MolDraw › Chemistry tools › SMILES to Image Converter
SMILES to Image Converter (PNG and SVG)
In short: Paste one or more SMILES and download clean 2D structure images as SVG or PNG, one per molecule or as a labelled grid. It is free, works in your web browser and needs no download.
Black bonds, element-coloured heteroatoms and a fixed bond length give figures that look the same across a paper or slide deck. Set the line width, background and PNG scale, and add atom numbers when you need them.
Ready.
How the image is made
Your SMILES is read and given 2D coordinates by OpenChemLib, the same open-source engine MolDraw's other structure tools use. The structure is then drawn by MolDraw's own renderer: skeletal formula, carbon atoms as line ends, heteroatoms as element symbols with their hydrogens (OH, NH₂), charges, wedge and hash bonds for stereocentres written with @ or @@, and E/Z double bonds drawn as written.
The bond length is fixed in pixels, so every molecule you export at the same setting has the same scale. That is what journals ask for in a figure with several structures. The image is cropped close to the molecule.
| Option | What it does | Typical choice |
|---|---|---|
| Bond length | Length of one bond in the SVG (and in the PNG at 1×) | 30–40 px for slides; ACS style is 14.4 pt |
| Line width | Multiplies the bond line thickness | Normal; Bold for posters |
| Colours | Element colours (O red, N blue, S yellow, F and Cl green, Br brown) or all black | All black for most journals |
| Background | Transparent lets the slide or page colour show through | White for Word documents |
| Aromatic rings | Alternating double bonds (Kekulé) or a circle in the ring | Kekulé |
| PNG scale | 1× is the SVG size; 4× gives four times as many pixels per side | 3× or 4× for print |
How to convert SMILES to PNG or SVG
- Paste one SMILES per line. Add a name after a space if you want it as the label, e.g.
CCO ethanol. You can also open a .smi or .txt file. - Pick the bond length, line width, colours, background and aromatic style. Tick Atom numbers for NMR or reaction figures.
- Press Draw structures. Lines with errors are listed with the reason and the character position.
- Press Download SVG or Download PNG. With several SMILES you also get one grid image, and each structure has its own SVG and PNG buttons.
Limitations
- The 2D layout is automatic. Large rings, macrocycles and crowded cages can come out with overlapping atoms. Open the structure in the MolDraw editor to adjust it by hand.
- Stereo is drawn only if the SMILES contains it (@, @@, / and \). The tool does not guess configurations.
- Explicit hydrogens on carbon are not drawn; atom numbers skip implicit hydrogens.
- Text in the SVG uses the font Times New Roman. If a computer does not have it, a similar serif font is used. Convert text to outlines in a vector editor if a journal needs that.
- Up to 200 SMILES at a time. Everything runs on your device; very large molecules (several hundred atoms) can take a few seconds.
Need to edit the drawing? MolDraw is a free online chemical structure editor. Paste the SMILES there to move atoms, add arrows and export.
Open MolDraw editorFrequently asked questions
How do I convert a SMILES string to an image?
Paste the SMILES, press Draw structures, then Download PNG or Download SVG. The 2D layout and drawing run in your browser, so nothing is uploaded.
Should I use PNG or SVG?
Use SVG for papers, posters and slides: it is a vector file, stays sharp at any size and can be edited in Inkscape or Illustrator. Use PNG for web pages, chat and documents that do not accept SVG. Pick 3× or 4× scale for print.
Can I make one image of many molecules?
Yes. Paste up to 200 SMILES, one per line, with an optional name after each. The tool draws a grid with the number of columns you choose, the same bond length in every cell and the names as labels.
What do the atom numbers mean?
They follow the order of the atoms in your SMILES, starting at 1. Implicit hydrogens are not numbered. This is handy for NMR assignments and for matching atoms between programs.
Why is the layout different from PubChem or ChemDraw?
Each program has its own 2D layout method. This tool uses OpenChemLib for coordinates. For a hand-tuned figure, open the structure in the MolDraw editor and move atoms before exporting.
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