C6 PiP Box (Mini Postal)
160 × 110 × 20mm — Perfect for fine jewellery, enamel pins, keychains, phone cases, watches, and gift cards.
PiP Postal BoxesCustom Printed PiP Boxes Letterbox-Friendly Postal Packaging
Slimline corrugated postal boxes engineered to qualify for Royal Mail Large Letter rates. Cut UK shipping postage costs by over 50% while delivering a flawless, full-colour branded unboxing right through your customer’s letterbox.
Your specification. Your artwork. A clear quotation.
Quality Specification 
Consider The Details
What are PiP boxes and why are they essential for UK e-commerce?
PiP stands for "Pricing in Proportion" — a standard framework created by Royal Mail that calculates postage based on dimensions rather than just weight. A standard UK parcel costs upwards of £3.29 to ship, whereas a package qualifying as a Royal Mail Large Letter (maximum 353 × 250 × 25mm and up to 750g) costs as little as £1.55. QPack’s custom PiP boxes are precision-die-cut with an external depth strictly under 24mm, guaranteeing your shipments glide through standard UK letterboxes without missed deliveries, courier surcharge penalties, or Royal Mail re-categorisation fees. Starting from just 100 units with flat-pack storage and instant fold-up assembly.
Strictly under 24mm depth — guarantees Royal Mail Large Letter postal qualification
Saves up to £1.74 per package in UK delivery courier postage costs
Fits through 99% of UK residential front door letterboxes — zero missed deliveries
Ships completely flat-packed — stores compactly and pops together in 5 seconds with no tape needed
Technical Matrix
Standard Production Specifications
- Max Depth
- Strictly 24mm (Under 25mm)Qualifies as Royal Mail Large Letter
- Standard Sizes
- C6 (160x110x20mm) · C5 (220x160x20mm)C4 (320x230x20mm) · Custom sizes
- Flute Grade
- Rigid E-Flute (1.5mm)White or Natural Kraft outer
- Print Options
- Full-Colour CMYK (Outside & Inside)Matte or Gloss protective varnish
- Min. Order
- From 100 unitsBest value pricing at 1,000 units
- Lead Time
- 5–7 working daysExpress UK dispatch available
Find your fit
Engineered for UK Postal Savings
Precision-engineered sizes tailored to standard UK paper sizes, flat accessories, and compact retail products.
C5 PiP Box (A5 Letterbox)
220 × 160 × 20mm — Our most popular format. Ideal for skincare kits, A5 booklets, phone accessories, small cosmetics, and scarves.
C4 PiP Box (A4 Large Letter)
320 × 230 × 20mm — Fits folded apparel, T-shirts, lingerie, A4 art prints, calendars, documents, and subscription kits.
Mini Square PiP (C7 Size)
100 × 100 × 20mm — Ultra-compact postage saver for single stud earrings, rings, badges, sample cosmetics, and craft items.
Deep PiP Mailer (Max 24mm)
Custom width and length with maximum 24mm outer clearance — engineered for small books, games, and phone gadgets.
PiP with Custom Fitment
Internal die-cut card insert holding fragile items (bottles, compacts, flash drives) rigidly in place without increasing depth.
Pricing in Proportion Specialists
PiP Postal Boxes: Royal Mail Large Letter & Small Parcel Formats
Postage costs represent one of the largest ongoing expenses for UK e-commerce businesses. A package that exceeds Royal Mail's 25mm Large Letter depth threshold by even a single millimeter jumps directly into the significantly higher Small Parcel tariff, eroding gross profit margins. QPack manufactures precision-die-cut Pricing in Proportion (PiP) postal boxes calibrated strictly within Royal Mail dimensional tolerances. Constructed from rigid, lightweight micro-flute corrugated board with crush-resistant roll-over edges, our PiP boxes fit effortlessly through standard UK domestic letterboxes.
01 Why UK Online Sellers Choose QPack PiP Postal Boxes 5 Standards
Combining rigorous postal compliance with high-definition branding, our PiP boxes protect your margins and impress your customers.
01
Rigid E-Flute Corrugated Protection
Made from rigid 1.5mm E-flute board with high crush resistance — items arrive immaculate without bulk.
02
Full-Colour Inside & Outside Print
Turn a standard postal carton into a luxury unboxing experience. Print vibrant CMYK artwork on the exterior and a warm welcome note inside the lid.
03
Self-Locking Roll-End Construction
Folds together in seconds along pre-creased scorelines. Double-wall side tabs interlock securely without adhesive tape.
04
100% Recyclable & Plastic-Free
Manufactured from FSC-certified sustainable wood pulp. 100% kerbside recyclable, biodegradable, and printed with water-based inks.
05
Low MOQ from 100 Units
Order trial runs from 100 units to test new products, or scale up to 1,000+ units for massive cost-per-box volume savings.
02 Royal Mail PiP Dimensioning & Clearance Margins 01
Engineered to pass Royal Mail postal sizing templates with 100% reliability:
- C4 Large Letter PiP Box (345mm x 240mm x 22mm): Maximum allowable surface area for A4 documents, clothing, fashion accessories, and flat gift sets.
- C5 Large Letter PiP Box (240mm x 165mm x 22mm): Compact letterbox format ideal for mobile phone cases, jewellery, cosmetics, and small electronics.
