How it works
Every unit is a size in SI
Each unit is stored as its size in the category’s SI unit: a banana is 0.18 m long, a Big Mac holds 2.3 MJ, a Warhol lasts 900 seconds. Converting multiplies by the size of the unit you start from and divides by the size of the one you want.
Count units (dozen, gross, ream, mole, googol) are plain numbers, so they have no SI unit beside them.
amount in B = amount in A × size of A ÷ size of B
Reading the list
Every unit of the category is listed from smallest to largest, with how big one of it is and how many of it make up your amount. The bar shows the unit’s own size on a logarithmic scale, because a category can run from a Planck time to the age of the universe.
Pick a row to measure in that unit instead: the amount changes so the size stays the same. Results keep four significant digits; very small or very large ones switch to scientific notation.
Where the sizes come from
Defined units (furlong, fathom, BTU, horsepower) use their defined values. Objects and animals use typical sizes, such as an average adult or a common model, so treat them as round figures for a sense of scale, not as measurements.
