Weight matters less than you think—but 100gsm is the sweet spot.

Most planners with 100gsm paper will handle everyday pens fine, no ghosting or bleed. If you’re a fountain pen user or like heavy markers, jump to 120gsm or look for special coatings.

The number people quote is “gsm” (grams per square meter). Paper gets thicker and less transparent as that number goes up. A 70–80gsm planner is thin—you’ll see the previous page through it, and bold inks will se Through. 90gsm is borderline fine for ballpoints but risky. 100gsm is where normal note-taking stops being a gamble. 120gsm and up feels almost cardstock-like and will tank most anything you throw at it.

But here’s the catch: gsm isn’t the whole story. Two 100gsm papers can behave completely differently. Some papers are coated or “sized” to stop ink from soaking in (that’s what bullet journal brands like Scribbles That Matter or Archer & Olive sell you on). Others are just thick but porous, so bleed still happens with wet inks. The real test is pen + paper combo, not the weight alone.

So don’t obsess.