PDF Export

To export a PDF, choose File > Export PDF..., pick the page size and margins, check the preview, and click Export PDF. The PDF libraries load the first time you export, so the button reads Generating... until the download starts. There is no keyboard shortcut for PDF export.

The drawing is written as vector graphics, so bonds and labels stay sharp at any print size. It prints at true size: one canvas pixel is 0.75 pt, 96 pixels to the inch, the same size an SVG or PNG export has when you place it in Word.

Print a mechanism on A4

Choose File > Export PDF....
Set Page Size to A4 and Orientation to Landscape for a wide reaction scheme.
Leave Margins on Normal, and leave Auto-fit content to printable area and Center on page checked.
Check the preview: the drawing sits on the sheet where and at the size it will print, and the dashed box is the printable area inside the margins.
Click Export PDF.

Options

Option	What it does
`Filename`	The downloaded file’s name; `.pdf` is added. Pre-filled as in SVG export.
`Scope`	`All Content` or `Selection Only`. `Selection Only` exports just the selection on one sheet, also in a paged or slide document.
`Page Size`	Letter, A4, A3, Legal, Tabloid, B5, Executive, Widescreen or Standard; each entry shows its dimensions. When the document has a custom size in Page Setup, the list also offers `Custom` with that size.
`Orientation`	`Portrait` or `Landscape`. Widescreen and Standard are already wider than tall and always print landscape.
`Margins`	A preset (Normal, 1 in all round; Narrow, 0.5 in; Wide, 1 in top and bottom and 1.5 in left and right; None) or `Custom`, which unlocks the `Top`, `Right`, `Bottom` and `Left` fields. Values are in inches.
`Auto-fit content to printable area`	Shrinks the drawing to fit inside the margins. It never enlarges a small drawing. On by default.
`Center on page`	Centers the drawing in the printable area; cleared, the drawing sits at the top-left margin. On by default.
`Include background`	Fills the whole sheet with the chosen color. On by default, white.

Preview

The preview shows the sheet with your drawing on it, placed by the same layout the export uses (paper, margins, fit and centering), next to the paper name, orientation and dimensions and the size of the printable area. For a document with several pages or slides it shows the first one and reads Page 1 of N or Slide 1 of N. It updates when you change a layout option.

The preview also warns you before you export:

Larger than the printable area: edges will be cut off (turn on Auto-fit) appears when Auto-fit is off and the drawing does not fit inside the margins.
In a paged or slide document, a count of items that sit on no page appears. Those items are left out of the PDF.
Nothing to export appears when there is nothing in scope.

The same two warnings (cut-off edges and items on no page) appear again as messages after the export.

Starting values

The dialog starts from your last PDF export, in any document and after a reload. The filename is not carried between documents. If you have never exported a PDF, the options start at Letter, Portrait, Normal margins.

When the document uses Page Setup pages, Page Size and Orientation always start from Page Setup, even if you have exported PDFs before. Exporting a paged document does not change the paper size remembered for infinite-canvas documents. Margins and the other options still start from your last export (or from Page Setup if you have never exported a PDF).

Multi-page documents

When Page Setup divides the document into pages or slides and Scope is All Content, the PDF gets one sheet per page or slide, in order.

Each page or slide is drawn full-bleed: it fills its sheet with no margin inset, because the document’s own layout already placed the content on it. If the paper shape differs from the page shape, the page is scaled to fit and centered, with blank space on two sides. Nothing is stretched. This works the same in Paged Document and Slide Deck mode.

Because the pages print as laid out, the dialog greys out the margin preset and fields, Auto-fit content to printable area and Center on page, and shows the note Set by Page Setup: each page or slide prints as laid out. Include background still applies and fills every sheet.

An item whose anchor point sits outside every page is not in the PDF; the preview and a message after export give the count. Move it onto a page to include it.

With Selection Only, a paged or slide document exports the selection on one sheet, the same way as an infinite canvas, and margins, Auto-fit and Center apply again. On an infinite canvas the PDF always has one page holding the whole drawing or the selection.

What the PDF contains

Some content is adjusted on the way into the PDF so it prints as it looks on the canvas:

Fonts. Arial, Helvetica, Times New Roman, Georgia and Courier New text is set in the PDF standard fonts Helvetica, Times and Courier, which every PDF reader has. A Google font or an uploaded TTF or OTF font is embedded as a font file. See Font Embedding & Convert to Paths.
Greek letters and symbols. Text with characters the standard fonts lack, such as Greek letters, the minus sign, arrows (including the equilibrium arrow) and superscript signs, is set in the bundled Liberation font of the same style, or in DejaVu Sans for what Liberation lacks, sized to keep its width on the canvas. A Google or uploaded font that cannot draw a character falls back the same way instead of printing it blank.
Rich text. Text boxes and arrow labels are placed as the browser lays them out: the same wrap points, spacing, blank lines, justified text, subscripts and superscripts, nested bullets, underline, strikethrough and highlight.
Colours. Charges, atom numbers and R/S and E/Z labels keep their own colours, and a bond between differently coloured atoms keeps both colours, including hashed, wedge, wavy and dashed bonds.
Gradients. Gradient fills keep their direction and shape, so 3D captures keep their sphere shading. A gradient stroke is drawn as bands of its colours.
Orbital pictures. A bond behind a ribbon in front is hidden, as on the canvas.
Pattern fills stay vector geometry.
Filter effects such as drop shadows, glow and blur become images inside the PDF. A progress message appears while this runs.
Invisible zero-width characters left by text editing are removed, so text does not print with gaps between letters or inside subscripts.
Imported SVG charts often fix each label’s width for the chart’s own font. The export drops that fixed width and lets each label lay out in the PDF’s font; without this, Acrobat and Chrome could drop most of the content on that page.

If the app is displayed in a dark theme, a PDF on a light or transparent background is still drawn with dark ink, so bonds do not come out near-white on the white page. A dark background keeps the light ink. See Light and dark.

The PDF is compressed, and its document properties carry the title, author and description from the document’s metadata, with Molkit as the creator.

If a drawing relies on filters, compare the PDF with the canvas. If the export fails, an error message gives the reason.