In English following Spain and Portugal's adoption of the metric system, the toneladas are most often used to specify the capacity of Spanish and Portuguese ships during the Age of Exploration with greater care than simply using the misleadingly vague calque "ton".
The Spanish tonelada of volume was reckoned as 2 butts or pipes (botas or pipas) and equivalent to 968.2 liters or 255.8 gallons.
[2] The Spanish tonelada of shipping capacity varied in size and method of computation over the years but scholars place the usual value for southern Spain from Columbus[3] through the Age of Exploration at about 1.42 m3 or 50.1 cu.
[9] The Portuguese tonelada of volume was initially reckoned as 2 pipes (pipas), which in the 19th century was equivalent to 860.3 liters or 226.3 gallons.
[10] The arratel was standardized in Portugal and Brazil as about 460 grams by the 19th century, producing a lighter tonelada of around 793.2 kilograms or 1748.5 pounds avoirdupois and a heavier one around 1028.2 kg and 2266.7 lbs.