Convert Between Customary and Metric Weight/Mass
Converting between customary and metric weight and mass means using known conversion factors to switch between pounds/ounces and kilograms/grams. Key conversions: 1 kilogram = 2.2 pounds and 1 pound = 0.454 kilograms approximately. To convert 5 kg to pounds: 5 x 2.2 = 11 pounds. To convert 8 pounds to kilograms: 8 x 0.454 = 3.63 kg. This 6th grade measurement skill from enVision Mathematics Grade 6 is practically important for science, nutrition labels, international shipping, and any context where both measurement systems appear.
Key Concepts
Property To convert between customary and metric units of weight and mass, use the following approximate conversion factors: 1 ounce (oz) $\approx$ 28.35 grams (g) 1 kilogram (kg) $\approx$ 2.205 pounds (lb) 1 metric ton (t) $\approx$ 1.102 short tons (T).
Examples Convert 5 ounces to grams: $$ 5 \text{ oz} \times \frac{28.35 \text{ g}}{1 \text{ oz}} = 141.75 \text{ g} \quad \text{or} \quad 141.75 \text{ g} \times \frac{1 \text{ oz}}{28.35 \text{ g}} = 5 \text{ oz} $$.
Convert 3 kilograms to pounds: $$ 3 \text{ kg} \times \frac{2.205 \text{ lb}}{1 \text{ kg}} \approx 6.615 \text{ lb} \quad \text{or} \quad 6.615 \text{ lb} \times \frac{1 \text{ kg}}{2.205 \text{ lb}} \approx 3 \text{ kg} $$.
Common Questions
How do you convert kilograms to pounds?
Multiply the number of kilograms by 2.2. For 5 kg: 5 x 2.2 = 11 pounds. This approximation is accurate enough for most practical purposes.
How do you convert pounds to kilograms?
Multiply the number of pounds by 0.454 (or divide by 2.2). For 8 pounds: 8 x 0.454 = 3.63 kg.
How do grams relate to ounces?
1 ounce = 28.35 grams approximately. To convert ounces to grams, multiply by 28.35. For 4 oz: 4 x 28.35 = 113.4 g.
What grade learns to convert between customary and metric weight?
Converting between customary and metric weight is a 6th grade measurement skill in enVision Mathematics Grade 6, applying ratio and proportion to unit conversion.
Why do we need both customary and metric measurement systems?
The US uses customary units in everyday life (pounds, ounces), while most of the world and all of science uses metric (kilograms, grams). Knowing both is essential for real-world and scientific contexts.
How does converting weight use proportional reasoning?
The conversion factor is a unit rate. Setting up 2.2 lb / 1 kg = x lb / 5 kg is a proportion that can be solved with cross multiplication, giving x = 11 lb.