高效準確的化學工具
Molar Mass & Mole Converter
輸入任意化學式即可計算其分子量、摩爾質量、元素質量百分比及原子個數，精確至4位小數。
118
118種元素
Nₐ
4位小數
100%
100% 本地運算
分子量
支援所有118種元素 · IUPAC 2021 標準原子量
快速範例:
在上方輸入化學式以計算分子量
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.