What is MolCalc?

MolCalc is a web interface that allows chemist to build small molecules and estimate molecular properties such as

in a matter of seconds or minutes - depending on the size.

Disclaimer: MolCalc is designed for teaching as opposed to research - specifically for assignments in which students build their own molecules and estimate their own molecular properties. It is designed to run fast and therefore estimated molecular properties will not match experimental values exactly, and in some cases be quite different.

The idea is to have students develop a "chemical intuition" about how molecular structure affects molecular properties, without performing the underlying calculations by hand (which would be near impossible for all but the simplest chemical systems).

How do I cite MolCalc?

J. H. Jensen and J. C. Kromann,
The Molecule Calculator: A Web Application for Fast Quantum Mechanics-Based Estimation of Molecular Properties,
J. Chem. Educ., 2013, 90 (8), pp 1093–1095. DOI: 10.1021/ed400164n

How does MolCalc work?

For 2D compound building, we use the excellent from Chemdoodle.

MolCalc uses the following technologies

Other than standard HTML and CSS3 we use the following technologies and packages.

Frontend uses

Backend uses

Can I host my own version MolCalc?

Yes, MolCalc is distributed through GitHub under the MIT license. Download and the source from

For the quantum chemistry calculations you must obtain a copy of the GAMESS code separately from

Installation and dependencies

Check out for installation guide.

I found a bug or I have a feature request

want to contribute? Want to extend the functionality of molcalc? Great. Please report it at