PDF templates that fill an e-ink screen exactly (reMarkable, Supernote, Kindle Scribe)

If you open a normal US Letter or A4 PDF on a reMarkable or a Supernote, it almost fits. The
screen's aspect ratio is 3:4, Letter is 8.5:11 and A4 is 1:√2, so the device scales the page down
and leaves a strip at the bottom or side. A 5 mm dot grid on Letter comes out at about 3.7 mm on
a reMarkable 2, and the strip is wasted space you can't write on.

The fix is to stop thinking in paper sizes and size the PDF page from the screen itself. I did
this for the e-ink templates in a graph paper generator. Here are the formula, the numbers and a
few things that only showed up on the actual devices.

Page size = pixels ÷ ppi

A PDF page is measured in points, 72 per inch. An e-ink screen has a resolution in pixels and a
density in pixels per inch. Divide one by the other and you get the screen's physical size, which
is the page size you want:

const PT_PER_IN = 72;
const pagePt = (px, ppi) => (px / ppi) * PT_PER_IN;

// reMarkable 2: 1404 × 1872 px at 226 ppi
pagePt(1404, 226); // 447.29 pt  (6.21 in)
pagePt(1872, 226); // 596.39 pt  (8.28 in)

A PDF with a 447.29 × 596.39 pt MediaBox fills the reMarkable 2 screen edge to edge, with no
scaling. A 5 mm grid is then 5 mm on the glass, the same as on paper.

Here are the values I use:

Device	Pixels	ppi	Page (pt)
reMarkable 2 (also Supernote A5 X, Boox 10.3″)	1404 × 1872	226	447.29 × 596.39
reMarkable Paper Pro	1620 × 2160	229	509.34 × 679.13
Supernote Manta (A5 X2)	1920 × 2560	300	460.8 × 614.4
Supernote Nomad (A6 X2)	1404 × 1872	300	336.96 × 449.28
Kindle Scribe	1860 × 2480	300	446.4 × 595.2

Two devices share a resolution here (reMarkable 2 and Nomad: both 1404 × 1872) but have very
different screen sizes. Pixel count alone isn't enough. You need the ppi, or a 5 mm grid becomes
3.8 mm on the Nomad.

Export PNGs at native pixels too

Some apps (and some people) prefer image templates. The reMarkable's own template folder, for
example, uses PNGs at the screen resolution. If the drawing is already in points, a PNG at native
resolution is just a scale factor:

const scale = px / pagePt;           // = ppi / 72, e.g. 226 / 72 ≈ 3.139
canvas.width = 1404; canvas.height = 1872;
ctx.scale(scale, scale);
drawPage(ctx);                       // same geometry as the PDF

Rendering at exactly the screen size means no resampling on the device, so 1 px lines stay sharp
instead of turning into 2 px grey smudges.

What changes on e-ink

A few things that work on paper didn't work on the screens:

• Colour. Light blue (#8eb1d6) looks nice on paper and becomes a weak light grey on a monochrome panel. A mid grey (#555555 or so) gives about the same contrast as blue ink on white paper. On the colour Paper Pro, blue is fine again.
• Line weight. 0.35 pt lines are 1 px or less at 226 ppi and partly disappear depending on where they fall on the pixel grid. 0.5 pt is the minimum that survives everywhere; dots need to be a bit bigger than on paper (about 2 pt diameter).
• Margins. You don't need a printer margin, but the reMarkable's toolbar covers the left edge when it's open, and the Supernote has a status bar. A 3–4 mm margin keeps the grid from running under them. And keep fitting whole cells inside the margin and centring them. A cut-off square at the edge is just as ugly on glass as on paper.
• No header. A "Name / Date" line is useful on school paper and wasted space on a notebook template, where the device stores the date anyway.
• Multi-page files. For a notebook it's handy to export one PDF with 50 or 100 identical pages. If every page shares a single content stream (one /Contents object referenced by all pages), a 100-page template is barely bigger than a 1-page one.

Getting the template onto the device

• reMarkable: import the PDF through the desktop or mobile app and write on it as a notebook. Custom PNG templates need SSH access and editing templates.json, so the PDF route is easier for most people.
• Supernote: copy the PDF (or a PNG) into the MyStyle folder for templates, or into Document to annotate it.
• Kindle Scribe: send the PDF with Send to Kindle and choose to keep it as a PDF (not converted), so you can write on it.

The same idea works for any screen: get the pixels and the ppi from the spec sheet and size the
page from those, not from a paper format. If you'd rather not compute it, the generator at
graphpaperpdf.net has these devices in the page-size
menu for grid, dot, lined and isometric templates.