Paper weight usually refers to the thickness, sturdiness, and feel of a sheet of paper. It’s measured differently depending on the region: 

• GSM (grams per square metre) – Used in the UK and internationally. It measures the weight of a single sheet sized 1m². The higher the GSM, the thicker and heavier the paper. 
• lb (pound) basis weight – Common in the US. It measures the weight of 500 sheets (a ream) of a standard size for that paper type.

Here’s a quick guide to common GSM paper weights and their uses:

👉 A useful rule:

• Under 100 GSM = lightweight, bendable.
• 100–170 GSM = medium, good for brochures/flyers.
• 170–250 GSM = heavy, durable.
• 250+ GSM = card stock and board.