Weight Converter
Weight conversion translates an amount of mass from one unit into another, so a value measured in kilograms can be expressed in pounds, grams, ounces, or tons. In everyday language "weight" and "mass" are used interchangeably, even though scientists distinguish mass (the amount of matter in an object) from weight (the force gravity exerts on that mass). For converting between units, the everyday meaning is what matters, since both systems describe the same quantity.
Popular Weight Conversions
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People convert weight constantly. You might read a recipe written in grams while shopping where food is sold in ounces, check whether a suitcase is under an airline's kilogram limit, compare a body weight given in pounds, or scale an industrial shipment quoted in metric tons. Because the metric and imperial systems are both in wide use, a reliable converter removes the guesswork.
Weight Units Explained
The metric units form a decimal ladder: 1 microgram (mcg) = 0.001 milligram (mg), 1 mg = 0.001 gram (g), 1 g = 0.001 kilogram (kg), and 1 metric ton (tonne) = 1,000 kg. Each step up is a factor of 1,000. The imperial and US customary units relate by whole numbers: 1 pound (lb) = 16 ounces (oz), and 1 short ton (the US ton) = 2,000 lb. The two systems link through one exact definition: 1 lb = 0.45359237 kg. From that single anchor every other metric-to-imperial weight conversion follows, including 1 oz = 28.349523125 g.
How to Convert Weight Units
The reliable method is to convert through a common base unit, usually grams or kilograms. First express the value in the base unit, then divide by the size of the target unit. The key exact factors are 1 lb = 0.45359237 kg and 1 oz = 28.349523125 g, plus the metric steps of 1,000. For quick mental math, 1 kg is about 2.20462 lb and 1 oz is about 28.35 g. Example: convert 150 lb to kg by multiplying 150 by 0.45359237, which gives 68.0388555 kg, or about 68.04 kg. Going the other way, convert 5 kg to pounds by dividing 5 by 0.45359237 (the same as multiplying by 2.20462), giving about 11.02 lb. To convert 250 g to ounces, divide 250 by 28.349523125 to get about 8.82 oz.
Common Uses
- Cooking and baking with recipes that mix grams and ounces
- Checking luggage against airline weight limits in kg or lb
- Tracking body weight across pounds and kilograms
- Reading medication or supplement doses in mg and mcg
- Pricing and shipping freight quoted in metric or short tons
- Comparing product net weights between metric and imperial labels
Accuracy Tips
Watch the difference between the short ton (2,000 lb, about 907.18 kg) and the metric ton (1,000 kg, about 2,204.62 lb); they are not the same. Keep mg and mcg straight, since confusing them shifts a dose by 1,000 times. Round only at the final step to avoid compounding errors, and remember that ounces of weight differ from fluid ounces of volume.
Frequently Asked Questions
How many grams are in a pound?
One pound equals exactly 453.59237 grams, because 1 lb is defined as 0.45359237 kg. People often round this to 453.6 g or, more loosely, about 454 g.
How many pounds are in a kilogram?
One kilogram is about 2.20462 pounds. So 70 kg is roughly 154.32 lb. To go from kg to lb, multiply by 2.20462; to go from lb to kg, multiply by 0.45359237.
How many ounces are in a pound?
There are exactly 16 ounces in a pound. One avoirdupois ounce equals 28.349523125 grams, so a pound is 16 times that, or 453.59237 grams.
What is the difference between a metric ton and a short ton?
A metric ton (tonne) is 1,000 kilograms, about 2,204.62 pounds. A short ton, the common US ton, is 2,000 pounds, about 907.18 kilograms. A metric ton is roughly 10 percent heavier than a short ton.
What is the difference between mg and mcg?
A milligram (mg) is 1,000 micrograms (mcg), so 1 mcg = 0.001 mg. This matters most for medications and supplements, where mistaking one for the other changes the amount by a factor of 1,000.