As many prehospital providers in the United States know – you won’t always have a handy calculator or smartphone when trying to convert a patient’s weight from pounds to kilograms. Until the United States gets with the times and starts using the metric system like the rest of the world, you and your nursing staff will continue to convert weights for medication dosing.
We all learned the mathematical formula for the conversion:
lbs / 2.2 = kilograms kg x 2.2 = pounds
I would like to share a trick of the trade for new emergency providers – for those who are unable to quickly do the above conversions in their head especially under stressful situations.
1. Patient’s weight in lbs divided by 2 ie. 220 lbs / 2 = 110
2. 110 lbs – 11 = 99 (subtract the first 2 digits – if it’s a 3 digit number)
3. 220 lbs = 99 kg (within 1 kg) actual is 99.7 kg
If your patient weighs 80 lbs., then…
80 / 2 = 40.
40 – 4 = 36 (substract the first digit if it’s a 2 digit number.)
80 lbs = 36 kg
If you patient weighs 16 lbs., then…
16 / 2 = 8
8 – 0.8 = 7.2 kg (subtract 1/10th – just drop a decimal in front and subtract it from the original number if you’re dealing with a single digit.)
16 lbs = 7.2 kg
This trick of the trade will always work (within 1 kg) and is a quick and easy weight to convert lbs to kg even under stressful situations.
Check and see for yourself.[calc id=47]