Empirical Formula Calculator

• Pick Mass (g) or Percent mode.
• Add each element (symbol) and its value.
• Click Calculate to get the empirical formula and a mole-ratio table.
• If needed, we scale ratios to the nearest whole numbers (like ×2 for 1.5).

• Convert each entry to moles: moles = grams / atomic mass.
• Divide all moles by the smallest mole value to get ratios.
• Find a small multiplier (×1..×12) that turns ratios into near integers.
• Format the formula with subscripts (e.g., C₆H₁₂O₆).

Example 1 — Percent composition of glucose

1. Assume 100 g: C=40.00 g, H=6.71 g, O=53.29 g.
2. Convert to moles: C≈3.33, H≈6.66, O≈3.33.
3. Divide by smallest (3.33): C=1, H=2, O=1 → CH₂O.

Example 2 — Percent composition of carbon dioxide (CO₂)

1. Assume 100 g: C=27.29 g, O=72.71 g.
2. Convert to moles: C≈27.29/12.01≈2.27, O≈72.71/16.00≈4.54.
3. Divide by smallest (2.27): C=1, O=2 → CO₂.

Example 3 — Mass data (iron oxide)

1. Given masses: Fe=111.69 g, O=48.00 g.
2. Convert to moles: Fe≈111.69/55.85≈2.00, O≈48.00/16.00=3.00.
3. Divide by smallest (2.00): Fe=1, O=1.5 → multiply by 2 → Fe=2, O=3.
4. Empirical formula: Fe₂O₃.