Bubble wrap in a poly mailer for international post: when is it enough for small items?

A keychain is rarely fragile. So most of us send it overseas the same way we send it across India: one turn of bubble wrap and a poly mailer.

Most of the time it arrives perfectly fine.

When it does not, the customer's photo shows a bent charm, or a small hole where the split ring came through the film somewhere between two countries.

Here is my short answer. Bubble wrap in a poly mailer is enough for international post when the item is light and sturdy, cannot bend or crack, has no hard point that can push through, and is held still inside the mailer. If any one of those fails, add a stiff board or move the item into a small box. Then test the pack with a drop and squeeze check before you dispatch the next fifty orders.

At Jagannath Polymers we make cushioning and supply mailers from Jaipur, so we have an interest in the mailer answer. We will still tell you where a mailer is the wrong choice, because replacing an order abroad means paying international postage twice.

Why international post is harder on a small parcel

A domestic courier usually keeps your parcel from pickup to doorstep. An international postal item has at least two owners, the postal operator at each end, often with an airline in between.

I think of it as a direct train against a journey with two changes and a customs counter at each end. We pack our bags for the roughest handler on the way.

On that route a small packet meets three things a domestic parcel often does not:

1. Mailbags and machines. Australia Post's packaging guide (March 2026) says items are often handled in a mailbag or on automated equipment rather than individually. It asks for packing that survives machine sorting, drops of at least 1.2 m and pressure from heavier items.
2. Customs, possibly twice. The UPU Convention allows both the sending and the receiving post to submit items to customs control. The CN 22 form itself says "May be opened officially", so an officer may open your mailer and close it with less care than you took.
3. Time, temperature and air pressure. The same guide asks for packing that copes with extremes of heat and cold and with changes in air pressure during air carriage. A long route gives all of them more time to work on your parcel.

Then there is the money. India Post's International Tracked Packet Service page (last updated 19 October 2026) limits compensation for loss or damage to ₹1,000 or the actual value, whichever is less. Other operators set their own limits, so read yours.

For most small orders, the packing is the only real protection you have.

What the mailer and the bubble wrap each do

A poly mailer is a closed, tough cover designed for soft goods. Delhivery's packaging guidelines (updated 9 November 2024) recommend these flyers for flexible items such as clothes, in 60 to 80 micron LDPE.

Bubble wrap softens knocks and stops scratches. Our guide to bubble wrap grades covers bubble size, height and film.

What neither of them does is stop bending. A mailer bends with whatever is under it, and a thin item bends with the mailer. At the bottom of a sack, a soft pack also carries the weight of everything above it.

A hard point is the other weakness. A split ring, a metal corner or the end of a small tool can burst bubbles and then work its way through the film. Our own mailers are no exception, because film is film, whoever makes it.

Four questions that decide it

We suggest four questions about the item before you choose the pack. Ask them in this order, because the first yes decides the pack.

1. Can it crack or chip if dropped? Glass, ceramic, resin with thin parts and anything with a display all can. If yes, it needs a box.
2. Can it bend or snap? Thin acrylic charms, long thin metal parts and anything mounted on a card can. If yes, it needs a stiff board at least.
3. Does it have a hard point or edge? Split rings, clasps, keys and USB drives do. Australia Post's guide asks for rigid items like these to go in a rigid box or other packaging they cannot pierce.
4. Would losing it really hurt? For gold, silver, real stones or anything expensive, follow our guide to packing jewellery for courier. A mailer is the wrong pack there.

If the answer is no to all four, bubble wrap in a mailer is a sensible pack. Here is where I would start with typical small items:

How much bubble wrap does a small item need?

Less than most people think, and more than one loose turn.

A keychain that weighs a few grams hardly squashes the bubbles, so additional layers add little against the knock. For a small item, the wrap's real work is covering points, stopping scratches and giving the mailer a neat shape to hold still.

This is the starting set-up we suggest you test. Treat it as our suggestion, not a rule:

1. Use small bubbles. Large ones make a lumpy mailer.
2. Fold the split ring or clasp in against the body first, so the hard point sits inside the wrap.
3. Wrap two full turns and fold both ends over.
4. Close the wrap with one short piece of tape, its end folded back as a tab, so a customs officer can open it and close it again.
5. Wrap each item separately. Two items in one wrap rub against each other all the way.

