What Size Should Invitations Be? A UK Guide

The first thing guests notice is often not the wording, but the feel of the envelope in their hand. Too small, and important details can feel cramped. Too large, and postage, envelopes and presentation can quickly add to the cost. So, what size should invitations be? For most celebrations, an A6, 5 x 7 inch or square invitation offers the best balance of space, style and affordability.

The right choice depends on your occasion, the amount you need to say and whether you are including extra cards. A simple children’s party invitation has very different needs from a formal wedding day invitation with RSVP, gift and accommodation information. Choosing the size early makes personalising every detail much easier.

What size should invitations be for most events?

For everyday celebrations, A6 invitations measuring 105 x 148 mm are a popular and practical choice. They are compact but still give you plenty of room for names, dates, times, locations and a short message. This size suits birthday parties, baby showers, christenings, holy communions, anniversaries and thank you cards particularly well.

A6 cards are easy to post, comfortable to hold and look lovely in both portrait and landscape designs. They also work beautifully when you want a bright, photo-led or themed design without creating a large stack of stationery for guests to store.

For occasions with more detail or a more formal feel, 5 x 7 inch invitations, around 127 x 178 mm, are a favourite. They offer additional room for ceremony and reception timings, a dress code, a touching message or fuller venue information. This is why they are often chosen for weddings, engagements, milestone birthdays and retirement celebrations.

Neither size is automatically better. A6 keeps things neat and cost-conscious, while 5 x 7 inches creates more presence and breathing space on the page.

Popular invitation sizes in the UK

A6: 105 x 148 mm

A6 is one of the most versatile invitation sizes available. It feels special without being oversized, and it works for relaxed family gatherings as well as smarter occasions. If you are planning a child’s birthday, a baby reveal or an afternoon tea for an anniversary, it gives you everything you need without overcomplicating the design.

It is also a sensible option when you have a longer guest list. Smaller cards generally use less card and may help keep envelope and postage costs more manageable. That said, always check the final packed weight and envelope dimensions before posting, especially if you are adding inserts or decorative finishing touches.

5 x 7 inches: 127 x 178 mm

A 5 x 7 inch card has a classic, generous look. It is ideal when the invitation is the main piece of stationery and needs to carry more information. Wedding invitations often benefit from this extra space, particularly if you want to include both ceremony and evening reception details, a request for RSVPs and a short personal note.

This size also allows elegant design elements to breathe. Watercolour florals, formal typography, family photographs and illustrated venues can look less crowded than they might on a smaller card. The trade-off is that larger cards can cost a little more to print and post, so it is worth deciding whether the extra room will genuinely be used.

Square invitations: commonly 148 x 148 mm

Square invitations feel modern, cheerful and immediately eye-catching. They are especially lovely for baby showers, children’s birthdays, engagement parties and celebrations with a bold theme. A square card gives a centred, balanced layout that works well for photographs, wreath designs and large names or numbers.

Before choosing a square format, think about envelopes and posting. Square envelopes can sometimes fall outside standard postal dimensions or cost more than rectangular alternatives. They are a wonderful choice when presentation is your priority, but do factor in the practical side if you are sending many invitations through the post.

A5: 148 x 210 mm

A5 invitations are larger and more statement-making. They can be a good fit for formal weddings, gala-style celebrations, memorial events or occasions where guests need substantial information in one place. They also suit designs with a large photograph, meaningful poem or detailed itinerary.

For most party invitations, though, A5 may be more space than you need. It can increase postage costs and may feel less convenient for guests. If you love the idea of a grander card but only have a few lines of wording, a 5 x 7 inch option often gives a similarly special result with less empty space.

DL: 99 x 210 mm

DL invitations are slim, elegant cards often associated with contemporary weddings, evening events and formal dinners. Their tall shape suits minimal designs, fine-line florals and carefully arranged wording. They fit a business-style envelope, which can make them feel polished and distinctive.

They are less flexible for landscape photographs or lots of text, however. Choose DL when the design is intentionally clean and the key details can be kept concise.

Match the card size to your wording

The size of your invitation should make the information easy to read at a glance. Guests should not have to search for the date, wonder which venue to attend or squint at a tiny RSVP deadline. A beautiful design still needs to do its most important job: clearly invite people to celebrate with you.

For a straightforward party, you usually need the host’s name, the occasion, date, time, address and RSVP details. An A6 card is generally ample. If you are inviting guests to a wedding, however, you may need names, ceremony time, reception details, a dress code, meal choices, transport advice or a website reference. A larger card, or a matching information insert, gives you more freedom.

Avoid squeezing every detail onto one card simply to keep the set small. A main invitation with a separate RSVP card or information card can feel organised and thoughtful. It also lets guests keep the key invitation while returning the RSVP. For weddings and larger events, this approach is often clearer than choosing an oversized invitation.

Think about envelopes, postage and finishing touches

An invitation is not just the card itself. The envelope, RSVP card, belly band, wax seal, ribbon and any additional inserts all affect the final size and weight. A design that looks perfect on screen can become awkward to post if the finished set is too thick or does not fit neatly into its envelope.

Start by deciding whether your guests will receive one card or a full stationery set. If there are multiple pieces, choose an envelope that leaves a little room around the edges without making the contents slide about. Very tight envelopes can bend card corners, while very large ones can make a carefully presented invitation feel less considered.

For any posted invitation, check the current Royal Mail guidance for the finished envelope rather than relying on the card dimensions alone. Postal categories are based on size, thickness and weight. This is particularly useful for square cards, layered designs and invitations with embellishments.

If you are hand-delivering locally, postage matters less, and you can be more adventurous with unusual shapes or added details. Even then, make sure the invitation is easy for guests to carry home and store until the event.

Choose a size that suits the occasion

Formal events tend to suit larger or more structured formats, but there are no fixed rules. A small A6 wedding invitation can look wonderfully refined with quality card, beautiful typography and a carefully chosen colour palette. Equally, a bright 5 x 7 inch card can make a child’s birthday party feel exciting from the moment it arrives.

For a christening, communion or memorial gathering, many families prefer an understated A6 or 5 x 7 inch card that feels respectful and easy to keep. For a baby shower, gender reveal or milestone birthday, a square format can bring out the fun of a playful theme. Save-the-date cards are often smaller because they only need to share the essentials, while thank you cards can be selected for the message you want to write inside.

The best size is the one that reflects your event without creating extra stress for your budget, wording or posting plan.

A simple way to make your decision

If you want a safe, all-round choice, start with A6. It is practical, attractive and suitable for almost every kind of celebration. Move up to 5 x 7 inches if you have more details to include, want a formal look or would like a larger design feature. Choose square or DL when the shape is an intentional part of your style, and select A5 only when the event and wording genuinely call for a larger card.

At Bespoke Candy Delights, we believe your invitations should feel personal from the first glance, without making your planning harder or more expensive. Pick a size that gives your message room to shine, then let the colours, wording and details make it unmistakably yours.