About the Empirical Formula Calculator
Finds a compound's empirical (and optional molecular) formula from percent composition or mass data.
What it is
Enter each element's percent composition or measured mass, and the calculator converts every value to moles, divides by the smallest mole value, and simplifies to the lowest whole-number ratio — showing each intermediate step.
Features
Two input modes
Percent composition (validated against 100%) or raw mass data with any number of rows.
Atomic weight lookup
A built-in table of common elements; unrecognized symbols are flagged.
Mole-ratio derivation
Each step — moles, division by smallest, and any multiplier applied — is shown explicitly.
Non-integer ratio handling
Ratios like x.5 are cleared by multiplying by the correct small integer, explained in the working.
Optional molecular formula
Supply a known molar mass to derive the full molecular formula from the empirical result.