按 IUPAC 2023 原子量计算化学式的分子量。含括号的化学式。
Break the formula into elements and their counts. Handle parentheses, subscripts, and hydrates.
Use IUPAC standard atomic weights from the periodic table. Multiply each mass by its count.
Add up all element contributions. The result is the molecular weight in g/mol.
Type the formula using standard notation: H2O, C6H12O6, Ca(OH)2, CuSO4.5H2O. We parse parentheses, nested groups, and hydrates automatically.
For each element, we look up the standard atomic weight from the periodic table. The calculator also shows the count of each atom in the formula.
See the total molecular weight in g/mol plus a per-element breakdown. Useful for stoichiometry, solution preparation, and chemistry homework.
For related calculations, try our proportion calculator.
按 IUPAC 2023 原子量：
| 分子 | 化学式 | 分子量（g/mol） |
|---|---|---|
| 水 | H₂O | 18.015 |
| 氯化钠 | NaCl | 58.443 |
| 葡萄糖 | C₆H₁₂O₆ | 180.156 |
| 硫酸 | H₂SO₄ | 98.079 |
| 乙醇 | C₂H₅OH | 46.069 |
化学式大小写敏感（CO 是 C+O，但 Co 是钴）。同位素平均原子量（CIAAW 2023）。摩尔 = 分子量克数。1 mol = 6.022 × 10²³ 分子（Avogadro）。
Cross-checked against authoritative formulas (IRS, NIST, ACSM) and updated for 2025/2026 tax years and rates.
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A molecular weight calculator is a free chemistry tool that finds the molar mass of any chemical compound from its formula. Our molecular weight calculator uses the IUPAC standard atomic weights from the periodic table and supports parentheses, hydrates, and nested groups. The molecular weight calculator also shows the percent composition of each element.
How it works
Our molecular weight calculator lets you find the molar mass of any chemical compound from its formula, with full breakdown by element, in three steps.
Type the formula using element symbols and subscripts. Examples: H2O, C6H12O6, NaCl, H2SO4, Ca(OH)2, CuSO4.5H2O for hydrates. Element symbols are case-sensitive: Co is cobalt, CO is carbon monoxide. The Quick examples row gives common formulas.
Press Calculate. The result shows the molar mass in g/mol, the total number of atoms, and the count of unique elements. The breakdown card shows each element's count, mass contribution, and percent of the total mass.
Type a mass in grams to also see how many moles that mass represents. Useful for solution prep: enter 5 g to see 5/180.16 = 0.0277 mol of glucose. The share button creates a link with both the formula and the mass pre-filled.
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