Envelope Size Guide

Most of us are familiar with an ‘A4’ sheet of paper. The A paper series is within the ISO 216 standard, which is the international standard for paper size.

There are only a few exceptions, for example, North America and some areas of Central and South America. Here the terms ‘legal’ and ‘letter’ are used which you may have noticed in your printer settings.

The envelope sizes UK follow the C series which follow the A series of paper sizing. For example, an A4 sheet of card or paper fits a C4 envelope. The C4 envelope is larger, allowing the paper to fit inside. So paper sizes have an ‘A’ prefix where envelopes have a ‘C’ prefix.

Remember that all envelopes, including wedding envelopes, can be ‘portrait’ or ‘landscape’ with the opening edge being on the short or long side. Those opening on the long edge are ‘banker’ style, whereas those opening on the short edge are called ‘wallet’.

Envelopes can also be gummed or peel and seal both works equally just as well!

If you’re making A6 size wedding invitations, you’ll need a C6 envelope, simple really!

For a quick reference guide to envelope sizes and associated paper sizes view our envelope size charts below.

Popular wedding invitation envelopes for wedding DIY

155mm Square Envelopes

Envelopes for large square card blanks

These square envelopes are perfect for large square pocketfolds or greeting card style invitations and handmade cards. They’re a staple to keep with your card making supplies or card blanks.

155mm square envelope size: 155 x 155mm

C5 Envelopes

C5 Wedding Envelopes

C5 envelopes are for larger wedding invitations, and they fit an A4 paper folded in half. Most would search for an ‘A5 envelope size’ or ‘A5 envelopes’ as this is technically the size of the paper.

We’ve often felt that for wedding stationery there’s a little too much room in these envelopes for an A5 invitation without embellishment or a large ribbon bow. However, they’re ideal if you want to seal your Order of Service in an envelope or use them as booklet envelopes.

For this reason, we’ve introduced a ‘smaller C5 envelope’; we think it fits an A4 sheet folded in half better. We called it smaller ‘C5’ so that you can visualise the size.

Ideal RSVP card envelopes for this envelope are 125mm x 175mm and C6 envelopes.

C5 envelope size: 229 x 162mm

'Small' C5 Envelopes

'Small' C5 Wedding Envelopes

We introduced these envelopes for flat, postcard style invitations that don’t need the slightly larger traditional C5 envelope. They’re perfect for A5 wedding invitations, even those with an RSVP card.

Ideal RSVP card envelopes for this envelope are 125mm x 175mm and C6 envelopes.

Small C5 envelope size: 216 x 152mm

Classic (5 x 7") Envelopes

Classic 5 x 7" Wedding Envelopes

Back by popular demand this size of envelope has become very popular recently. There’s some confusion over the sizing mainly because the 5 x 7″ reference is to the size of the card blank (12.7 x 17.8cm approx) that fits inside not the actual size of the envelope itself.

5 x 7″ envelope size: 133 x 184mm

130mm Square Envelopes

130mm Square Wedding Envelopes

Cute envelopes ideal for postcard style wedding invitations or blank cards that are around 125mm square. Ideal envelope size for evening wedding invitations, Save the Date cards and RSVP cards.

130mm Square Envelope Size: 130 x 130mm

125mm x 175mm Envelopes

125 x 175mm Wedding Envelopes

The portrait envelopes are a good size for wedding invitations and suit either evening or day wedding invitations. RSVP cards in a C6 envelope work well with this size invite.

Envelope Size: 125x 175mm

DL Envelopes

DL 'large tall' Wedding Envelopes

DL envelopes are familiar to most of us as a ‘business envelopes’. An A$ sheet of paper folded on the long edge with two creases fits a DL envelope or an A5 sheet folded once.

DL Envelope Size: 110 x 220 mm

C6 Envelopes

C6 Wedding Envelopes

C6 envelopes are hugely popular for small greeting cards. It’s a budget-friendly size as you can make 4 postcards (or 2 folded card blanks) from an A4 sheet of paper which will then fit a C6 envelope.

Also, an A5 sheet folded on the long edge once (i.e. in half) will fit into a C6 envelope.

C6 Envelope Size: 114 x 162 mm

C7 Envelopes

C7 Wedding Envelopes

These cute little envelopes are perfect for using with RSVP cards or for making small thank you notes and cards.

One sheet of A6 size paper folded or cut in half will fit an A7 envelope.

C7 Envelope Size: 83 x 112 mm

C4 Envelopes

C4 Wedding Envelopes

Perfect for businesses to send documents but also ideal for large cards or craft projects. A3 paper or card folded in half or a flat A4 sheet of paper or card will fit into a C4 envelope. Most people would think of this as an A4 envelope size.

C4 Envelope Size: 229 x 324 mm

Envelope Liners

Glitter envelope liners
Envelope liners are easy to make and are perfect for a luxury wedding invitation

Envelope liners are easy to make from a template and line the inner of the envelope. If you’re making a special handmade card or have a wedding invitation to send they’re not only pretty but add additional protection to what’s inside.

Handmade papers which are often thicker make lovely envelope liners.

Top Tip

Envelopes for DIY wedding invitations
Choosing the best wedding invitation envelope is critical before you even start designing your invitation

If you’re making your own DIY wedding invitations for your big day, always start with the envelope and make your invitation fit inside. It’s much easier to do this than searching for an envelope to fit an already made invitation.

Plan in advance for your wedding invitations and collate your wedding ideas. Decide a date for sending tour invitations in your wedding planning to avoid a last-minute rush.

Remember that although most envelopes are made through a die-cutting process always allow for size tolerance of 2-3mm.

How to make an Envelope out of Paper

155mm Square Envelope Template

155mm Square envelope template
Make your own large square envelopes

125 x 175mm Envelope Template

125 x 175mm envelope template
Make matching envelopes for your wedding invitations

130mm Square Envelope Template

130mm envelope template
Make your own Save the Date card envelopes

C5 Envelope Template

C5 envelope template
Perfect envelopes for larger wedding invitations

C7 Envelope Template

C7 envelope 83x112mm template
Perfect envelopes for A7 RSVP cards

DL Envelope Template

DL envelope template
A template for a business sized enevlope

114 x 162mm Envelope Template

C6 envelope template
C6 envelope template, a very popular size

(7 x 5" envelope) 133 x 184mm Envelope Template

7 x 5 Classic envelope template
Make your own 7 x 5" envelopes

'Small' C5 Envelope Template

Small C5 envelope template
The perfect envelope for an A5 sized wedding invitation

How to make an Envelope Liner

An envelope liner is really easy to make and we have created several templates for you to use with our envelopes. All you need to do is print out the template and cut out then fit into your envelope and fold. Envelope liners add an additional layer of protection for the wedding invitation inside and can be made from matching or coordinating papers.

155 x 155mm Envelope Liner Template

155mm Square Envelope Liner
Make an envelope liner for a large square envelope

(7 x 5" envelope) 133 x 184mm Envelope Liner Template

7 x 5 envelope liner template
Make your own 7 x 5" envelope liners

130 x 130mm Envelope Liner Template

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A template for liners fro 130mm square envelopes