高效准确的化学工具
Molar Mass & Mole Converter
输入任意化学式即可计算其分子量、摩尔质量、元素质量百分比及原子个数，精确至4位小数。
118
118种元素
Nₐ
4位小数
100%
100% 本地运算
分子量
支持所有118种元素 · IUPAC 2021 标准原子量
快速示例:
在上方输入化学式以计算分子量
Step-by-Step Guide
How to Calculate Molecular Weight
Calculate chemical formula mass in three simple steps.
Input a Chemical Formula
Type any chemical formula — H₂O, C₆H₁₂O₆, NaOH, or even complex structures with parentheses and brackets. The molar mass calculator identifies each element, resolves nested groups, and counts every atom. All 118 elements from the periodic table are supported.
NaOH
↓
Na × 1O × 1H × 1
FAQ
Frequently Asked Questions
Find answers to common questions about molecular weight calculations and chemistry formulas.
Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol).
To calculate molar mass: (1) identify each element in the formula, (2) look up each element's standard atomic weight from the IUPAC periodic table, (3) multiply each atomic weight by its atom count, and (4) sum all products.
The Avogadro constant (Nₐ) is exactly 6.02214076 × 10²³ mol⁻¹, as defined by the 2019 redefinition of SI units.
Use the formula: moles = mass (g) ÷ molar mass (g/mol).
Numerically, yes — molar mass and molecular weight have the same value.
Ionic compounds like NaCl don't form discrete molecules, so technically we use 'formula mass' rather than 'molecular mass.' However, the molar mass calculation is identical: sum the atomic weights of all atoms in one formula unit.
This calculator provides molar mass values to 4 decimal places using IUPAC 2021 standard atomic weights.