How we calculate

The same engine powers the live calculator and every compound profile. It parses chemical formulas, expands parentheses, multiplies atomic masses by atom counts, and sums the contributions.

Reference standards

• Atomic masses from our site periodic table (standard atomic weights for education).
• Parentheses multiply the enclosed group: Ca(OH)₂ → Ca + 2 O + 2 H.
• Results display in g/mol with three decimals on profiles for transparent arithmetic.

Worked micro-example

Water H₂O: (2 × 1.008) + 15.999 = 18.015 g/mol. Oxygen contributes most of the mass even though hydrogen atoms are more numerous—mass percent is not the same as atom percent.

Learn the pedagogy in How to calculate molar mass and browse the Top 50 library.