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12x9x4 Mailer Boxes
Custom 12x9x4 Mailer Boxes
Wholesale corrugated Boxes
subscription box packaging
corrugated mailer boxes UK

12x9x4 Mailer Boxes

12x9x4 mailer boxes are a practical and versatile packaging solution for shipping medium-sized products like apparel, books, cosmetics, electronics, or subscription kits. These boxes offer excellent durability and protection without the need for additional tape or adhesives. At The Product Boxes UK, we manufacture custom mailer boxes using high-quality corrugated or kraft material to ensure strength during transit.

You can fully personalise these boxes with your brand’s logo, colours, and artwork using offset or digital printing. Add finishes like matte, gloss, soft-touch, or spot UV to elevate the unboxing experience and reinforce your brand identity. Whether you need minimalist branding or vibrant graphics for retail-ready presentation, we tailor each box to suit your needs. The Product Boxes UK is your go-to partner for high-quality mailer box packaging. So, don’t wait and impress your customers from the moment they receive their order with strong, stylish, and sustainable 12x9x4 mailer boxes.

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Deliver Style and Safety with 12x9x4 Mailer Boxes

Packaging isn’t just about securing a product, it’s about delivering an experience that reflects your brand’s quality, care, and attention to detail. From the moment your customer receives their package, every element should feel intentional. That’s where the 12x9x4 mailer box stands out.

Our custom mailer boxes strike the perfect balance between form and function, offering a clean, compact solution that suits a wide range of industries and product types.

From curated gift sets and subscription boxes to tech accessories, this size is a go-to choice for businesses that want their packaging to make a strong first impression. It’s the smart way to ship with confidence and style.

Why is 12x9x4 size Perfect for Packaging?

The 12x9x4 boxes is one of the most versatile formats in e-commerce packaging. It gives you space to pack a variety of mid-sized products without adding unnecessary shipping cost or space.

Ideal for:

  • Subscription boxes (beauty kits, snacks, curated bundles)
  • Apparel and accessories (T-shirts, scarves, wallets, socks)
  • Skincare sets or small tech items
  • Books and printed materials with added promo items
  • Custom gift boxes or retail product kits

It’s spacious enough for layering, bundling, and branding, yet compact enough to be cost-efficient and user-friendly.

Our Custom Inserts Make the Difference

Don’t let your products shift or get lost in transit. Ecommerce businesses need custom mailer boxes with inserts for better safety and a polished unboxing experience:

  • Cardboard Inserts: Affordable and eco-friendly, ideal for separating products or creating compartments
  • Foam Inserts: A premium option for fragile or luxury items, cut to fit snugly around your product
  • Molded Paperboard Trays: Great for subscription kits or gift sets where visual layout matters
  • Die-Cut Holders: Secure jars, bottles, or devices in place with precision

With the right insert, your products arrive exactly how you intended, secure, attractive, and memorable.

We Use Quality Materials For Extra Protection

Each box is made from durable corrugated cardboard, chosen for its strength, rigidity, and ability to withstand the rigors of shipping and handling. 

At TPB you’ve options to from:

  • E-flute: Lightweight and sleek, perfect for retail-ready finishes
  • B-flute: Thicker and more cushioning, ideal for extra protection
  • Kraft or White Options: Go rustic and raw with natural kraft, or clean and polished with white-coated stock

Custom Boxes Solutions to Make it Only Yours

Your 12x9x4 mailer box isn’t just a container, it’s an extension of your brand. With our advanced printing services, you can turn plain packaging into a bold, branded experience:

  • Exterior and interior printing: Surprise and engage your customers from the moment they open
  • CMYK full-colour prints: Vivid colours, smooth gradients, sharp details
  • Matte, gloss, or soft-touch lamination: Add texture and finish that complements your design
  • Foil stamping, embossing, spot UV: For luxury packaging that demands attention

Need help with artwork or layout? Our design team is ready to guide you from concept to delivery.

Order Your Mailer Boxes in Bulk and Save More

We cover the businesses that cover high volumes with wholesale and bulk pricing on all our mailer boxes. Whether you’re launching a campaign or prepping for seasonal orders, we ensure fast production and consistent quality.

Our streamlined process means:

  • Lower cost per unit in higher quantities
  • Custom inserts bundled with box orders
  • Flexible order minimums to suit small startups or large retailers
  • Reliable delivery across the UK

Why Choose The Product Boxes UK for personalised packaging services?

We’re not just box suppliers, we’re packaging partners.

  • Industry-grade materials
  • Customisation without compromise
  • UK-based production and customer support
  • Rapid turnaround times
  • Eco-friendly options available

We combine craftsmanship with customer care, so your packaging reflects the same quality as your product.

Ready to upgrade your packaging with the perfectly-sized 12x9x4 mailer box? Let us show you how impactful, protective, and brand-forward your box can be.

