GSM (Grams per Square Metre) is the industry standard measurement for weight (thickness) of paper stock. It allows buyers and suppliers to guage the quality of paper when ordering. In general stock with a higher GSM number will offer improved weight and feel but certain media is suited to a specific GSM number. The list below provides an industry bench mark to the suggested GSM for popular printed material. In most instances the figures quoted represents the lowest GSM in which to achieve an acceptable standard of quality associated with the chosen material. Typically paper becomes card/board at weights above 300gsm and when larger surface areas can support themselves and appear more rigid. A business card at around 350-400gsm is a good example of the transistion point. If you have no benchmark or direct reference to the weight of the material you are producing request some printed samples from your chosen printer. This will help you to establish how variations in stock weight and finish can affect the feel and quality of your printed media. Though marginal additional print finishing such as lamination is a coating and can add to the final weight of the printed material.