Bubble mailers explained: how to choose the right size and type for your shipments
Bubble mailers sit in a useful middle ground between poly mailers and cardboard boxes. They weigh almost nothing, cost less than a box, and provide enough cushioning to protect small items from the knocks they’ll take on a sorting belt. But with dozens of variants available – different sizes, liner types, materials and closures – choosing the wrong one can mean damaged goods, failed carrier scans, or unnecessary spend on packaging that’s heavier or larger than the shipment actually needs.
What is a bubble mailer?
A bubble mailer is a padded mailing envelope with an outer layer of polyethylene film and an inner lining of bubble wrap. The combination is lightweight, waterproof, and resistant to the mechanical stress of automated sorting. Most come with a self-seal peel-and-stick closure and a white label panel on the outside for printed shipping labels.
The key difference from a standard poly mailer is the cushioning. A flat poly bag offers no protection against impact; a bubble mailer absorbs light shocks along all surfaces. It’s not a substitute for full foam packaging, but it does the job for anything that can withstand moderate pressure without breaking.
When to use bubble mailers – and when not to
Good fit: jewellery, small electronics, phone accessories, cosmetics, books, CDs, DVDs, flat clothing items, printed materials, greeting cards. Anything fragile enough to need protection but not so delicate that it requires immobilisation inside a rigid box.
Poor fit: products heavier than 1.5–2 kg where the bubble lining adds weight without adding proportionate protection; items with sharp protrusions that risk puncturing the liner; or products that need to arrive in presentation-ready condition, since bubble mailers can crease flexible contents along the envelope edges.
Types of bubble mailers
Classic poly bubble mailers are the default for most e-commerce operations. The outer LDPE film is tear-resistant and waterproof; the bubble lining is bonded to the inside. Available in sizes from small (C/0 – roughly 115 × 195 mm) up to large (K/7 – 370 × 480 mm). Suitable for Royal Mail, DPD, Evri, DHL and most UK carriers.
Eco bubble mailers use either a recycled content (PCR) outer film, a kraft paper outer with a bubble liner, or both. The paper variant is popular with brands that want sustainable-looking packaging; it’s slightly heavier and more moisture-sensitive than the plastic version. PCR poly bubble mailers are functionally identical to standard ones but made with post-consumer recycled content – relevant for retailers complying with EPR (Extended Producer Responsibility) requirements in the UK.
Printed bubble mailers have flexographic print applied to the outer film – logo, brand colours, return instructions. Minimum order quantities at manufacturers typically start at a few thousand units. For smaller volumes, plain mailers with an insert card are more cost-effective.
For businesses sourcing in larger volumes, Filmar Group produces a range of bubble mailer envelopes supplier options – classic and eco variants – manufactured in the EU with documentation available for carrier compliance checks.
Sizes: how to pick the right one
Bubble mailer sizing codes (C/0, D/1, E/2 etc.) are not standardised across suppliers – a “D” at one company may differ from a “D” at another. Always select on actual dimensions, not letter codes.
The rule of thumb: the mailer should fit the product with 2–3 cm clearance on each side so the bubble lining can do its job at the corners. Too large and contents shift; too small and you’re compressing the bubble layer flat.
Typical sizes: small (approx. 120 × 215 mm) for jewellery and SIM cards; medium (approx. 180 × 260 mm) for phones and paperbacks; large (approx. 250 × 350 mm) for tablets and hardbacks; XL (300 × 440 mm+) for A4 documents.
What to check when buying in bulk
Outer film thickness – 60–80 µm is standard for most e-commerce. For international shipments or parcels going through multiple sortation stages, 90–100 µm is more robust.
Bubble diameter – small bubbles (around 3 mm) conform better to irregular shapes; larger bubbles (10 mm) offer more cushioning depth for heavier items.
Seal strength at low temperatures – sortation centres run overnight in cold conditions. Cheaper adhesives lose tack below 5–8°C, which means parcels arrive open. Ask suppliers for cold-temperature adhesion data on the closure strip.
Carrier compatibility – Royal Mail, DPD, DHL and Evri each have their own dimensional and weight limits. Verify that the mailer you’re ordering has been tested or approved for the carriers you use, particularly if you’re using automated label application.
For most small-item e-commerce shipments, a poly bubble mailer in the right size is the most cost-efficient protective packaging available. The choice between classic and eco variants depends on your EPR obligations and brand positioning. When ordering in volume, prioritise consistent film quality, reliable seal performance in cold conditions, and carrier documentation over headline unit cost.
