By Jessica Reed
Updated Aug 30, 2022
Converting measurements is a core skill in high‑school math and science—and a prerequisite for many college courses. Mastering the metric system, especially if you grew up using U.S. customary units, can seem daunting. However, the Stair‑Step Method offers a clear, visual way to convert any metric prefix—kilometers to centimeters, milliliters to liters, and more—without endless multiplication.
On a sheet of paper, sketch seven horizontal steps. Begin at the top and label each step with the metric prefixes in order: K (kilo-), H (hecto), D (deca), O (origin/base unit), d (deci), C (centi), and M (milli). These are the building blocks of metric conversions.
Each prefix pairs with a base unit. For example, kilo- can represent kilograms or kilometers; centi- can represent centimeters or centiliters. The “origin” step (O) is the unit without a prefix—such as meter, gram, or liter—depending on what you’re converting.
Identify the step that corresponds to the unit you’re converting from, and the step that corresponds to the unit you’re converting to. Count how many steps you move, excluding the starting step.
Take the numerical value and shift the decimal point one place for each step you move. Moving up the stairs (toward larger prefixes) increases the value; moving down decreases it.
Start on the “Milli” step and move up to the “Origin” step (liters). That’s three steps. Move the decimal in 4 three places to the left: 4 → 0.4 → 0.04 → 0.004. Thus, 4 mL equals 0.004 L.
The mnemonic “Kids Have Dropped Over dead Converting Metrics” helps remember the order: K, H, D, O, d, C, M. The second D is deci, and O stands for Origin. With practice, you’ll perform conversions mentally—moving backwards shrinks the number, moving forwards enlarges it.
