9 Envelopes Printing
Need sleek, branded envelopes for sending contracts, brochures, or official letters? At Custom Boxes Lab, we specialize in #9 envelopes printing that balances professional appeal with reliable function. Whether you’re handling business replies, internal documents, or promotional inserts, our #9 envelopes deliver with sharp printing and secure sealing. So, order your #9 envelopes from Custom Boxes Lab and send every message wrapped in polished presentation.
Availability: In Stock

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Designed for Reply Mail and Business Communication
#9 envelopes (3.875″ x 8.875″) are slightly smaller than standard #10s and commonly used for reply mail or enclosures. They fit perfectly inside a #10 envelope.
Materials
We use high-quality paper stocks built for consistent performance:
- 24 lb. White Wove – Lightweight and smooth for everyday mailing
- 28 lb. Premium Paper – Thicker stock for upscale branding
- Kraft Paper – Rustic, natural look with recyclable appeal
- Security-Tint Options – Keeps private data from showing through
Sizes
Standard #9 size is ideal for inserts and return envelopes:
- #9 regular (no window) for internal use or customer response
- #9 window for return forms and address alignment
- Custom options available upon request
Printing
Print your #9 envelopes to reflect your brand or message:
- One-color to full-color printing
- Logos, return address, taglines, or call-to-actions
- Front-only or flap printing options
We use USPS-compliant, smudge-resistant inks for high-speed handling.
Add-ons
Add functionality or security with these finishing touches:
- Self-seal or peel-and-seal closures
- Security tint patterns
- Custom window placement
- Foil stamping or embossing for high-end mail
Types of #9 Envelopes
Common across offices, direct mail campaigns, and financial correspondence:
- Reply or Return Mail Envelopes
- Billing and Payment Enclosures
- Statement and Form Envelopes
- Donation or Survey Reply Mailers
- Event RSVP Inserts
3Ps of Envelope Printing and Design
- Presentation
Crisp logos and clean text make your mail look polished and trustworthy, boosting open and response rates. - Preservation
Durable paper and secure seals protect your contents from wear and mailing damage. - Protection
Security tints and snug enclosures keep sensitive information private during transit.
Go Premium with Finishing Options
Upgrade your #9 envelopes printing with:
- Custom paper colors or textures
- Soft-touch or matte finishes
- Matching letterhead or insert sets
Why Choose Custom Boxes Lab?
We deliver #9 envelopes printing with precision, speed, and brand consistency—ideal for modern mailing.
- Free design support and layout assistance
- Short runs or large-volume printing
- Eco-friendly paper and ink options
- Fast turnaround and nationwide delivery
- Trusted by marketing teams, offices, and nonprofits
Get a Quote Today
Need envelopes that communicate trust and professionalism? Call us at 0000 or email us now to print your #9 envelopes—smartly designed, securely sealed, and ready to mail.
Dimensions | All Custom Boxes & Shapes, Paper Bags, Mylar Bags, Tube Packaging |
Availability | InStock |
Printing | No Printing, CMYK, CMYK + 1 PMS Color, CMYK + 2 PMS Colors |
Paper Stock | 10pt to 28pt (60lb to 400lb) Eco-Friendly Kraft, E flute Corrugated, Bux Board, Cardstock, Mylar, Paper Bag Stock, Tube Paper, Bespoke Packaging Materials |
Quantities | No Minimum Order Required |
Coating | Gloss, Matte, Spot UV, Holographic Foiling, Gold Foiling, Embossing, Silver Foiling, Debossing |
Default Process | Die Cutting, Gluing, Scoring, Perforation |
Options | Custom Window Cut Out, Gold/Silver Foiling, Embossing, Raised Ink, PVC Sheet, Bespoke Die-Cuts |
Proof | Flat View, 3D Mock-up, Physical Sampling (On request) |
Turn Around Time | 7-10 Business Days, Rush Available |
When measuring a custom box, there are a few technical specifications that must be considered to ensure proper design, manufacturing, and fit for the product. Here are the major technical things to measure a custom box:
Inside Dimensions (Critical for Product Fit)
- Length (L): The longest side of the box measured inside from one corner to the opposite corner.
- Width (W): The shorter side of the box measured inside perpendicular to the length.
- Depth/Height (D or H): Measured inside from the bottom to the top opening of the box. Always specify that dimensions are given in Length × Width × Height.
Outside Dimensions (Important for Shipping & Storage)
- Measure the outer surfaces of the box including material thickness.
- Outside measurements are used for pallet stacking, warehouse spacing, and shipping compliance.
Material Thickness (Board Caliper)
- The thickness of the packaging material (e.g., corrugated board, rigid stock, cardstock).
- Impacts both the internal usable space and external dimensions.
Flap Measurements
- For boxes with flaps (e.g., mailer or shipping boxes), measure:
- Inner flaps: Ensure they meet in the middle without overlapping too much.
- Outer flaps: Allow proper sealing without gaps.
Tolerances
- Account for manufacturing tolerances (usually ±1/16" or ±2mm depending on material).
- Ensure the product fits without being too tight or loose.
Volume Capacity
- Calculate internal cubic capacity (L × W × H).
- Helps in determining how much space the product will occupy and shipping efficiency.
Product Orientation
- Decide how the product sits inside the box and measure accordingly.
- Orientation affects whether length or width is the primary dimension.
Die-Cut Openings or Windows
- Measure exact placement, height, and width for any cutouts.
- Ensure structural integrity when adding windows.
Printing Bleed & Safe Zones
- Include measurements for:
- Bleed area: Extra space beyond the cut line for printing.
- Safe zone: Inner area where critical text or logos should be placed.
Closure Type & Locking Tabs
- Measure slots, tabs, or locks for boxes with custom closures.
- Precision is required to avoid misalignment during assembly.
Packaging Style
- Folds, creases, and scores must be measured for accurate dieline creation.
- Different styles (e.g., RSC, tuck-end, mailer, sleeve) require specific panel measurements.
Delivering Premium Packaging. Materials Tailored for Your Brand and Product.

Cardboard
Giving cardboard material option to give versatility and durability to your box, widely used in many industries.

Kraft
Offering eco-friendly kraft material for your product with the least environmental impact and minimizing waste.

Rigid
Offering you premium rigid boxes, perfect for luxury packaging and high-end presentation.

Corrugated
Custom Boxes Lab specializes in strong, reliable corrugated boxes ideal for shipping and storage.