Weight Converter

How the Weight Converter Works

Every unit is converted through a single base unit — the gram. The tool first converts your input to grams using a fixed factor, then divides by the factor for your target unit. For example, converting 5 pounds to kilograms goes 5 lb × 453.592 = 2267.96 g, then 2267.96 ÷ 1000 = 2.268 kg. Routing everything through one base unit keeps every conversion consistent and reversible.

Metric vs Imperial Units

The metric system (mg, g, kg, tonne) scales in powers of ten, so 1 kg = 1,000 g = 1,000,000 mg. The imperial and US customary system (oz, lb, stone, ton) uses fixed but irregular ratios: 1 lb = 16 oz, 1 stone = 14 lb, 1 short ton = 2,000 lb. Because the ratios differ, mixing systems by hand is error-prone — the exact anchor 1 inch = 2.54 cm has a weight analogue in 1 lb = 453.59237 g, which this tool uses for precision.

Common Real-World Conversions

Cooking recipes often list 1 oz (28.35 g) or 1 lb (454 g) of an ingredient. Shipping and postage bounce between grams and ounces. Bodyweight is quoted in kg in most of the world, in stone-and-pounds in the UK, and in pounds in the US: 80 kg is about 176 lb or 12 st 8 lb. Gym plates are sold in both 20 kg and 45 lb versions, which are close but not identical (45 lb = 20.4 kg).

Avoiding Rounding Errors

When you chain conversions — say grams to ounces to pounds — rounding at each step compounds the error. This converter always calculates from the original value through grams in one pass, then rounds only the final displayed result. For scientific or trade work where every digit matters, keep the full-precision output rather than the rounded figure, since 1 kg is 2.20462 lb, not simply 2.2 lb.