Weight Conversion Reference
| Unit | Equivalent in kg | Clinical Use |
|---|---|---|
| 1 kg | 1.000 kg | Standard metric body weight, drug dosing |
| 1 pound (lb) | 0.4536 kg | Body weight in US, UK (alongside stone) |
| 1 stone (st) | 6.3503 kg | Body weight in UK/Ireland |
| 1 ounce (oz) | 0.02835 kg | Small ingredient weights, neonatal weight |
| 1 gram (g) | 0.001 kg | Drug mass, IV infusion amounts |
| 1 milligram (mg) | 0.000001 kg | Standard oral drug dose unit |
| 1 microgram (mcg) | 10⁻⁹ kg | Potent drugs: digoxin, fentanyl, levothyroxine |
Stone + Pounds Display
In the UK and Ireland, body weight is often expressed as a combination — e.g. "11 stone 4 pounds" (11 st 4 lbs). To convert: total pounds = (stone × 14) + remaining pounds, then multiply by 0.4536 to get kg. Our stone display shows the decimal stone value; for st + lbs format use: integer part = stone, remainder × 14 = pounds.
Note: For drug dosing, always use kg as the standard unit. The pound (avoirdupois) conversion factor is exactly 0.45359237 kg per NIST definition.