Most wedding suites fail at the same two points: the folded piece is a hair too wide for the envelope, or the stack is too thick for a standard letter rate. Both problems are decided before a single ornament is drawn. This walkthrough covers the wedding invitation sizes that actually exist in the supply chain, the panel math behind a clean trifold, the card stock weights that fold without cracking, and the envelope and postage limits that quietly control the whole design.

The short answer on wedding invitation sizes

The standard wedding invitation size is 5″ x 7″ (127 x 178 mm), which slides into a standard A7 envelope. Everything else in the suite is sized down from there:

• Invitation: 5 x 7 in
• Details / reception card: 4 x 6 in or 3.5 x 5 in
• RSVP card: 4.25 x 5.5 in (A2) or 3.5 x 5 in (A1)
• RSVP envelope: A2 or A1, inserted unsealed inside the outer envelope

A trifold suite changes the math because the piece you design is flat and the piece you mail is folded. That difference is where most jobs go wrong. Unlocking the Secrets of Wedding Invitation Sizes covers this in more depth.

Standard invitation sizes and their matching envelopes

North American card and envelope chart

Card size (in)	Metric (mm)	Envelope	Envelope size (in)	Typical use
3.5 x 5	89 x 127	A1 / 4 Bar	3.625 x 5.125	RSVP, enclosure, smallest mailable card
4.25 x 5.5	108 x 140	A2	4.375 x 5.75	RSVP card and reply envelope
4 x 6	102 x 152	A6	4.75 x 6.5	Details card, save the date, postcard
4.25 x 6	108 x 152	A6	4.75 x 6.5	“Petite” invitation format
5 x 7	127 x 178	A7	5.25 x 7.25	Standard wedding invitation
5.25 x 5.25	133 x 133	5.5 square	5.5 x 5.5	Modern square, non-machinable surcharge
5.25 x 7.75	133 x 197	A8	5.5 x 8.125	Oversized upgrade
5.5 x 8.5	140 x 216	A9	5.75 x 8.75	Statement invitation, half letter
3.5 x 6.5	89 x 165	Pocket insert	n/a	Slim inserts for pocketfolds

Metric (A-series) sizes

Outside North America, suites are built on ISO paper. A5 is the closest thing to a “big” invitation and A6 is the everyday format.

Format	Size (mm)	Size (in)	Envelope
A5	148 x 210	5.83 x 8.27	C5 (162 x 229)
A6	105 x 148	4.13 x 5.83	C6 (114 x 162)
A7 (ISO)	74 x 105	2.91 x 4.13	C7
DL	99 x 210	3.9 x 8.27	DL (110 x 220)

Important trap: the North American “A7” envelope (5.25 x 7.25 in) and the ISO “A7” sheet (74 x 105 mm) share a name and nothing else. If a client in Europe asks for A7, confirm which one they mean before you order 500 envelopes.

The envelope fit rule: 1/4 inch, in both directions

An envelope has to be larger than the card or the insertion line jams. The working rule:

• Add 1/4 in (6 mm) to width and height of the finished folded piece.
• For a thick suite (3 mm or more of stacked stock), push to 3/8 in (9 mm) on the width, because thickness steals clearance.
• For an envelope liner, subtract 1/8 in from the envelope dimensions, and trim the flap shape from a template, not by eye.

So a 5 x 7 folded trifold needs an A7 at 5.25 x 7.25. If your trifold finishes at 5.0625 in wide because the folds pushed out, you are now at 5.3125 in and the A7 is tight. That is the entire reason the next section exists.

Trifold panel math: the part that breaks jobs

A trifold is not three equal panels. When paper rolls in on itself, the inner panel has to travel a shorter distance or it will bulge the fold and widen the finished piece. Build in a fold allowance.

Roll fold (classic trifold) at 5 x 7 finished

Flat sheet: 14.875 x 7 in, folded to 5 x 7.

Panel (left to right on the flat sheet)	Width	Role
Panel 1	4.875 in	Tucks in first, must be short
Panel 2	5.000 in	Middle, carries the main copy
Panel 3	5.000 in	Outer cover, defines finished size

On stock heavier than 270 gsm, increase the allowance on panel 1 to 3/16 in and shave 1/16 in off panel 2 as well. Thick cotton needs more room than digital cover stock.

Gate fold at 5 x 7 finished

Flat sheet: 9.9375 x 7 in. Centre panel 5 in, two outer flaps 2.46875 in each (half of 5 in, minus 1/32 in per flap) so the flaps meet in the centre without kissing or overlapping.

