CONVERT Area Bits & Bytes Density Energy Force Length Mass Power Pressure Speed Temperature Volume Mass or weight Input carats (metric) Earth masses grains grams hudredweights (long) hudredweights (short) kilograms [kg] ounces (avoirdupois) ounces (troy) pounds (avoirdupois) pounds (troy) Solar masses slugs (g-pounds) stones tons (UK or long) tons (US or short) tonnes Output carats (metric) Earth masses grains grams hudredweights (long) hudredweights (short) kilograms [kg] ounces (avoirdupois) ounces (troy) pounds (avoirdupois) pounds (troy) Solar masses slugs (g-pounds) stones tons (UK or long) tons (US or short) tonnes The SI unit for mass is the kilogram. UK and US use the Avoirdupois system of weights. The Troy system of weights is used in England for gold, silver and precious stones.