Structural Formula Generator
Enter SMILES notation → display the 2D structural formula instantly and download it as PNG. Ideal for chemistry, biochemistry, medicine and pharmacy. All calculations run locally in your browser, no data is sent.
Powered by smiles-drawer (MIT) · Supports: rings, stereochemistry, all IUPAC-compliant compounds
Press Enter or click → to render
Display
Examples
c1ccccc1SMILES (Simplified Molecular Input Line Entry Specification) is the IUPAC standard for encoding chemical structures as text. Benzene: c1ccccc1 · Ethane: CC · Double bond: C=C · Triple bond: C#N
Learn structural formulas as flashcards
Download the PNG → upload to Quanta → FSRS automatically learns when you need the compound. Biochemistry, organic chemistry, pharmacology, all visual with spaced repetition.
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SMILES notation, quick reference
Basic structure
Heteroatoms
Rings
Stereochemistry
What is the structural formula generator for?
Chemistry studies
Visualize structural formulas for problem sets, exam and test preparation in seconds.
Medical studies
Display biochemical compounds, amino acids and pharmaceutical agents for biochemistry and pharmacology.
Research
Fast 2D preview for SMILES from publications, PubChem, ChemDraw export.
Flashcards
Download a PNG and import it into Quanta flashcards for spaced repetition.
Presentations
High-resolution structural formulas for seminars, posters and scientific papers.
Privacy
Fully client-side, no server, no data sharing, no account needed.
Three lines that teach you the notation
Copy one line into the input field. Each shows a different rule of SMILES notation, and together they cover what most broken lines get wrong.
| Compound | SMILES | Formula | The rule behind it |
|---|---|---|---|
| Acetic acid | CC(=O)O | C₂H₄O₂ | The round brackets are a branch, not an arithmetic bracket. (=O) hangs a double bond off the carbon in front of it, and the O that follows stays the singly bonded OH group. |
| Benzene | c1ccccc1 | C₆H₆ | Lower-case letters stand for aromatic atoms, and the digit 1 opens and closes the ring. Write C1=CC=CC=C1 instead and you get the same compound with its double bonds spelled out. |
| Alanine | N[C@@H](C)C(=O)O | C₃H₇NO₂ | The square bracket carries the stereo information: [C@@H] fixes the order in which the neighbours sit around the centre. Without it the generator still draws the compound, just with no defined configuration. |
Three moves to the picture
- 1
Enter a line or search a compound
If you have the SMILES code, type it into the field. If you do not, search the compound by name; 66 compounds come with a checked line, sorted into 13 categories from alkanes to nucleobases.
- 2
Choose the rendering
Light or dark, both with element-specific colouring of the atoms. The choice carries over to the image you download, so the structural formula in your handout does not sit on a black background.
- 3
Download or keep learning
The PNG comes out with the SMILES code in its filename, so you can find it again later. Alternatively you turn the compound into two flashcards.
What is computed, and where
The drawing is done by smiles-drawer, an open-source library under the MIT licence. It parses the SMILES line, lays the atoms out in the plane and draws rings, aromatic systems and the wedge and hash bonds that carry stereochemistry.
SMILES stands for Simplified Molecular Input Line Entry Specification and goes back to Weininger in 1988 in the Journal of Chemical Information and Computer Sciences. The notation spread because it packs a whole structure into one line of text that you can copy, cite in a paper and pull out of PubChem.
The generator runs entirely in the browser. Your line is drawn on your own machine and is not sent to a server.
Where the generator stops
Four points you are better off knowing beforehand.
- The drawing is two-dimensional. If you want to see bond angles and spatial arrangement, use the 3D molecule builder, and that one needs a window of at least 1024 pixels.
- A line that smiles-drawer cannot parse produces an error message with the reason instead of half a picture. Unmatched brackets and ring numbers that are opened but never closed are the two most common cases.
- The generator cannot do reaction equations, mechanisms or arrows. It draws a structure, not a reaction.
- Flashcards are only built from a compound that exists in the stored data set. A line you typed yourself that the tool does not know has no checked name behind it, and a flashcard without a reliable back is a bad flashcard.
From the structural formula to a flashcard
From a recognised compound Quanta builds two flashcards: one shows the structure and asks for the name, the other shows the name and asks you to draw the structure. The back carries the formula and the category from the same data set the line itself comes from.
They are then studied with FSRS-6 (Ye et al. 2022, ACM SIGKDD). The generator itself needs no account for any of this; only saving the flashcards runs through signing up.
Frequently asked questions about the structural formula generator
How can I draw structural formulas online?
What is SMILES notation?
Is the structural formula generator free and usable without an account?
Which structures can I render?
Why is my SMILES line not being drawn?
The other two tools
Both also run in the browser and both also work without an account.
- 3D molecule builder
Place atoms, draw bonds, rotate in the 3D view. Needs a window of at least 1024 pixels.
- LaTeX formula editor
Render formulas live, with quick insert for physics, chemistry and maths.
- Formula sheet
The collection behind the editor, every formula with its source and a worked example.