Paper Envelopes: How to Choose the Right Size, Closure Type and Quantity

A poorly chosen envelope can quickly turn a simple task into an unnecessary expense. An A4 document slipped into a size that's too narrow, a closure that doesn't hold properly, or paper that's too flimsy can spoil both the presentation of your mail and its protection.

Before buying paper envelopes, three mistakes crop up time and again:

• Relying solely on the picture: on screen, a white envelope can look thick or rigid. In reality, it's the paper weight and dimensions that determine what it's suitable for.
• Confusing the sizes: a C6, DL or C4 envelope isn't designed for the same documents. A card, a folded letter or an unfolded A4 sheet all need different dimensions.
• Overlooking the closure and quantity: a gummed closure works for occasional use, whereas a self-seal envelope saves time when you need to prepare a batch of mail. For regular professional use, a small pack can also push up the unit price.

The key factors to check before buying paper envelopes

1. Size: C6, DL, C4 or small format

The size must match the contents, while leaving enough margin to insert the document without unnecessary folding.

• C6 envelopes — 114 × 162 mm: these are suitable for an A4 sheet folded into four, cards, invitations and personal correspondence.
• DL envelopes — 110 × 220 mm: these are designed to hold an A4 sheet folded into three. This is the standard size for letters, invoices, administrative mail and bulk mailings.
• C4 envelopes — 229 × 324 mm: these allow you to send an A4 sheet without folding it. They're ideal for reports, posters, drawings, folders and professional documents.
• Small format 90 × 140 mm: these can hold a business card, a photo, a short note or a gift card.

Also check whether you need a window envelope or a plain one. The former makes it easy to display an address printed on the document, while the latter offers a more versatile presentation and greater freedom for writing or sticking on a label.

2. Paper weight and type

Paper weight is expressed in g/m². It refers to the weight of the paper per square metre, but on its own it doesn't determine its strength or finish.

• 90 g/m²: a common all-round choice for letters, documents and everyday mailings.
• 100 g/m²: a more substantial paper, ideal for invitations, announcements and particularly polished correspondence.
• Laid paper: its visible lines give it a classic texture and a more refined appearance.
• Kraft paper: its brown, natural look is well suited to sending folders, creations, magazines or documents that need a tougher paper.

For regular use, also look out for any certifications. Products may carry an FSC or PEFC certification, which relates to the responsible sourcing of fibres according to the manufacturer's stated standard. This mention doesn't replace the need to check the dimensions, paper weight and closure type.

3. Closure type

Self-seal white envelopes usually have an adhesive strip protected by a peel-off film. They're handy for preparing several items of mail quickly, without having to moisten the flap.

Gummed envelopes have an adhesive strip that needs to be moistened. They're suitable for classic correspondence or invitations, provided they're stored in a dry place to prevent premature sticking.

For a business, association or school, compare the number of envelopes per pack and how easy they are to store. A pack of 25 is enough for an occasional need, while a larger quantity will often be more practical for regular use.

Our selection based on your usage profile

Recommended for: Beginners on a budget

CLAIREFONTAINE 9915C – Pack of 25 white DL envelopes

Why this choice suits this profile: The DL format of 110 × 220 mm is ideal for letters and A4 documents folded into three. The pack of 25 covers a typical need at home, school or the office.

How this product avoids the pitfall

Its dimensions and 90 g/m² paper weight are clearly stated. So there's no risk of choosing an envelope based on its appearance alone.

Key benefit and highlights

90 g/m² white Clairefontaine paper, self-seal closure protected by a silicone strip and FSC certification stated.

Recommended for: Premium enthusiasts

CLAIREFONTAINE LALO – Pack of 25 C6 laid paper envelopes

Why this choice suits this profile: The 100 g/m² white laid paper offers a visible texture, perfect for invitations, announcements, menus or thank-you notes.

How this product avoids the pitfall

The texture, C6 size and gummed closure are all specified, so you can check they're right for event correspondence.

Key benefit and highlights

French laid paper at 100 g/m², lined texture and gummed flap for sealing.

Recommended for: Specific uses and heavy users

CLAIREFONTAINE 75015C – Pack of 15 C4 kraft envelopes

Why this choice suits this profile: The C4 format of 229 × 324 mm holds an A4 sheet without folding. It meets the needs of businesses, schools, artists and administrative departments.

How this product avoids the pitfall

Its size is designed for flat documents, which avoids unnecessary creases and envelopes that are too small for A4 folders.

Key benefit and highlights

90 g/m² Milleraies kraft paper, self-seal closure and PEFC certification stated.

Recommended for: Gifts and traditional celebrations

Small Chinese red Hongbao envelopes – pack of 6

Why this choice suits this profile: These gift envelopes are intended for cash presents during Lunar New Year, a wedding, birthday or other celebration.

How this product avoids the pitfall

The pack size and intended use are clearly stated. This stops you from picking an ordinary envelope for a cultural or festive occasion.

Key benefit and highlights

Red paper, small format and pack of 6 envelopes designed for cash gifts.

Buying tips by use

For envelopes intended for letters, go for the DL format if the A4 sheet is folded into three. For an invitation or a card, the C6 format offers a suitable size and is available in white, laid or decorative paper.

For professional documents, check for a self-seal flap and choose the C4 format if you want to keep sheets flat. Kraft envelopes are also a good option when you're after a natural look and a tougher paper.

For gift envelopes, finally, Chinese red envelopes, hongbao and decorated designs serve a different purpose from postal mail. Before ordering, check the number of pieces, the finish and the interior capacity.

Frequently asked questions about paper envelopes

Which envelope should I choose for an A4 sheet folded into three?

The DL format of 110 × 220 mm is generally designed to hold an A4 sheet folded into three. It's particularly suitable for letters, invoices and administrative mail.

What's the difference between a gummed envelope and a self-seal envelope?

A gummed envelope is sealed by moistening the adhesive strip on the flap. A self-seal envelope has a protected strip that you simply uncover before pressing the flap down. The latter is often more practical for preparing a large number of items of mail.

How long can paper envelopes be stored?

The storage life depends above all on the storage conditions. Keep them flat, in a dry place, away from moisture and direct sunlight. For gummed models, these precautions help reduce the risk of premature sticking and warping. For self-seal models, they help preserve the effectiveness of the adhesive strip.