whole stones x 14 + pounds remainder

kilograms = total pounds x 0.45359237

decimal stones = total pounds / 14

Worked example

For 12 st 8 lb, total pounds are 12 x 14 + 8 = 176 lb. Then 176 x 0.45359237 = 79.83225712 kg, which displays as 79.83 kg at two decimal places.

Rounding

The calculator keeps the full converted value for its math. "Result decimal places" changes only the displayed kilogram value.