Molecular Weight Calculator

Welcome to the Molecular Weight (Molar Mass) Calculator, a user-friendly, web-based tool designed to help you quickly and accurately determine the molecular weight of any chemical compound.

How to Calculate Molecular Weight

Molecular weight, also known as molecular mass or molar mass, is the total mass of all atoms present in a molecule, expressed in atomic mass units (amu) or grams per mole (g/mol). To calculate the molecular weight of a compound, follow these steps:

1. Identify the chemical formula of the compound.
2. Determine the number of atoms for each element present in the formula.
3. Look up the atomic weight of each element on the periodic table.
4. Multiply the atomic weight of each element by the number of atoms of that element in the compound.
5. Add up the products obtained in the previous step to obtain the molecular weight of the compound.

Our Molecular Weight Calculator automates this process, allowing you to input the chemical formula and instantly receive the molecular weight of the compound.

Examples of Molecular Weight Calculations

Here are two examples to help you understand how molecular weight calculations work:

Example 1: H2O (Water)

For water (H2O), we have two hydrogen atoms (H) and one oxygen atom (O). The atomic weight of hydrogen is approximately 1.008 amu, and the atomic weight of oxygen is approximately 15.999 amu. To calculate the molecular weight of water:

1. Multiply the atomic weight of hydrogen (1.008 amu) by the number of hydrogen atoms (2): 1.008 amu x 2 = 2.016 amu
2. Multiply the atomic weight of oxygen (15.999 amu) by the number of oxygen atoms (1): 15.999 amu x 1 = 15.999 amu
3. Add the products obtained in steps 1 and 2: 2.016 amu + 15.999 amu = 18.015 amu

Therefore, the molecular weight of water (H2O) is approximately 18.015 amu or 18.015 g/mol.

Example 2: CO2 (Carbon Dioxide)

For carbon dioxide (CO₂), we have one carbon atom (C) and two oxygen atoms (O). The atomic weight of carbon is approximately 12.011 amu, and the atomic weight of oxygen is approximately 15.999 amu. To calculate the molecular weight of carbon dioxide:

1. Multiply the atomic weight of carbon (12.011 amu) by the number of carbon atoms (1): 12.011 amu x 1 = 12.011 amu
2. Multiply the atomic weight of oxygen (15.999 amu) by the number of oxygen atoms (2): 15.999 amu x 2 = 31.998 amu
3. Add the products obtained in steps 1 and 2: 12.011 amu + 31.998 amu = 44.009 amu

Therefore, the molecular weight of carbon dioxide (CO₂) is approximately 44.009 amu or 44.009 g/mol.

Using the Molecular Weight Calculator

To use our Molecular Weight Calculator, simply enter the chemical formula of the compound you wish to analyze in the designated input field. The calculator will automatically compute the molecular weight based on the atomic weights of the constituent elements and display the result in both amu and g/mol. This tool not only saves time but also minimizes the risk of calculation errors, making it a valuable resource for anyone working with chemical compounds.

Element Molar Mass Table

Simple Molecules Molar Mass Table

Acids Molar Mass Table

Bases Molar Mass Table

Complex Organic Compounds Molar Mass Table