You type a chemical formula using standard notation — uppercase for the first letter of each element, lowercase for the second (if any), and numbers for subscripts. The parser walks through the string character by character, handles parenthesized groups recursively, and looks up each element's standard atomic weight from IUPAC 2021 values. It multiplies weight by atom count and sums the totals. Elements not in the built-in table will return "Invalid."
It includes the most common elements: H, C, N, O, Na, Cl, S, P, Fe, Ca, K, Mg, B, F, Br, I, Si, Al, Cr, Mn, Cu, Zn, Ar, and Ne. If you need a less common element, the calculator will return "Invalid" — you can compute it manually using IUPAC atomic weight tables.
Type parentheses directly — for example, Ca(OH)2 for calcium hydroxide or Al2(SO4)3 for aluminum sulfate. The parser handles nested groups automatically. No subscript formatting is needed; just use regular numbers.
The calculator uses standard atomic weights rounded to 2–3 decimal places, which is accurate enough for most educational and general chemistry purposes. For research-grade precision, consult the IUPAC Commission on Isotopic Abundances and Atomic Weights.
Molecular weight applies to covalent compounds that exist as discrete molecules (like H₂O). Formula weight applies to ionic compounds (like NaCl) that form lattice structures rather than individual molecules. Numerically, the calculation is the same — sum of atomic weights times atom counts.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.