Pounds to Kilograms Converter

The box takes one number, so the ounces have to become a fraction of a pound. The quickest way is to type them over 16 as a mixed number, with a space after the pounds: 7 8/16 for 7 lb 8 oz. Working it out by hand gives the same thing:

• 7 lb 8 oz is 7 + 8/16 = 7.5 lb, which converts to 3.4019 kg.
• 8 lb 8 oz is 8.5 lb, or 3.8555 kg.

Typing 7.8 for "7 lb 8 oz" is the usual slip. 7.8 lb is 3.538 kg, about 136 g more than the real weight, because 0.8 lb is 12.8 oz, not 8. For a newborn, a parcel or a cut of meat that difference matters.

Leave the unit out. Pasting "150 lbs" or "lbs 150" brings up a note that the number couldn't be read, while plain 150 converts to 68.0389 kg.

A 45 lb plate is 20.4117 kg, not 20 kg. The gap is 0.41 kg per plate, so four of them make 180 lb, or 81.6466 kg, against 80 kg for four 20 kg plates. If you train in two gyms that use different units, convert the total load, then round to what the other gym's plates can actually make.

Smaller plates drift the same way: 35 lb is 15.8757 kg and 25 lb is 11.3398 kg. A pair of 10 lb dumbbells is 4.5359 kg each.

For body weight on a form that asks for kilograms with one decimal, round the result: 165 lb is 74.8427 kg, so write 74.8.

Two shortcuts get you close without a calculator. Here they are against the converter's result:

Halving and then subtracting a tenth multiplies by 0.45. It is the easiest to do in your head but runs about 0.79% low, which is half a kilogram at 150 lb. Dividing by 2.2 is harder to do mentally but only 0.21% high.