Quick Answer: Polymailers for e-commerce should be 5–8 cm wider and 10–15 cm taller than the folded product inside. Standard film thickness is 50–70 microns for most clothing and soft goods; heavier or sharp-cornered items need 70–90 microns. Custom-printed polymailers cost only marginally more than plain ones and turn every delivery into a branded touchpoint.
E-commerce is one of the fastest-growing commercial sectors in Bulgaria and across Europe, and the physical packaging of online orders has become a genuine competitive differentiator. The parcel that arrives at a customer’s door is often the first tangible experience they have with your brand. For products that do not require rigid box packaging — clothing, textiles, accessories, books, and flat goods — courier envelopes and polymailers are the most practical and cost-effective solution.
What Are Polymailers and Courier Envelopes?
Polymailers are lightweight, flexible bags made from polyethylene film, designed specifically for shipping. They are sealed with a self-adhesive strip, require no tape, and are water-resistant by nature. Most polymailers also include a secondary adhesive strip so the recipient can reseal the bag if returning an item — a feature that has become standard in the European e-commerce market.
Courier envelopes with a rigid backing include a cardboard or foam insert to protect documents, certificates, or flat items that must not be folded in transit. Both types are available in plain white or black, or can be custom-printed with your brand identity.
How to Choose the Right Size
The polymailer should be approximately 5 to 8 cm wider and 10 to 15 cm taller than the folded product inside. This allows for a clean, flat seal at the top without putting tension on the seam. For businesses shipping multiple product sizes, stocking two or three standard envelope sizes is common practice to cover the full range of orders without overpacking smaller items.
Polymailers that are too large create excess material that folds and bunches, looking unprofessional and sometimes causing issues with automated sorting systems at courier companies. Polymailers that are too small risk tearing at the seams or leaving the self-adhesive strip unable to close properly.
| Product Type | Typical Folded Size | Recommended Polymailer Size |
| T-shirt / single garment | ~30 × 40 cm | 35 × 45 cm |
| 2–3 folded garments | ~35 × 45 cm | 40 × 55 cm |
| Jacket / bulky item | ~40 × 50 cm | 45 × 60 cm |
| Books / flat accessories | ~25 × 35 cm | 30 × 42 cm |
| Shoes (boxed) | ~35 × 20 × 12 cm | 40 × 55 cm (gusseted) |
Table 2: Recommended polymailer sizes by product type. Add 5–8 cm width and 10–15 cm height to the folded product dimensions as a baseline.
Thickness and Durability: Getting the Specification Right
Standard courier envelopes are produced in thicknesses ranging from 50 to 90 microns. For lightweight, non-fragile items like clothing, 50 to 60 microns is typically adequate. For heavier or bulkier items, or shipments passing through multiple automated sorting stages, 70 to 90 microns provides better puncture resistance and tear strength.
If your products have sharp corners, metal components, or anything that could puncture thin film from the inside, specify a higher micron count or consider a co-extruded film variant that combines layers with different properties. RB Plast’s technical team can test sample fills before confirming a specification.
The Business Case for Branded Courier Envelopes
Plain white or grey courier envelopes do the job. But branded courier envelopes do the job and market your business simultaneously. Every parcel passing through a courier depot, sitting in a post room, or being carried to a front door is a moment of brand exposure — not just to the recipient, but to everyone who handles it along the way.
Custom-printed polymailers with your logo, brand colors, and website URL transform a functional item into a marketing asset. The cost difference between plain and printed envelopes is often smaller than expected at production volumes typical for active e-commerce businesses, and consistently pays for itself through brand awareness and perceived product quality. RB Plast produces custom-printed courier envelopes with flexographic printing up to 2 colors, with in-house design support available.
Security Features and Tamper Evidence
Standard polymailers have a permanent adhesive seal that tears the film if someone attempts to open and reseal them — leaving visible evidence of tampering. For businesses shipping higher-value items, additional security measures can be incorporated: opaque film so contents cannot be seen, or a numbered seal that must be broken to access contents. Discuss your security requirements with RB Plast before finalising a specification.
Sustainability Considerations for Polymailers
Polyethylene courier envelopes are technically recyclable through soft plastics collection points, though collection infrastructure varies across Bulgaria and the wider region. Some manufacturers can produce polymailers incorporating a percentage of recycled content. RB Plast’s options for recycled-content packaging can be discussed with our sales team — contact us at sales@rbplast.bg.
Frequently Asked Questions
Q: What size polymailer do I need for clothing?
A: As a rule of thumb, the polymailer should be 5–8 cm wider and 10–15 cm taller than the folded garment. For a typical folded t-shirt, a 35×45 cm bag is a common starting point. For larger items like folded jackets, 45×55 cm is more appropriate.
Q: Can I order polymailers with my logo printed on them?
A: Yes. RB Plast produces custom-printed polymailers with flexographic printing in up to 2 colors. We offer design support for clients who need artwork developed. Contact sales@rbplast.bg to discuss minimum quantities and lead times.
Q: What is the difference between a polymailer and a courier envelope?
A: A polymailer is a fully flexible bag with a peel-and-seal closure, suitable for soft goods that can compress. A courier envelope typically includes a rigid backing (cardboard or foam) to protect flat items that must not be bent — documents, certificates, or rigid accessories.
Q: Are polymailers waterproof?
A: Yes. Polyethylene polymailers are inherently water-resistant. The seam and closure strip provide an effective barrier against rain and surface moisture during normal courier handling. They are not designed for submersion.
Contact RB Plast at sales@rbplast.bg or +359 887 648 950 for pricing, samples, and minimum order information.