- C6 Large Letter PiP Box (165mm x 115mm x 22mm): Pocket-sized postal box for USB drives, badges, pin badges, seeds, and micro-skincare bottles.
- The Critical 24mm Safety Ceiling: We engineer all Large Letter boxes with a 22mm–24mm outer depth to allow for board tolerance and slight pack bulging.
03 Board Grammage & Lightweight Engineering 02
Protecting contents without adding expensive postal weight:
- 1.5mm Micro-Flute Corrugated Board: Rigid fluted core providing exceptional edge-crush strength while keeping tare weight under 45 grams.
- Double-Wall Side Flaps: Reinforced folding side walls that prevent the box from bowing outwards and exceeding the 25mm slot limit.
- Smooth White & Natural Kraft Liners: Choose between crisp coated white outer liners for vivid colour printing or eco-friendly brown Kraft.
- Crush-Proof Corner Geometry: Absorbs sorting office belt impacts and letterbox drop shocks without corner buckling.
04 Branding Options & Unboxing Aesthetics 03
Making letterbox delivery exciting for online shoppers:
- Full-Colour Exterior Litho Printing: High-definition 2400 DPI photographic printing on the top lid and perimeter panels.
- Interior Surprise Message Printing: Print custom discount codes, social media tags, or thank-you messages on the inside lid.
- Anti-Scuff Matte Coating: Repels sorting machine scuffs, dirt, and transit dust during Royal Mail sorting.
- Peel-and-Seal Tape & Pull Strips: Optional self-adhesive closure strip providing tamper-evident transit security.
05 Fulfillment Economics & Sizing Advice 04
Maximizing your e-commerce shipping margins:
- Eliminate Missed Delivery Redelivery Fees: Letterbox delivery ensures 100% first-time delivery success, reducing customer service tickets.
- Calculate Product Swell Factor: When packing soft textiles, ensure the item does not push the top lid above the 25mm limit.
- Minimum Orders from 100 Units: Start shipping in professional branded PiP boxes without huge warehousing commitments.
- Next-Day Mainland UK Dispatch: Carefully packed flat in shrink-wrapped bundles for compact, dust-free warehouse storage.
Bespoke UK Production Key Standards At A Glance
- 100% Quality Checked Prior to Dispatch
- Free 3D Digital Simulation & Dieline
- Certified Food-Safe & FSC Materials
- Tracked Mainland UK Delivery Included
HOW IT WORKS
Our 4-Step Packaging & Production Process
From initial idea to your doorstep, here is how easy it is to order custom packaging with QPack.
01 TELL US YOUR SPECS
Tell Us What You're Packing
Tell us your product size and quantity. We give you the exact box dimensions and a free template for your design.
02 FREE 3D PROOF
Free 3D Artwork Proof
Send us your logo or artwork. We create an interactive 3D digital model so you can check your box before printing.
03 VIBRANT PRINT
High-Definition Printing
Your boxes are printed in vibrant color and pre-creased so they fold up quickly with crisp, clean corners.
04 DOORSTEP DELIVERY
Quality Check & Fast Delivery
Every batch is inspected for quality, packed flat to save your storage space, and shipped tracked to your door.
Clear Answers
Frequently Asked Questions
Clear answers on sizing, minimum order runs, artwork proofs, board calipers, and free tracked UK delivery.
What dimensions qualify for Royal Mail Large Letter rates?
Royal Mail Large Letter format allows maximum dimensions of 353mm (Length) × 250mm (Width) × 25mm (Thickness), with a maximum weight of up to 750g. Our PiP boxes are built with a maximum outer thickness of 20mm to 24mm, ensuring they easily pass through the Royal Mail test gauge even with slight parcel bulging.
How much money can a business save using PiP boxes?
Standard Royal Mail Small Parcels cost approximately £3.29+ to send, whereas Large Letters cost from £1.55 (2nd Class) to £2.10 (1st Class). Sending 500 parcels a month in PiP boxes rather than small parcel boxes can save your business over £800 to £1,000 every single month in courier postage alone!
Do custom PiP boxes require tape or glue to seal?
The box itself locks together tightly using roll-end tuck tabs without any glue or tape. When dispatching to your customer, a simple branded sticker seal or 1 strip of kraft packaging tape across the front closure tab is all you need.
Can I print inside the lid of my PiP box?
Yes! Inside lid printing is one of our most popular choices. It allows you to display a welcoming brand message, thank-you note, social media handle, or QR code that catches the recipient’s eye the moment they open the box.
How are the PiP boxes delivered to me?
All PiP boxes are delivered 100% flat-packed in compact cartons. 500 to 1,000 boxes take up very little shelf or warehouse space and assemble effortlessly in just 5 seconds.
What is the minimum order quantity (MOQ)?
Our minimum order starts from just 100 units. Since setup and digital machine calibration costs are fixed, unit rates improve substantially at 1,000 units. Request a fast free quote today to compare tier pricing.
Have a specific requirement or custom dieline?
Our UK packaging specialists can verify bottle clearances, create tailored structural CAD dielines, and supply physical plain samples.
Let’s make it yours
Ready to Cut Your UK Shipping Costs?
Get a free, instant PiP postal box quote within 24 hours. Tell us your product size and quantity — we will calculate your exact unit price and Royal Mail savings.