Half fold at 5 x 7 finished

Flat sheet: 10 x 7 in, no allowance needed on light stock, 1/32 in on heavy stock. This is the easiest fold to mail and the easiest to letterpress on one side only.

Fold direction and grain

• Always fold parallel to the grain. Cross-grain folds crack, especially on coated and cotton stock.
• On any stock above 216 gsm (80 lb cover), score before folding. No exceptions on digital toner prints, where unscored folds crack the toner line.
• Score depth: one crease for stock up to 300 gsm, double score (two parallel creases 1 to 2 mm apart) for duplexed or 600 gsm stock.

Card stock weights for each piece of the suite

Paper weight controls three things at once: how the piece feels, whether it folds, and whether it stays under the postal thickness limit.

Stock	gsm	Approx. caliper	Folds?	Best for
80 lb text	118	0.005 in	Yes, no score	Belly bands, vellum wraps, maps
100 lb text	148	0.007 in	Yes, no score	Lightweight trifolds, menus, programs
80 lb cover	216	0.010 in	Score first	RSVP cards, details cards
100 lb cover	270	0.012 in	Score first	Standard flat invitation, sturdy trifold
110 lb cover	300	0.014 in	Score, double on cotton	Premium flat invitation
120 lb cover	324	0.016 in	Double score	Pocketfolds, heavy covers
Duplexed cotton	600	0.032 in	Do not fold	Letterpress, foil, flat cards only

Practical weight pairings for a trifold suite

• Trifold shell: 100 lb cover (270 gsm) scored, or 120 lb cover if it acts as a pocket
• Inserts tucked inside: 80 lb cover (216 gsm) so the stack stays slim
• RSVP card: 80 lb cover minimum, because postal automation needs at least 0.007 in thickness
• Vellum or translucent overlay: 100 to 140 gsm, and remember toner does not fuse well on vellum, so print it on a flatbed or use foil

Mailing: the three limits that decide your design

In the US, a mailpiece qualifies for the standard letter rate only if it stays inside all of these:

1. Size: between 3.5 x 5 in and 6.125 x 11.5 in
2. Thickness: between 0.007 in and 0.25 in, and uniform across the piece
3. Weight: at or under 1 oz for a single stamp, up to 3.5 oz for letters with additional postage

Anything square, rigid, lumpy, clasped, or with an uneven thickness picks up a non-machinable surcharge. Wax seals, ribbons, and tied belly bands all trigger it. That is not a reason to avoid them, just budget for the extra stamp and weigh a finished sample at the counter before you buy postage. Rates change, so confirm current pricing with the carrier rather than relying on a number in a blog post.

Thickness budget worked out

A 5 x 7 trifold suite, measured flat at the thickest point:

• Trifold shell, 270 gsm, three layers at the fold: 0.036 in
• Details card, 216 gsm: 0.010 in
• RSVP card, 216 gsm: 0.010 in
• RSVP envelope, flat: 0.010 in
• A7 outer envelope: 0.010 in
• Total: around 0.076 in, comfortably under the 0.25 in ceiling

Weight is the tighter constraint, not thickness. That same suite typically lands between 0.9 and 1.3 oz depending on stock, which is exactly why 80 lb cover inserts rather than 110 lb cover inserts can save a client hundreds of dollars in postage on a 150 piece mailing.

Building the suite: a step by step walkthrough

1. Lock the envelope first. Buy or confirm stock on the A7 before you design. Envelope availability drives the format, not the other way round.
2. Set the finished folded size at 5 x 7 and work backwards to the flat sheet (14.875 x 7 for a roll fold).
3. Build the document at flat size with 0.125 in bleed on all four sides and a 0.25 in safe margin inside every trim and fold line.
4. Add fold guides, not fold marks inside the artwork. Keep type at least 0.1875 in away from any score, or it will look crooked after folding tolerance.
5. Size the inserts down. Inside a 5 x 7 trifold, inserts should be no larger than 4.5 x 6.5 in so they do not peek out of the folded edge.
6. Check the sheet yield. A 14.875 x 7 flat piece fits two-up on a 13 x 19 sheet if you rotate, or one-up with generous gripper. Confirm with your press before quoting.
7. Print a white paper mock-up at final size, fold it, stuff it, seal it, and weigh it. This single step catches more errors than any preflight.
8. Export PDF/X-4, CMYK, fonts embedded, crop marks on, bleed included, spot colours named consistently if you are foiling or letterpressing.

