Wedding Invitation GSM and What Weight to Choose

Three hundred gsm is the usual weight for a wedding invitation card, and if you want one answer, that is it. It is the most common weight on our shelf too: 49 of the 99 papers we print on are 300 gsm card. Everything we print as a card sits between 270 and 372 gsm, and the lighter weights you will see in paper catalogues are what envelopes are made from.

What gsm actually measures

GSM is grams per square metre, the weight of one square metre of that paper. It measures weight, not thickness, which is why two cards at the same gsm can feel quite different in the hand. A soft cotton stock and a smooth matt stock, both at 300 gsm, weigh exactly the same and behave differently under a pen.

Because it is a weight per area, you can work out what a card weighs before you order anything. An A6 card is 105 by 148 millimetres, so a 300 gsm A6 card comes in under five grams. A hundred of them is less than half a kilogram of paper, which matters later when we get to the post office.

The weights we print on

Every card we print is card weight, and the weight comes with the paper: you choose the paper, and its weight follows.

Several of the heaviest weights are made by bonding two lighter sheets together, which is why they land on 302, 340 and 372 rather than on a round number. A bonded card feels substantial, and it takes a crease differently to a single sheet.

Why we do not print cards on light paper

Paper catalogues list many of the same papers at 100 to 186 gsm, and they make lovely letterhead. We do not print invitations, details cards or RSVP cards on them. Our printer does not offer flat cards at those weights, and a card that light folds over in the hand rather than holding its shape. Every card in your set, the RSVP card included, prints at card weight.

Here is a quick way to feel the difference without a sample in front of you. Hold a card at one corner at arm's length and watch how far it bends. A 300 gsm card holds itself almost flat. A 120 gsm sheet folds gently over. That is the whole distinction, and it is what a guest registers as they slide the invitation out of the envelope, long before anyone thinks about a number.

The envelope is the light piece

Envelopes are folded and glued rather than cut flat, so they are made from lighter paper than the card they carry: 100 to 130 gsm, and never heavier, because that is what a clean fold needs. They come in two sizes, 130 by 190 millimetres for the invitation set and C6 at 114 by 162 millimetres for an A6 save the date. Twenty-four of our card papers have an exact envelope twin, same paper line and same colour, so the envelope can be made of the same stock as the card inside it. The rest pair with the closest colour on the envelope shelf.

So a suite stays on one paper naturally. The invitation, the details card and the RSVP card can all be the same paper at the same weight, and the envelope is its lighter twin where one exists. When you choose a paper in the design studio, its weight comes with it.

Weight, thickness and what it costs to post

Weight is almost never what makes an invitation expensive to send. Australia Post prices a small letter at up to 130 by 240 millimetres, up to 5 millimetres thick and up to 250 grams. A 300 gsm invitation with two more cards and an envelope is nowhere near 250 grams. The 5 millimetres is the number that catches couples out.

Our invitation envelope is 130 by 190 millimetres, which sits exactly on that 130 millimetre limit across the short side. So the postage question is not really about gsm at all. Flat cards rarely reach 5 millimetres on their own. What usually does is something raised: a wax seal, a ribbon, a pocket or a brooch.

Assemble one complete invitation, envelope and all, and take it to a post office counter before you buy a hundred stamps. It takes five minutes and settles the question for the whole print run.

When heavier stops helping

340 and 372 gsm papers are lovely to hold, and they are not automatically the better choice. They are the textured, bonded papers, and on the most textured of them fine detail sits differently than it does on a smooth matt sheet. If your design has hairline rules or very small type, the smoother papers at 300 gsm hold it more reliably.

There is a quieter constraint worth knowing before you fall for a design, too. None of the papers in the range are set up for large flooded areas of solid ink, so a deep colour comes from choosing a deep-coloured paper rather than from printing one. That decision is much easier to make at the start than halfway through.

Stationery is one of the smaller lines in an Australian wedding budget, well below the venue, catering and photography in the 2026 cost breakdown, so the gap between one paper and a heavier one is rarely the place to save money. Choose the paper you want to touch, and check the envelope at the counter. If you are still choosing sizes, our guide to invitation sizes and papers covers the three cards in the set.

Start your invitations

Sizes and papers from the Managing Matrimony print catalogue, September 2026; the range changes as mills do. Letter limits from Australia Post.