Chemistry

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Empirical Formula Calculator.

Calculate normalized C/H/N/O/X mole ratios from entered elemental masses and atomic masses.

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Set your values

Results update as you type.

molesCarbon: 1.998168

molesCarbon

1.998168
molesHydrogen: 3.968254

molesHydrogen

3.968254
molesNitrogen: 0.9995

molesNitrogen

0.999500
molesOxygen: 1.000063

molesOxygen

1.000063
molesHalogen: 0

molesHalogen

0.000000
ratioCarbon: 1.999167

ratioCarbon

1.999167
ratioHydrogen: 3.970238

ratioHydrogen

3.970238
ratioNitrogen: 1

ratioNitrogen

1.000000
ratioOxygen: 1.000563

ratioOxygen

1.000563
ratioHalogen: 0

ratioHalogen

0.000000

How to Use

Moles = entered mass ÷ entered atomic mass; each non-zero amount is divided by the smallest mole amount. X is one aggregate halogen slot.

All material properties and conventions are entered explicitly. Results update automatically; no chemical database or laboratory procedure is inferred.

Use Cases

Determine empirical formula from experimental data

Use this calculator to convert elemental mass percentages or masses into mole ratios, helping you find the simplest formula of a compound.

Example: If you have 2.0 g C, 0.5 g H, and 1.33 g O, enter these masses and atomic masses to get CH2O.

Check stoichiometry in chemistry homework

Quickly verify your manual calculations for empirical formulas, saving time and reducing errors in lab reports or assignments.

Example: For a compound with 40% C, 6.7% H, and 53.3% O, enter masses as 40, 6.7, 53.3 (assuming 100g sample) to get CH2O.

Frequently Asked Questions

How do I use the empirical formula calculator?
Enter the mass of each element (C, H, N, O, X) and its atomic mass. The calculator computes the mole ratio by dividing mass by atomic mass, then normalizes by the smallest mole value to give the empirical formula.
What does 'normalized' mean in the output?
Normalized means the mole ratios are divided by the smallest ratio so that the smallest becomes 1. This gives the simplest whole-number ratio of atoms, which is the empirical formula.
Can I use this calculator for any element?
Yes, the calculator includes fields for carbon (C), hydrogen (H), nitrogen (N), oxygen (O), and an 'X' field for any other element. Enter the mass and atomic mass for each element present in your sample.

Tips & Common Mistakes

Tips

  • Ensure all masses are in the same unit (e.g., grams) before entering them.
  • Use accurate atomic masses from the periodic table for precise results.
  • If you have a percentage composition, assume a 100 g sample and enter the percentages as masses.
  • Double-check that you've entered the correct atomic mass for each element, especially for the 'X' field.

Common Mistakes to Avoid

  • Forgetting to convert percentages to masses when using percent composition data.
  • Entering atomic masses incorrectly, such as using mass numbers instead of atomic weights.
  • Not normalizing the mole ratios manually, but the calculator does this for you, so avoid dividing by the wrong value.

Last updated: August 13, 2026