Paper Weight & GSM Calculator
Convert between pounds and grams per square metre for bond, text, cover, and index paper stocks, and get a recommended gsm range for the medium you're drawing with.
Converted weight
Recommended paper weight
Smooth or lightly toothed cartridge paper — heavy enough to erase and layer graphite without pilling.
Why lb and gsm don't line up 1:1
Grams per square metre is a true area-based measurement, so 200gsm always means the same physical weight of paper. The US "lb" system instead measures 500 sheets of a category's historical parent sheet size before it's cut down — so the conversion factor from lb to gsm depends on which basis (bond, text, cover, or index) the number belongs to. This tool uses the standard published basis-weight conversion factors for each category to convert either direction.
When in doubt, gsm is the more reliable spec to shop by, since it doesn't depend on knowing which basis a supplier is quoting.
Frequently Asked Questions
Why does 24lb paper convert to a different gsm than 24lb cover stock?
A US "lb" weight is a basis weight: the weight of 500 sheets at that paper category's standard, uncut parent sheet size. Bond/writing paper is measured on a 17×22in parent sheet, text/book paper on 25×38in, cover on 20×26in, and index on 25.5×30.5in. Because the parent sheets differ, the same lb number means a physically different sheet weight across categories — gsm (grams per square metre) is the fairer, size-independent comparison.
What gsm is a typical sketchbook?
Most everyday cartridge sketchbooks run 90–160gsm — light enough to fill quickly but heavy enough to erase and layer graphite without pilling or tearing. Mixed-media and watercolor-pencil pads jump much higher, commonly 300gsm and up, because wet techniques need a heavier, sized sheet to resist buckling.
Do I need heavier paper for ink than for pencil?
Usually yes, if any wash or wet blending is involved. Dry graphite and dry colored pencil work fine on a lighter 90–160gsm sheet. A fineliner with even a light water wash benefits from 160–224gsm smooth or hot-press stock so the ink doesn't feather or the sheet doesn't cockle.
What's the difference between cold-press and hot-press for watercolor pencil?
That's texture, not weight, but the two often go together: cold-press sheets have a pronounced tooth that grips pigment and blends well with a wet brush, while hot-press is smoother and better suited to fine detail. Either way, look for 300gsm (140lb) or heavier if you plan to wet-blend, so the sheet doesn't warp.
Educational tool only. Basis-weight conversion factors are industry-standard approximations; always check a specific paper's printed gsm or lb rating against the manufacturer's own spec sheet before buying in bulk.