Paper Weight for Journals: What GSM Actually Buys

2026-09-16 · Yesterself

GSM is the one number a notebook maker will nearly always print on the band around the cover. It is a real measurement, honestly taken. It just does not answer the question people are actually asking when they look at it, which is: will my pen behave on this?

What gsm actually measures

Grams per square meter. Cut one square meter of the sheet, weigh it, read the grams. That is the whole definition. It is a mass, not a thickness, not a hardness, and not a promise about ink.

Two consequences follow, and both break the assumptions people bring to the shelf.

Weight is not thickness. Papers differ in bulk, which is how much volume a given mass occupies. A soft, lightly pressed 80gsm sheet can be physically thicker than a dense, heavily rolled 100gsm one. If a notebook advertised at a higher weight ever felt thin in your hand, this is usually why.

Weight is not opacity. How much of yesterday's page you see through today's is partly mass and partly fillers. Minerals such as calcium carbonate and titanium dioxide scatter light, and a well-filled 70gsm can hide more than a plain 80.

For a reference point you already own: office copy paper is usually 75 or 80gsm. That is the middle of the journal range, not the bottom of it.

The two properties that do the rest of the work

Two sheets can weigh the same and behave nothing alike. This is why.

Sizing is the treatment that makes paper resist liquid instead of drinking it. Some is mixed into the pulp, some applied to the surface afterward. Unsized paper is blotting paper: ink spreads along the fibers, lines grow fuzzy edges, and dots where you paused turn into stars. That spreading is called feathering, and it is a sizing problem, not a weight problem.

Coating is a mineral layer spread over the base sheet. It holds ink on top instead of letting it sink in, which buys crisp lines and no feathering, and costs you long drying times and smearing. Most notebook paper is uncoated. Glossier stock is not, and it is the usual culprit when a heavy, expensive page refuses to dry.

Smoothness is the third. A calendered, glassy sheet feels wonderful under a nib and keeps ink on the surface longer, so it dries slower than a toothier page of the same weight.

Three pens, four weights

Use the same kit each time, because one pen only tells you about one ink.

• A ballpoint. Oil-based paste, laid down thinly, dries almost on contact. The least demanding thing you can put on paper.
• A 0.5mm gel pen. Water-based, and far wetter than it looks.
• A fountain pen, medium steel nib, ordinary blue-black ink. The wettest, slowest and most honest of the three.

Write the same thing with each: a few lines of normal handwriting, a hard-pressed signature, and a patch of cross-hatching where the ink pools. Wait a minute, drag a finger across it, turn the page.

70gsm and under

The ballpoint is fine. What you notice instead is embossing, ridges pushed into the back of the sheet by your signature. The gel pen shows through as a gray shadow and can bleed at the dots where you stopped moving.

The fountain pen is where the sheet declares itself, and where the number tells you least. A cheap 70 feathers and bleeds within a word. A well-sized 70 can be close to flawless. Tomoe River, the paper fountain pen users hoard, has long been made at around 52gsm and takes wet ink better than most sheets twice its weight. The most famous paper in that hobby is thinner than the copy paper in your printer.

80gsm

Copy-paper weight, and the default in most mass-market notebooks.

The ballpoint is crisp. The gel pen is comfortable, with mild show-through. The fountain pen is a coin flip decided by what the sheet was finished for. Office 80 is prepared for toner, so a wet medium nib often feathers on it. An 80 sized for pens holds that same nib cleanly. Same number, opposite result.

100gsm

The weight most often labeled fountain pen friendly, and where a wet nib usually stops reaching the other side.

The ballpoint gains a stiffer page and less embossing, nothing more. The gel pen's show-through mostly disappears. The fountain pen line holds its edges, and drying time gets longer, because a smoother, better-sized sheet keeps ink on the surface where a hand can smear it. That trade is worth knowing about before you pay for it.

120gsm and up

Cardstock territory once it is bound into a book.

The ballpoint and the gel pen have nothing left to gain. The fountain pen goes one of two ways. Some 120gsm sheets are the best surfaces you will ever write on. Others are coated or finished for laser printing, and there the ink pools, dries slowly and smears, because coating was doing the work the weight got credit for.

Past 100gsm you are usually buying opacity you already had. What you pay for it is the part nobody prints on the band.

Paper decides whether writing survives contact with a pen. When writing lives on a phone instead, the question becomes whether it survives contact with a company. Yesterself is built so the archive is never hostage: export is free forever, in open formats, and there is no account, email or password, only twelve words you hold. It is not released yet, so there is a waiting list and nothing else.

The hidden trade

A notebook has a fixed spine. The maker chooses a block thickness that fits the cover and the binding, and paper weight then eats into the page count.

Roughly, if bulk is similar, sheets that are 25 percent heavier are about 25 percent thicker. Take a 192-page notebook at 80gsm and rebuild it at 100 without changing the thickness of the block: you land near 150 pages. Same book in the hand, a fifth less writing in it.

The maker has three levers and will pull at least one. Raise the price. Cut the page count. Or hold both and buy a cheaper sheet at the higher weight, which is how you end up with a 100gsm page that feathers.

There is a physical cost too, and it is easy to compute. An A5 leaf is about 0.031 square meters. A 240-page book is 120 leaves, so the paper alone weighs about 300 grams at 80gsm and about 370 at 100. Seventy grams is not much until it is in a bag every day alongside everything else.

None of that argues for thin paper. It argues that "heavier is better" is an incomplete sentence. Heavier is more opaque, more expensive, more forgiving of wet ink, and shorter.

How to choose without buying four notebooks

1. Test with the pen you actually use. Not the nicest pen you own. The one that will be in your hand at eleven at night.
2. Ask what the sheet was made for, not just what it weighs. A maker who knows the answer will tell you it is sized for fountain pens, or that it is not. Silence usually means office stock.
3. Buy one sheet or one small pad before a whole book, especially above 100gsm, where drying time becomes the thing that annoys you.
4. Decide whether you write on both sides. If you do not, show-through stops mattering and you can drop a weight class and gain pages.
5. Weigh pages against thickness deliberately. A year of most people's writing is more pages than they expect. Running out in October is a worse outcome than a faint shadow of yesterday.
6. Compare leaf counts, not only weights. Two books at the same price and the same thickness, one at 80gsm and one at 100, are not the same purchase. Ask how many pages each one holds before you decide which you are buying.

The number on the band is a starting filter, not an answer. Between 80 and 100gsm, sized for pens, is where most journal paper worth owning lives, and inside that band the finish decides everything the number gets credit for.

Common questions

What gsm paper is best for journaling?

For most people, somewhere between 80 and 100gsm. Below 80 is fine if the paper is well made, and above 100 mostly buys you thickness you were not short of.

Does higher gsm stop bleed-through?

It reduces it without settling it. Bleed-through depends mostly on how absorbent the surface is, and a well-sized 80 can hold a wet nib better than a poorly sized 120.

Is 80gsm copy paper the same as 80gsm notebook paper?

They have the same mass per square meter and can behave completely differently. Copy paper is finished for toner or inkjet, while paper meant for pens is usually sized and smoothed with liquid ink in mind.

Why does my 100gsm notebook feel thinner than an 80gsm one?

Weight and thickness are separate properties. A compressed, heavily rolled sheet takes up less space than an airy one of the same mass, so bulk can reverse what the number suggests.

Does heavier paper mean fewer pages?

Usually, for the same spine thickness and price. Moving from 80 to 100gsm at the same block thickness costs roughly a fifth of the leaves unless the maker charges more.