Where weight conversions actually come up
Weight conversions are baked into every cross-border interaction: checked baggage limits (KLM 23 kg = 50.7 lb, near-identical to US domestic caps but not identical), fitness apps that were built for one system and used in another, US recipes that call for 8 oz of butter, medical dosages ("mg per kg body weight" for children — US pharma labels increasingly ship in both). The conversion factor (1 kg = 2.20462 lb) matters to two decimals for practical use.