GSM — grams per square meter — is the single most important number on a paper bag specification. It determines how much the bag can carry, how it feels in a customer's hand, and what you pay per unit. Specify too low and bags fail in use; specify too high and you're shipping (and paying for) paper weight your application doesn't need.
What GSM actually measures
GSM is the weight of one square meter of the paper the bag is made from. A bag made from 100 GSM kraft uses paper weighing 100 grams per square meter. It is a measure of paper density, not bag weight — a large 90 GSM bag can weigh more than a small 120 GSM one. Higher GSM generally means higher tensile and burst strength, a stiffer structure, and a more premium feel.
The practical GSM ranges
| GSM range | Character | Typical applications |
|---|---|---|
| 60–80 GSM | Light, economical, flexible | SOS grocery bags, pharmacy bags, bakery pouches, light takeaway |
| 80–100 GSM | The general-purpose sweet spot | Standard retail carry bags, food delivery, mid-weight groceries |
| 100–120 GSM | Sturdy, holds shape, prints richly | Fashion retail, multi-bottle carriers, heavier food orders, mailers |
| 120–150 GSM | Premium stiffness and drape | Boutique and luxury retail, gifting, wine carriers, corporate events |
Five factors that should drive your choice
1. Load weight and shape
A bag carrying 2–3 kg of groceries needs materially less paper than one carrying two wine bottles (heavy, concentrated load) or a folded winter coat (light but bulky). Think about your worst realistic load, not the average one — customers remember the bag that failed.
2. Handle type
Handles concentrate stress. Twisted-handle bags are usually specified at 100 GSM and above because the handle patch pulls on the paper; SOS bags with no handles are gripped by the body and work fine at 60–90 GSM. There's more on this trade-off in our handle types guide.
3. Single vs double ply
Instead of jumping to a very heavy single sheet, some applications use two lighter plies. Double-ply construction adds tear resistance and moisture tolerance — common for heavier grocery and food-service bags. It's often more economical than an equivalent single heavy sheet.
4. Print and brand impression
Heavier paper prints with less show-through, holds crisp edges, and simply feels more expensive. If the bag is part of your brand experience — boutiques, gifting, premium F&B — the step from 90 to 110+ GSM is usually worth more than any print upgrade.
5. Cost and freight
Paper is priced by weight, so GSM moves your unit cost almost linearly — and for importers it also moves shipment weight. Across hundreds of thousands of bags a year, trimming 20 unnecessary GSM is real money; cutting 20 necessary GSM is a customer-complaint program.
Brown kraft vs white kraft at the same GSM
At equal GSM, unbleached brown kraft is marginally stronger (bleaching slightly shortens fibres), visually "eco", and cheaper. White (bleached) kraft gives cleaner color reproduction for printed brand artwork and a more polished look for fashion, cosmetics, and pharmacy applications. Neither is wrong — it's a brand decision more than an engineering one.
How to decide, in practice
- List your heaviest realistic contents and weigh them.
- Pick the format and handle first (that constrains sensible GSM).
- Start from the table above, then order samples at two adjacent GSMs — e.g. 90 and 110 — and load-test both with your actual products.
- Choose the lighter one that passes with margin.
Not sure where to start? Tell us what goes in the bag — we spec GSM, ply, and format against your actual use case every day. Request a quote and include your product and load details, or browse our product range with GSM ranges listed per format.