The conversion factor
One kilogram equals exactly 2.204623 pounds. For a body weight of 70 kg: 70 × 2.204623 = 154.323584 pounds (rounded to 6 decimal places).
The factor on its own
For a single kilogram, the factor itself is the answer: 1 kg = 2.204623 lb — worth memorizing directly, since so many everyday conversions (body weight, luggage limits, package weights) start from a kilogram figure.
Where the factor comes from
The pound is defined in terms of the kilogram (the SI base unit for mass): 1 pound equals exactly 0.45359237 kilograms by international agreement, and 2.204623 is the reciprocal of that — 1 ÷ 0.45359237.
Why the reverse conversion isn't quite as clean
Converting a weight already rounded to 2 decimal places in pounds back to kilograms doesn't always land exactly back where it started — a detail explored directly in the companion article on converting pounds to kilograms.