What is GSM? A Complete Guide to Paper and Card Weight
If you've ever bought cardstock and wondered what "250gsm" actually means — or why one 300gsm card feels sturdier than another — this guide is for you. After 20 years supplying card to crafters and stationers, Syntego has distilled everything you need to pick the right weight first time, whatever you're making.
Quick answer: GSM (grams per square metre) is the standard measure of paper and card weight. Higher GSM means heavier, stiffer, sturdier material; lower GSM means lighter and more flexible. For most greeting cards and invitations, 250gsm is the reliable all-rounder. For premium, standalone luxury cards, choose 300gsm. For liners, layering and inserts, use 120–170gsm paper.
What Does GSM Mean?
GSM stands for grams per square metre — the weight of a single sheet of paper or card measured at one square metre in size. It is the industry-standard unit for describing how heavy, and generally how thick and sturdy, a paper or card is.
- Higher GSM = a heavier, stiffer sheet
- Lower GSM = a lighter, more flexible sheet
As a rough rule of thumb: anything under about 150gsm is usually called paper, and anything above is called card — though the line is blurry, since finish and fibre content affect how thick a given weight feels in the hand.
Important caveat: GSM measures weight, not thickness directly. A textured or bulky card can feel thicker than a smooth card of the same GSM, because the surface adds loft. That's why a 250gsm linen card and a 250gsm smooth card can feel quite different to hold.
GSM Guide by Use: Which Weight Should You Choose?
| GSM Range | Category | Best Used For |
|---|---|---|
| 80–120gsm | Everyday paper | Printer paper, lightweight craft paper, inserts, liners, layering, origami. Too flimsy for a standalone card. |
| 120–170gsm | Light card | Invitation liners, layered elements, backing sheets. |
| 200–250gsm | Card-making sweet spot | Greeting cards and invitations that stand on their own while still folding cleanly. Syntego's Silkweave linen card is 250gsm for exactly this reason. |
| 250–300gsm | Premium card | Luxury invitations and keepsake cards. Syntego's pearlescent card is 300gsm. |
| 300gsm+ | Heavyweight card | Standalone signage, box-making, structural craft. Can be harder to fold cleanly without scoring. |
How Finish Changes the Feel
Weight isn't the whole story. A linen or textured finish adds surface depth and a tactile, premium quality that a smooth card of the same GSM won't have. A pearlescent coating adds shimmer and a little extra rigidity. When choosing card, consider both:
- Weight (GSM) — for sturdiness and stiffness
- Finish — for look, texture and feel
Our Simple Recommendation
- 135gsm Silkweave linen paper — a heavyweight, durable paper with a beautiful linen texture. Ideal for liners, layering, and premium stationery inserts.
- 250–300gsm — step up for extra luxury or a card that stands alone without support.
- 120–150gsm papers — drop down for anything you're layering or using as a liner.
Frequently Asked Questions
Is higher GSM always better?
No. It depends on the job. 250gsm is ideal for most cards and invitations, since very high GSM can be hard to fold and is overkill for layered or lightweight elements.
What is the difference between paper and card?
Paper and card are distinguished mainly by weight: material under about 150gsm is usually called paper, and material above 150gsm is usually called card. Finish and fibre content can blur this line.
Does GSM measure thickness?
No. GSM measures weight per square metre, not thickness. Textured or bulky sheets can feel thicker than smooth sheets of the same GSM because of surface loft.
What GSM is best for wedding invitations?
250–300gsm is typically best for wedding invitations, giving a substantial, quality feel appropriate for a keepsake item.
What GSM is standard printer paper?
Standard office printer paper is usually around 80–100gsm, which falls into the lightweight paper category rather than card.
What GSM is a business card?
Business cards are typically 300–400gsm, which sits at the heavyweight end of the card range for durability and a premium handfeel.
Explore Syntego's Card Range
Ready to choose your card? Explore our White Silkweave linen card and Ivory Silkweave linen card, or browse the full A4 card range.
