Free Chemical Structure Drawer
Chemical Structure Drawer lets you draw a molecule, or load it from SMILES, a Molfile or a common name, and calculates its formula, molecular weight, cLogP, polar surface area and Lipinski rule-of-five check. It exports SMILES, .mol, SVG and PNG, builds 3D models and opens PDB, SDF, MOL2 and XYZ files in a 3D viewer.
- Properties:
- Formula, MW, cLogP, TPSA, Lipinski
- Exports:
- SMILES, Molfile, SVG, PNG
- 3D files:
- PDB, SDF, MOL2, XYZ, mmCIF, PQR
- Price:
- Free
- Runs:
- Locally, in your browser
- Uploads:
- None: files never leave your device
- Account:
- Not needed
Quick answers
Is anything sent to a server?
No. Drawing, SMILES conversion, property calculation and 3D model generation all run in your browser, and names are looked up in a list built into the page.
How accurate are logP and solubility?
They are fast estimates from atom and fragment increments (OpenChemLib's cLogP and cLogS), good for comparing molecules and for rule-of-five screening, not a replacement for measured values.
Processed on your device: your files are never uploaded. How it works
Network activity in this tab
What this page has requested since you opened the site in this tab. An upload is any request that sends data: POST, PUT, PATCH or a request with a body.
No uploads: nothing has been sent from this page.
No network requests yet.
To see every request, open your browser's developer tools (Network tab).
How to use the Chemical Structure Drawer
- Draw a molecule with the tools on the left of the canvas, or type a name (caffeine, aspirin…), a SMILES string or paste a Molfile and press Load.
- Read the formula, molecular weight, exact mass, logP, solubility, polar surface area, hydrogen-bond counts and the Lipinski rule-of-five check, updated as you draw.
- Copy the SMILES or Molfile, or download the structure as .mol, SVG or PNG.
- Press View in 3D for a 3D model, or open a PDB, SDF, MOL2 or XYZ file in the 3D viewer; use the Molecular weight tab to compute the mass of any formula.
Credits & open source
Our own code plus open-source libraries. Thank you to the people who make these projects.
- OpenChemLib JSMolecule editor, SMILES/Molfile I/O and property calculation (formula, mass, logP). © cheminfo (Michaël Zasso); OpenChemLib by Idorsia Pharmaceuticals (Thomas Sander) · BSD-3-Clause
- 3Dmol.jsMolecular 3D viewer (PDB, SDF, MOL2…). © University of Pittsburgh and contributors (David Koes) · BSD-3-Clause
- pubchem-elementsPeriodic table data from PubChem (US government work, public domain). © Kai Page (package); data from PubChem, NCBI · Unlicense
Web platform APIs used: Canvas 2D, WebGL, File API, Clipboard API.
- OpenChemLib resources (COD torsion library, MMFF94 tables) by Idorsia Pharmaceuticals / cheminfo (data from the Crystallography Open Database) (BSD-3-Clause (OpenChemLib); COD data CC0) — 3D conformer generation and force-field optimization, served from /vendor/openchemlib/resources.json
- PubChem Periodic Table by National Center for Biotechnology Information (NCBI) (Public domain (US government work)) — standard atomic weights for the molecular weight calculator
Full license texts: third-party notices · all credits
Frequently asked questions
Can I open protein structures?
Yes. Open a PDB or mmCIF file in the 3D viewer: proteins are drawn as a cartoon with ligands as sticks. Water molecules are hidden in cartoon mode.
How do I calculate a molecular weight from a formula?
Open the Molecular weight tab and type the formula, for example C6H12O6, Ca(OH)2 or CuSO4·5H2O. You get the mass in g/mol and the percentage of each element.
Which names can I type?
About a hundred common molecules: simple compounds, solvents, sugars, amino acids, nucleobases, vitamins and well-known drugs. For anything else, enter a SMILES string or draw the structure.