Metric Math

By Joan Whetzel

The metric system, or International System (SI) of measurement was first adopted in France at the end of the 18th century. Since then it has been adopted by most countries around the world with the exclusion of the US, Liberia, Burma and to some extend Great Britain. Several organizations and government agencies have attempted to convert the US to the metric system since the mid-19th century. The only place where the US accepts the metric system completely is in the scientific community because the measurements are more accurate, which increases the likelihood of replicating the results of experiments.

Today, in the US, most food and product packaging list both the English and the metric measurements and other measuring devices – measuring cups, rulers, measuring tapes, etc. – have both English and metric measurements as well. Below are listed a description of the metric prefixes and what they mean, conversion tables between the English and metric systems, and descriptions of the metric system uses for measuring volume, length and weight.

Metric Prefixes

The metric system began with one basic unit – the meter – defined as “the distance light travels in a vacuum in 1 / 288,792,458 of a second.” It developed into a decimalized system of measurement founded on a set of base units: the liter for volume, the meter for length, and the gram for weight. The table below illustrates how adding each prefix increases or decreases the base unit by powers of ten.

Metric Volume

Liquids are measured with graduated cylinders calibrated to the metric system for lab work, or in the kitchen, with measuring cups which calibrated to both English and metric measurements (at least in the US), and measuring spoons calibrated to English measurements. First examine the measuring cup or graduated cylinder to discern what measurement each line or mark stands for. Next determine the liquid volume by sighting where the liquid lines up with the English/metric scale mark on the measuring cup or graduated cylinder. Unfortunately, surface tension causes the fluid surface to appear curved upward, which is more pronounced in the narrow tube of the graduated cylinder. To be certain the measurement is correct, line up the meniscus (the lower edge of the fluid surface) with the marking.