Common mistakes we see on incoming files

• Three equal panels on a roll fold. The piece ends up 5.0625 in wide and will not insert cleanly.
• Designing at folded size and asking the printer to “just imposition it”. The fold allowance has to live in the design, not the imposition.
• No bleed on fold panels. Background colour that stops at the fold line shows a white sliver on one side.
• RSVP cards under 3.5 x 5 in. They are not mailable on their own, so the reply envelope has to be A1 or larger with a card that fills it.
• Square invitations without a postage check. Beautiful format, guaranteed surcharge.
• Cross-grain folds on cotton. Visible fibre cracking on every piece, and it cannot be fixed after the fact.
• RGB foil files. Foil and letterpress layers should be 100% K vector art on a separate named layer or page.

Quick reference: suite spec sheet

Piece	Finished size	Flat size	Stock
Trifold invitation	5 x 7 in	14.875 x 7 in	270 gsm, scored
Details card	4.5 x 6.5 in	same	216 gsm
RSVP card	4.25 x 5.5 in	same	216 gsm
RSVP envelope	A2, 4.375 x 5.75 in	n/a	120 gsm
Outer envelope	A7, 5.25 x 7.25 in	n/a	120 gsm, optional liner
Belly band	1.5 x 11 in	same	118 gsm or vellum

FAQ

What is the standard size of a wedding invite?

5″ x 7″ (127 x 178 mm) is the standard, and it pairs with an A7 envelope at 5.25 x 7.25 in. Petite formats at 4.25 x 6 in and oversized A8 or A9 cards are the common alternatives. An extended version exists for anyone curious.

Are wedding invites A5 or A6?

In metric markets, both are used. A5 (148 x 210 mm) is the large, formal option and takes a C5 envelope. A6 (105 x 148 mm) is the compact everyday size and takes a C6 envelope. A5 is the closest metric equivalent to the North American 5 x 7 feel, though it is noticeably taller and narrower.

Should wedding invites be 4×6 or 5×7?

Use 5 x 7 when the invitation carries full formal wording, an ornate border, or a trifold layout. Use 4 x 6 when budget or postage weight matters, for save the dates, or for postcard-style replies. If the suite has more than two inserts, 5 x 7 is easier to stuff and looks less crowded.

What are the standard sizes for invitations?

The core set is 3.5 x 5 (A1), 4.25 x 5.5 (A2), 4 x 6 (A6), 5 x 7 (A7), 5.25 x 7.75 (A8) and 5.5 x 8.5 (A9), plus a 5.25 x 5.25 square. Each number corresponds to a stock envelope size, which is why sticking to them keeps costs down.

How much larger should the envelope be than the invitation?

1/4 in (6 mm) larger in both width and height for a single card. Go to 3/8 in on width for thick folded suites, liners, or anything with a wax seal.

What paper weight should a trifold invitation be?

270 gsm (100 lb cover) is the sweet spot: substantial in hand, scores and folds cleanly, and keeps the stack under the letter weight limit. Below 216 gsm the piece feels flimsy. Above 324 gsm you need double scoring and the folded edge starts bulging.

Can a trifold invitation be mailed with one stamp?

Yes, if the folded piece stays within 3.5 x 5 in to 6.125 x 11.5 in, the total thickness stays under 0.25 in, and the stuffed envelope weighs 1 oz or less. A 5 x 7 trifold on 270 gsm with two 216 gsm inserts usually clears it. Weigh a finished sample before buying postage.

Why does my trifold not fit the envelope even though the panels are 5 inches?

Because equal panels on a roll fold push the folded piece wider than 5 in. Shorten the innermost panel by 1/8 in and, on heavy stock, the middle panel by 1/16 in as well.

What resolution and bleed should the file be?

300 dpi at final size, CMYK, 0.125 in bleed on all sides, 0.25 in safe margin from trims and folds, exported as PDF/X-4 with crop marks. For pixel dimensions, a 5 x 7 card at 300 dpi with bleed is 1575 x 2175 px.

Need a second pair of eyes on your dielines?

If you are preparing a suite and want the panel math, scoring, and envelope fit checked before the run, send us the flat artwork with fold guides. Catching a 1/8 in error at proof stage costs nothing. Catching it after 200 invitations are folded costs the whole job. Source: https://womangettingmarried.com.