Empirical Formula Calculator
Empirical Formula Calculator
Enter the mass percentage of each element in your compound. This calculator converts each percentage to moles (using a 100 g sample), divides every mole value by the smallest one, and rounds to the nearest whole number to get the simplest ratio - the empirical formula.
Assuming a 100 g sample is a convenient trick that turns each percentage directly into a mass in grams without changing the underlying ratio — from there, dividing each element's mass by its atomic mass converts it to moles, and dividing every mole value by whichever one is smallest reveals the simplest whole-number ratio between elements. It's worth remembering that the empirical formula only shows this simplest ratio, not necessarily the compound's true molecular formula: glucose's empirical formula is CH₂O, but its actual molecular formula is C₆H₁₂O₆ — six times larger, but the same underlying 1:2:1 ratio.
- The empirical formula shows the simplest whole-number ratio of atoms, not necessarily the true molecular formula - glucose's empirical formula is CH₂O, but its molecular formula is C₆H₁₂O₆.
- The method: assume a 100 g sample, so each percentage becomes a mass in grams, divide by atomic mass to get moles, then divide all mole values by the smallest one.
- Use the Molecular Formula Calculator afterward if you also know the compound's actual molar mass, to scale the empirical formula up to the true molecular formula.
How do I find the empirical formula from percent composition?
Convert each percentage to moles by dividing by that element's atomic mass, then divide all the mole values by the smallest one and round to whole numbers.
What is the empirical formula for 40% C, 6.7% H, 53.3% O?
This is the classic textbook example: it gives CH₂O (the empirical formula shared by glucose, formaldehyde, and other carbohydrates).
Empirical Formula Calculator
Enter the mass percentage of each element in your compound. This calculator converts each percentage to moles (using a 100 g sample), divides every mole value by the smallest one, and rounds to the nearest whole number to get the simplest ratio - the empirical formula.
Assuming a 100 g sample is a convenient trick that turns each percentage directly into a mass in grams without changing the underlying ratio — from there, dividing each element's mass by its atomic mass converts it to moles, and dividing every mole value by whichever one is smallest reveals the simplest whole-number ratio between elements. It's worth remembering that the empirical formula only shows this simplest ratio, not necessarily the compound's true molecular formula: glucose's empirical formula is CH₂O, but its actual molecular formula is C₆H₁₂O₆ — six times larger, but the same underlying 1:2:1 ratio.
- The empirical formula shows the simplest whole-number ratio of atoms, not necessarily the true molecular formula - glucose's empirical formula is CH₂O, but its molecular formula is C₆H₁₂O₆.
- The method: assume a 100 g sample, so each percentage becomes a mass in grams, divide by atomic mass to get moles, then divide all mole values by the smallest one.
- Use the Molecular Formula Calculator afterward if you also know the compound's actual molar mass, to scale the empirical formula up to the true molecular formula.
How do I find the empirical formula from percent composition?
Convert each percentage to moles by dividing by that element's atomic mass, then divide all the mole values by the smallest one and round to whole numbers.
What is the empirical formula for 40% C, 6.7% H, 53.3% O?
This is the classic textbook example: it gives CH₂O (the empirical formula shared by glucose, formaldehyde, and other carbohydrates).