Online molar mass - molecular weight calculator (MW) for any chemical formula such as H2O, CaCO3 ….
It has a built-in case correction so you could write h2o when you mean H2O
It also can be used for multi section formula Co3[Fe(CN)6]2 . 4NH3 . 6H2O Chemical Formula: is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses Empirical formula: In chemistry, the empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound Mole in chemistry: The mole (symbol: mol) is the base unit of amount of substance ("number of substance") in the International System of Units or System International (SI), defined as exactly 6.022 140 76 × 10^23 particles of entities (atoms, molecules, ions or electrons ...)