Somewhere around your third nice notebook, the number printed near the barcode starts to matter. 70gsm, 90gsm, 120gsm — these figures decide how a page behaves under your pen: whether ink comes through, whether the sheet feels flimsy or substantial, whether your favourite pen is a pleasure or a smear. Here is what each weight really changes, and how to choose one without buying five notebooks to find out.
What the Number on the Cover Actually Means
GSM stands for grams per square metre: the weight of one square metre of that paper. It measures mass, not thickness. Paper also has a caliper — its thickness in microns — and two sheets of the same gsm can differ there depending on how densely the fibres are packed and how hard the surface has been pressed smooth.
What gsm does tell you reliably is how much fibre sits between your nib and the other side of the page. That is the best single clue you have before you write on it. Three terms come up constantly, and they are not the same thing:
- Bleed — ink travels all the way through and shows on the reverse as a stain, or transfers onto the facing page. That side of the sheet is usually lost.
- Show-through (also called ghosting) — you see the shadow of your writing from the back because the paper is translucent. No ink has crossed; the sheet is simply thin. Pencil does this on cheap paper too.
- Feathering — ink spreads sideways along the fibres, leaving fuzzy edges instead of clean ones. This is about sizing and surface finish more than weight, though heavier sheets tend to be better sized.
A heavier paper is not automatically better behaved, but it is usually more forgiving: there is more material to absorb a wet line before it reaches the other side.
70gsm: Light, Cheap, and More Capable Than You Think
Seventy gsm is the paper of school exercise books and slim pocket notebooks. It is thin, inexpensive, and packs a lot of pages into a book that disappears into a coat pocket.
With a pencil or a ballpoint it is fine. Ballpoint ink sits on the surface rather than soaking in, so it rarely bleeds, and the show-through stays faint. A fine gel pen works too, though saturated gel inks leave a visible shadow on the reverse. Beyond that, things get harder: a fountain pen with a wet medium or broad nib will show through clearly and may bleed outright, and a highlighter goes straight through.
None of that makes 70gsm unusable — it makes it a paper you work with:
- Write on one side only when using a fountain pen or highlighter. A one-sided 70gsm notebook is still cheaper and lighter than a two-sided 120gsm one.
- Slide a sheet of card or blotting paper under the page you are writing on to catch ink before it reaches the next sheet.
- Keep it for drafting, lists and thinking on paper — writing you would not want to be precious about.
90gsm: The Comfortable Middle
Ninety gsm is where most good everyday journals sit, and for most journalers it is the right answer. The page has some body under the pen, the notebook still closes flat and fits in a bag, and you get a sensible number of pages for the thickness.
It handles the ordinary range of journaling tools well: fine and medium fountain pens with moderate inks, gel pens, fineliners, and most highlighters if you draw the stroke lightly and let it dry. You will see a faint shadow of your writing on the reverse, especially with dark ink, but it reads as background rather than interference. Bleed is uncommon unless the nib is very wet or the paper is a poor example of its weight.
That last point bears repeating. Ninety gsm from one mill can feel quite different from 90gsm at another, because sizing, surface finish and fibre blend vary. A well-made 80gsm sheet can outperform a loose 100gsm one. Weight is a guide, not a guarantee.
120gsm: Thick Paper and Its Honest Trade-offs
At 120gsm the page starts to feel like card. Writing on it is genuinely pleasant: a soft pencil leaves a clean line, a broad fountain pen nib glides, and the sheet stays put instead of sliding. Show-through almost disappears, and you can use both sides with a wet pen without thinking about it. It also takes tools thinner papers cannot: brush pens, lettering fineliners, light marker work, rubber stamps, even a light watercolour wash — though notebook paper is not watercolour paper, and a wet wash will still buckle it.
The trade-offs are real. A hundred and twenty pages of 120gsm is a thick, heavy book, and page counts shrink if you want to stay portable. Some thick notebooks resist lying flat because the spine has so much bulk to bend. Smooth, heavy sheets can also be slow to dry, so a wet line may smudge if you close the book too quickly. And if you write with a ballpoint, you are paying in weight and money for a benefit you will never notice.
Matching Paper Weight to Your Pen
A rough pairing guide, based on how much ink each tool lays down:
- Pencil, ballpoint: 70gsm is plenty.
- Fine gel pen, fineliner: 70–90gsm, expecting a little show-through at the lower end.
- Fountain pen, fine nib, moderate ink: 90gsm. Use one side only on 70gsm.
- Fountain pen, medium or broad nib, wet ink: 100–120gsm.
- Highlighter: 90gsm with a light hand; 120gsm if you highlight heavily.
- Marker, brush pen, stamping: 120gsm or heavier.
Ink matters as much as nib. Two pens with the same nib width can behave very differently if one ink is wet and free-flowing and the other restrained. If a notebook you love shows through more than you would like, changing ink is often easier than changing notebooks.
How to Test a Notebook Before You Commit to It
You do not need to fill a book to learn how it behaves. Do this the day you bring it home, on a page near the back:
- Write one line with your driest pen and one with your wettest, side by side. Swipe highlighter over part of each.
- Watch the wet line for
Photo: Poppy Thomas Hill / Pexels
