Structural Formula Generator
Enter SMILES notation → display the 2D structural formula instantly, as a PNG with a free account. Ideal for chemistry, biochemistry, medicine and pharmacy. All calculations run locally in your browser, no data is sent.
The generator
Result
Valid
c1ccccc1
SMILES (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
PNG download with a free account. Your result comes along.
Examples and groups
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.
The guide Draw skeletal structures with ethanol explains why CCO describes ethanol while COC describes dimethyl ether. Five exercises with solutions connect the tool output to counting atoms and bonds.
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
Render
Enter or the Render button draws the picture. It follows the page colour scheme, light or dark, and the downloaded PNG gets the same background, 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; saving the flashcards comes with Essential.
Go further than the image
The tool stays free and needs no account; the PNG comes with a free account. From Essential your result stays too: it moves into a topic as study material, and Quanta schedules the reviews up to your exam.
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.