---
type: "WebPage"
title: "Analysis and measurement of molecular weight in the laboratory"
description: "Your needs: determining the size and weight of a molecule Molecular weight measurement in a nutshell... By definition, molecular mass is the mass of a single molecule of a substance. It is calculated by adding up the atomic masses of..."
resource: "https://filab.fr/en/our-services/our-analysis-services/chemical-analysis-laboratory/analysis-and-measurement-of-molecular-weight-in-the-laboratory/"
tags: ["EN", "pll_623affbb24624", "Anaïs DECAUX"]
timestamp: "2026-07-29T07:55:17Z"
published: "2022-06-15T14:07:41Z"
language: "en"
author: "bwa"
---

# Analysis and measurement of molecular weight in the laboratory

## Your needs: determining the size and weight of a molecule

### Molecular weight measurement in a nutshell...

By definition, molecular mass is the mass of a single molecule of a substance. It is calculated by adding up the atomic masses of all the atoms present in the molecule.

It can be considered equivalent to molar mass. However, molar mass is used for macroscopic samples in grams, whereas molecular mass refers to individual microscopic entities.

## Our solutions: offering molecular weight analysis techniques tailored to your needs and providing fast, reliable results

FILAB, an independent laboratory based in Dijon, supports you in your molecular weight measurement and analysis projects, to address your quality, safety, and performance challenges.

Our experts provide several molecular weight analysis and characterization services:

- [Determination of absolute molecular mass by GPC/SEC](https://filab.fr/nos-moyens-techniques/laboratoire-analysis-gpc-sec/)
- Determination of molecular mass distribution
- [Characterization of therapeutic peptides (GPL-1)](https://filab.fr/en/sectors-of-activity/biopharmaceutical/analytical-characterization-of-therapeutic-peptides-glp-1.md)
- Liquid chromatography analysis with [mass spectrometry detection (LC-MS)](https://filab.fr/nos-moyens-techniques/laboratoire-analysis-chromatographie-liquide-hplc/)
- Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)
- [Analytical Development and Validation](https://filab.fr/en/our-services/our-expertise-services/laboratory-analytical-method-validation.md)for the specific measurement of the molecular weight of your samples

### In what context is molecular mass measurement useful?

In the field of chemical substance analysis and characterization, knowledge of molecular weight is a key element in identifying the elemental composition of a product.

Each atom has specific properties such as density, melting point, or boiling point, but it is thanks to their**unique molecular mass**that we seek to identify and characterize them.

Molecular weight analysis and a solid understanding of the chemical elements making up your products will allow you to:

- Validate their compliance with your specifications and regulatory standards
- Adapt your production processes to avoid the risk of failure
- Study the compatibility of a chemical product with its environment

Different data between theoretical molecular mass and measured molecular weight may indicate potential non-compliance or failures.

## Our analytical capabilities

 [### HPLC-UV

High-performance liquid chromatography](https://filab.fr/en/our-technical-resources/laboratory-analysis-uplc/hplc-uv-analysis-laboratory.md) [### LC-HRMS

High-resolution mass spectrometry](https://filab.fr/en/our-technical-resources/lc-orbitrap-analysis.md) [### LC-HRMS/MS

LC-HRMS/MS tandem mass spectrometry (LC-Orbitrap)](https://filab.fr/en/our-technical-resources/high-resolution-mass-spectrometry-hrms-analysis.md) [### GPC](https://filab.fr/en/our-technical-resources/laboratory-analysis-gpc-sec.md)
## FAQ

 How do you differentiate molar mass from molecular mass?
For a given substance, molar mass and molecular mass are numerically equivalent, but they differ in their units and contexts of use. Molar mass is used for macroscopic samples in grams, whereas molecular mass refers to individual microscopic entities.

In short, while molecular mass focuses on the mass of a single molecule, molar mass relates to the mass of a large number of these molecules.

 What are the units of molecular weight measurement?
Its units are atomic mass units (u) or daltons (Da), where 1 u is approximately equal to the mass of a proton or a neutron.