Find the simplest whole-number element ratio
An empirical formula states the smallest whole-number ratio of elements in a compound. Enter each element symbol and its positive mass or mass percentage on a separate row. The calculator divides every value by that element’s conventional atomic weight, normalizes the resulting mole amounts by the smallest, and searches multipliers from one to twelve for a defensible whole-number ratio.
The default carbon, hydrogen, and oxygen percentages produce the ratio 1:2:1 and the empirical formula CH2O. Percentages work because a hypothetical 100-unit sample turns each percentage into the same number of mass units. Absolute masses also work because multiplying every entered mass by one common factor does not change the normalized mole ratios.
Convert mass to moles before comparing elements
Masses cannot be compared directly because atoms of different elements have different masses. Divide each element mass by its atomic weight to obtain relative moles. Then divide all mole values by the smallest positive mole value. This makes the smallest ratio one and reveals whether the other values are near integers or familiar fractions.
A ratio near 1.5 suggests multiplying all ratios by two; a ratio near 1.333 suggests multiplying by three. The calculator tries the smallest multiplier that brings every value within 0.03 of a whole number, up to twelve. It reports the multiplier and maximum deviation so rounding is visible rather than forcing any decimal pattern into a plausible-looking formula.
Enter clean element rows and adequate precision
Each row uses element symbol, value, for example C, 40.00. Symbols are case-sensitive and each element may appear only once; combine repeated measurements before entry. Values must be positive finite decimals or scientific notation. Two to twelve elements are accepted. Percent values need not total exactly 100 because the method uses relative amounts, but an unmeasured element can still make the inferred formula chemically incomplete.
Keep more digits than the final reported composition whenever possible. Prematurely rounded percentages can move a ratio just outside a small-integer tolerance or favor the wrong multiplier. If no multiplier through twelve fits, the page stops and asks for better data rather than choosing large arbitrary subscripts. Review the analytical precision, element identities, and possibility of a mixture or hydrate.
Check and interpret an empirical formula
Confirm that the reported integer subscripts share no common divisor greater than one. Multiply each subscript by its atomic weight to obtain predicted mass contributions, then convert those contributions back to percentages and compare them with the source data within its uncertainty. This reverse check is stronger than accepting ratios merely because they look close to integers.
An empirical formula is not necessarily a molecular formula. Glucose and formaldehyde both reduce to CH2O even though their molecular formulas differ. Molecular formula requires molar mass or another measurement: divide molecular molar mass by empirical-formula mass to find an integer multiplier. Ionic compounds are commonly written as empirical formula units, while molecular substances may need the additional step.
Data limits and private calculation
The calculator assumes the entered rows describe one compound and that all relevant elements have been measured. It does not correct for sample moisture, oxygen gained during analysis, impurities, combustion-analysis biases, isotope enrichment, or measurement uncertainty. Experimental identification requires suitable analytical evidence and chemical judgment beyond a ratio calculation.
The values are calculated in the current browser tab. NexaCurrent does not upload the quantities, formulas, chemical names, element choices, or other information entered here, and no account is needed. Copying is a deliberate action after the answer and working are visible. Refreshing or leaving the page clears the current calculation, so keep a copied result if it is needed for later study.