When ordering printed envelopes, you may encounter terms like open side, open top, booklet, or catalog. These terms describe how the envelope opens and how the flap is positioned. Understanding the differences helps ensure you choose the right envelope for mailing letters, sending brochures, or packaging larger documents.
Open Side vs Open Top Envelopes
The first distinction between envelope types is which edge the envelope opens on.
Open Side Envelopes (Long Edge Opening)
An open side envelope opens along the long edge of the envelope.
Characteristics:
- Flap is located on the long edge
- Documents are usually inserted horizontally
- Common for letters, brochures, and marketing materials
The most familiar example is the #10 classic business envelope, which is typically used for mailing standard folded letter sheets.
Open Top Envelopes (Short Edge Opening)
An open top envelope opens along the short edge.
Characteristics:
- Flap is located on the short edge
- Documents slide in vertically
- Ideal for larger or thicker materials
Open top envelopes are often used when documents are not folded, such as reports, booklets, or catalogs.
Why the Terms Can Feel Counter-Intuitive
Many envelopes are wider than they are tall. When you hold them in a landscape orientation, the longer edge naturally appears to be the top of the envelope.
However, envelope terminology comes from the manufacturing perspective, not how the envelope is typically held.
In envelope manufacturing:
- Side refers to the long dimension of the envelope
- Top refers to the short dimension of the envelope
Because of this naming convention:
- Open side envelopes open on the long edge
- Open top envelopes open on the short edge
Even though the longer edge may look like the “top” when viewing the envelope horizontally, it is technically referred to as the side in envelope construction.
A simple way to remember this is:
- Open Side = Long Edge Opening
- Open Top = Short Edge Opening
Booklet vs Catalog Envelopes
The terms booklet and catalog describe specific envelope styles that correspond to these opening directions.
Booklet Envelopes
Booklet envelopes are open side envelopes, meaning they open along the long edge.
Key features:
- Flap located on the long edge
- Wide opening makes inserting materials easier
- Often used for brochures, booklets, and presentation materials
Because the opening runs along the longer side, it is easier to insert larger printed pieces without bending or damaging them.
Common booklet envelope sizes include:
- 6″ × 9″
- 9″ × 12″
- 10″ × 13″
These envelopes are commonly used for marketing materials, reports, and document packages.
Catalog Envelopes
Catalog envelopes are open top envelopes, meaning they open along the short edge.
Key features:
- Flap located on the short edge
- Documents slide in from the top
- Designed for heavier or bulkier materials
Catalog envelopes are built for durability and are commonly used for:
- Manuals
- Product catalogs
- Multiple-page reports
- Large document mailings
Common catalog envelope sizes include:
- 6″ × 9″
- 9″ × 12″
- 10″ × 13″
Even though the sizes may be the same as booklet envelopes, the opening direction is what distinguishes them.
Quick Comparison
| Envelope Style | Opening Edge | Flap Location | Typical Use |
|---|---|---|---|
| Open Side | Long edge | Long edge | Letters, brochures |
| Open Top | Short edge | Short edge | Reports, thick documents |
| Booklet | Long edge (open side) | Long edge | Booklets, presentations |
| Catalog | Short edge (open top) | Short edge | Catalogs, manuals |
Choosing the Right Envelope
When selecting an envelope style, consider how the contents will be inserted and handled.
Booklet envelopes (open side) are usually preferred for:
- Brochures
- Marketing materials
- Presentation documents
Catalog envelopes (open top) are better suited for:
- Thick document stacks
- Manuals or reports
- Materials that slide in vertically
Conclusion
Many envelope sizes such as 6″ × 9″, 9″ × 12″, and 10″ × 13″ are available in both booklet and catalog styles. The difference isn’t the size; it’s which edge the envelope opens on.
Remember:
- Booklet = Open Side = Long Edge Opening
- Catalog = Open Top = Short Edge Opening
Understanding these simple distinctions can help ensure your documents are mailed securely, inserted easily, and presented professionally.
For help printing your business envelopes, feel free to check out Smart Resolution’s custom printed envelopes.