Type Specification
Product Name 12x9x4 Custom Mailer Boxes
Dimensions (L x W x H) 12 x 9 x 4 inches (30.5 x 22.9 x 10.2 cm)
Box Style Easy Fold Self-Locking Mailer
Material Options E-flute or B-flute corrugated cardboard, white kraft, or natural brown
Board Thickness 1.5 mm to 3 mm (single or double-wall)
Printing Full-color CMYK, PMS spot colors, inside-outside print available
Finish Options Matte, gloss, soft-touch lamination, aqueous coating, UV coating
Closure Type Tuck-in flaps with locking tabs (no tape needed)
Customization Custom sizes, die-cut windows, inserts, QR codes, artwork upload
Logo & Branding Offset, digital or screen printing of logos, slogans, barcodes
Color Options Full-color, kraft brown, premium black, pastel tones, or custom
Use Cases Ecommerce shipping, PR kits, electronics, cosmetics, apparel
Minimum Order Starting from 50 units (bulk discounts available)
Sustainability Recyclable, biodegradable materials, FSC®-certified options
Weight Capacity Up to 5–7 kg (depending on flute type and board strength)
Shipping Format Flat-packed for easy storage and lower shipping costs
Production Time 7–10 business days after design approval

Q. What fits inside a 12x9x4 mailer box?

A. A 12x9x4 inch mailer box is ideal for medium-sized items like clothing sets, books, small electronics, skincare bundles, or subscription kits. The 4-inch depth provides enough internal space for layered or cushioned items without bulging.

Q. Are 12x9x4 boxes a good size for apparel shipping?

A. Yes, 12x9x4 mailer boxes can comfortably fit folded garments such as t-shirts, hoodies, or small clothing bundles. They are widely used by fashion brands for e-commerce deliveries due to their compact and presentable shape.

Q. How much weight can a 12x9x4 mailer box hold?

A. When made from standard E-flute or B-flute corrugated cardboard, a 12x9x4 box can typically hold 3 to 5 kg (6–11 lbs) safely. Heavier-duty board can support more weight if needed.

Q. Is the 12x9x4 box size accepted by courier services?

A. Yes, the 12x9x4 inch size fits well within the dimension limits of major carriers like Royal Mail, USPS, DHL, and FedEx. It helps optimise shipping rates by staying within small or medium parcel categories.

Q. Can I use a 12x9x4 box for gift or retail packaging?

A. Absolutely. The 12x9x4 size is spacious enough for curated gift sets, PR boxes, or retail kits while still looking compact and premium. It’s a common size for brand presentation packaging.

Q. Can I add inserts or partitions to 12x9x4 boxes?

A. Yes, custom inserts such as foam, cardboard dividers, or die-cut trays can be added to organize contents, secure fragile items, and enhance the unboxing experience within 12x9x4 mailers.

Q. Are these boxes deep enough for stacked products?

A. Yes, the 4-inch depth is ideal for stacking 2–3 layers of small products like jars, bottles, pouches, or folded items, especially when combined with protective inserts or wraps.

Q. Can 12x9x4 boxes be custom printed on all sides?

A. Yes, this size offers ample surface area on the lid, side walls, and bottom for full-colour custom printing. You can brand both the interior and exterior panels with artwork, messaging, or instructions.

Q. Are 12x9x4 boxes shipped flat or assembled?

A. These mailer boxes are usually shipped flat-packed to save space. They feature easy self-locking flaps and take only seconds to assemble by hand without any glue or tape.

Q. What is the internal volume of a 12x9x4 box?

A. The internal volume of a 12x9x4 inch box is approximately 432 cubic inches (7.08 litres), offering enough space for multiple medium-sized products or neatly arranged components.

Related Products

Corrugated

A fluted box material is created to enhance the strength of the boxes for shipment purposes.

Cardboard

Light in weight and easy to print cardstock material that would be molded into any shape and style.

Kraft

Slightly brown paper-like thin material for packaging created by wood pulp and heaving eco-friendly nature.

Rigid

A thick cardboard box that is high in strength but also luxurious in presentation.

Holographic

An impressive as well as laminated paperboard that emulates a 3d look to colors.

Offset Print

High-quality and low-cost printing option that transfers the image to the box surface in a good resolution.

Digital Print

Digital printing techniques do not require any sort of printing plate as it transfers the image to the surface of the box easily without a plate.

UV Print

Safeguard the printed area from fading and make them more attractive.

Pantone

Utilization of a universally accepted color-matching system for printing the boxes.

Hot Foil Stamping

Print the foil detail by using the hot dies on the surface of the packaging boxes.

Cold Foil Stamping

It is a removable foil stamp that is applied without pressing any hot die or pressure on the boxes.

Blind Embossing

Create the raised area on the box surface by applying the pressure, not the inks.

Blind Debossing

Just like the craving on the box created by using letter plates or letter presses.

Registered Embossing

Create both the texture as well as the depth and endow a 3d effect to the area of the box.

Combination Embossing

Both the design as well as foiling is utilised at the same time to create a more appealing presentation.

Window Patching

Create a plain see-through cut in the box that is covered with a see-through plastic sheet.

Aqueous Coating

Provide tear-free impact to the packaging with a clear and fast-drying water-based coating at the time of printing.

UV Coating

Add protection against the damaging impact of UV sun rays by applying the UV coating to the packaging.

Spot Gloss UV

Annex the glossy effect on the specific areas of the packaging through spot coating.

Soft Touch Coating

Use the soft touch coating to make the darker and dull areas of the packaging velvety and smooth.

Varnish

Provides protection as well as perfect presentation to the printing part of boxes.

Lamination

A very thin plastic film is pasted in the boxes to make them more durable and long-lasting.

Anti-Scratch Lamination

This thin film of plastic is used to endow the scuff as well as scratch resistance to the boxes.
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