---
title: "Molecular Weight Calculator | Chemistry Formula Calculator | XTRAW Tools"
description: "Calculate molecular weight by summing atomic weights of constituent atoms. Use this free browser-based chemistry calculator from XTRAW Tools for lab, classroom, and STEM estimates."
url: "https://xtraw.com/calculators/science-calculators/chemistry-calculators/molar-mass-calculators/molecular-weight-calculator"
date: "2026-05-20T22:53:51+00:00"
language: "en-GB"
---

[Moles to Grams Calculator](https://xtraw.com/calculators/science-calculators/chemistry-calculators/molar-mass-calculators/moles-to-grams-calculator)[Equivalent Weight Calculator](https://xtraw.com/calculators/science-calculators/chemistry-calculators/molar-mass-calculators/equivalent-weight-calculator)

 [![Molecular Weight Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/xtraw-molecular-weight-calculator-360x360.jpg)](https://xtraw.com/images/virtuemart/product/xtraw-molecular-weight-calculator-360x360.jpg "Molecular Weight Calculator from XTRAW Tools")

  new

 [Back to: Molar Mass Calculators](https://xtraw.com/calculators/science-calculators/chemistry-calculators/molar-mass-calculators "Molar Mass Calculators")

# Molecular Weight Calculator

 Calculate molecular weight by summing atomic weights of constituent atoms. Use this free browser-based molecular weight calculator from XTRAW Tools.

 **Molecular Weight Calculator** helps you calculate molecular weight by summing atomic weights of constituent atoms. Use this free browser-based calculator from XTRAW Tools to compare inputs, estimate results, and plan your next step.

## How to Use the Molecular Weight Calculator

1. Enter the required calculator inputs shown in the form.
2. Review the molecular-weight, mass, yield, concentration, dilution, gas-law, or colligative-property assumptions.
3. Run the calculator, then adjust one input at a time to compare scenarios or check your estimate.

## What This Calculator Helps With

Calculate molecular weight by summing atomic weights of constituent atoms. It is designed for students, teachers, chemistry learners, lab users, healthcare reference users, STEM tutors, and anyone working with chemistry formulas who want a fast browser-based estimate before relying on a textbook, lab software, chemistry reference, professional source, or specialist.

- H atoms: 2 ×1.008
- C atoms: 0 ×12.011
- N atoms: 0 ×14.007
- O atoms: 1 ×15.999
- Na atoms: 0 ×22.990
- Cl atoms: 0 ×35.453
- Ca atoms: 0 ×40.078
- S atoms: 0 ×32.065
- P atoms: 0 ×30.974
- K atoms: 0 ×39.098

## Common Uses

People use this calculator when they need a quick way to estimate formula weight, molar mass, equivalent weight, or mole-particle relationships.

- **Math Solving:** Solve chemistry, concentration, stoichiometry, yield, gas-law, molecular-weight, or solution equations from entered values.
- **Measurement:** Measure molar mass, percent composition, yield, dilution, concentration, normality, particles, osmotic pressure, or boiling point changes.
- **Unit Conversion:** Convert chemistry quantities such as moles, particles, grams, concentration, and related formula values.

## Formula or Method

MW = Σ(nᵢ × atomic weightᵢ)

## Example

**Example inputs:** H atoms: 2 ×1.008; C atoms: 0 ×12.011; N atoms: 0 ×14.007; O atoms: 1 ×15.999; Na atoms: 0 ×22.990; Cl atoms: 0 ×35.453; Ca atoms: 0 ×40.078; S atoms: 0 ×32.065; P atoms: 0 ×30.974; K atoms: 0 ×39.098

**Example result:** Using the default atoms, molecular weight is about 18.015 g/mol.

## Related Tools

- [Moles To Grams Calculator](https://xtraw.com/tools/moles-to-grams-calculator)
- [Grams To Moles Calculator](https://xtraw.com/tools/grams-to-moles-calculator)
- [Molarity Calculator](https://xtraw.com/tools/molarity-calculator)
- [Equivalent Weight Calculator](https://xtraw.com/tools/equivalent-weight-calculator)
- [Avogadro's Number Calculator](https://xtraw.com/tools/avogadros-number-calculator)

## Molecular Weight Calculator FAQ

### Is the Molecular Weight Calculator free?

Yes. This calculator is free to use on XTRAW Tools.

### Do I need to create an account?

No. XTRAW tools are designed for browser-based use without requiring an account.

### Are the results exact?

Results may be estimates depending on the inputs, formula, rounding, chemistry reference values, assumptions, or purpose of the calculator. Always verify important results before relying on them.

**Disclaimer:** This calculator is provided for general informational, educational, and convenience purposes only. It is not medical, laboratory, chemical handling, safety, legal, financial, academic, regulatory, or professional advice. Always verify important results with a qualified professional, instructor, chemist, lab supervisor, safety documentation, authoritative source, or appropriate specialist before making decisions.

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