We would not pay for barrier bubble for a light item. It matters when a heavy product rests on the bubbles for days, which our grades guide explains.

Stiffen it if it can bend

A poly mailer has no spine, so anything that can bend needs one.

Cut a piece of corrugated board or thick greyboard slightly smaller than the inside of the mailer. Lay the wrapped item on it and tape it down, so it cannot slide off. For thin acrylic, or anything else that snaps, use two boards, one on each side. The board also gives a split ring something firmer than film to press against.

This is why many of us carried our certificates to job interviews in a hardboard file. A crowded bus bends paper, and the file stopped it.

Then do the bend check. It is my favourite, because it catches the failure people usually forget.

Hold the packed mailer by both ends and flex it gently. If you feel the item flex, the board is too thin or too short.

Fill the space and stop it moving

Movement inside a mailer turns every knock into a hit, and lets the item work its way to a seam or a corner. Our guide on why products break in transit shows how this damage looks.

Choose the smallest mailer that takes the wrapped item and its board without forcing the seal. Do not go below the UPU minimum, though. A small packet's address side must be at least 105 x 148 mm, so for a very small item, let the board fill that size instead of air.

Press the seal strip down along its full width. For a long international route I would add one strip of tape across the flap as well.

Then shake the mailer next to your ear. Nothing should slide.

When to switch to a small box

Switch when the checks tell you to.

That means the item can crack, it still flexes with a board behind it, or a point shows through the film after the squeeze check. I would also box any order where several items could rub together, any retail box that must arrive unmarked, and any mailer that only closes when stretched over the item.

A box adds weight, and international postal rates usually go up in weight steps. I would weigh both packs and check the post office's rate card before deciding. If the box lands in the same weight step, the decision is easy.

For cushioning inside the box, our guide to choosing cushioning by product weight and fragility works at a small scale too.

The customs declaration: what the post office needs

Let us keep this part short, but please get it right. The UPU's own commentary blames delays to postal items on customs declarations that are unclear or incomplete.

1. Every small packet sent overseas carries a customs declaration. Under article 20-001 of the UPU rules and its commentary (in the Convention Manual, January 2025), that is a CN 22 when the contents are worth up to 300 SDR, and a CN 23 above that, or whenever you prefer it.
2. India Post lists 1 SDR at ₹115.2060 for 2026 on its International Speed Post page. That puts 300 SDR at about ₹34,560. Confirm the current figure at the counter.
3. Describe the contents in detail, because the UPU rules do not admit general descriptions. "Two metal keychains" works. "Accessories" does not.
4. For goods you have sold, the UPU rules in force from 1 June 2026 (International Bureau circular 86, 31 May 2024) ask for a six-digit HS code per article where the destination requires one. Your post office or the destination's customs website will tell you the code. I will not guess it here.
5. Both forms go on the outside, a CN 23 preferably in a transparent adhesive envelope, and you may attach an invoice with either. On a mailer, use the flat address side, away from the flap.

In India, you can generate a CN 22 and download a CN 23 from India Post's customs declaration page.

Remember the words "May be opened officially". I would also put a copy of the invoice inside the mailer, in case the outer one is torn off on the way.

The drop and squeeze check

This is the check I would run before changing any international pack. It needs a tape measure, a bare concrete floor and about twenty minutes.

1. Pack three mailers exactly as your packer will on an ordinary day.
2. Shake. Nothing should slide or rattle.
3. Bend. Flex each mailer gently by its ends. The item must not flex.
4. Squeeze. Lay each mailer flat and press hard with your thumb on the item's sharpest point and on each end. Nothing should poke through. For fragile items, Australia Post sets a stricter test: the item must not be felt through the wrapping.
5. Load. Leave each mailer overnight under a 5-litre can of water, or any weight you can repeat. This is my own stand-in for the bottom of a mailbag, not a standard.
6. Drop. From at least 1.2 m, the Australia Post minimum, drop each mailer flat on both faces, on all four edges and on one corner. That is seven drops. Our warehouse drop test explains how to drop fairly.
7. Open each one carefully and judge. No crack, chip, bend or scratch, no hole in the film, and the seal still closed.

Three mailers and five checks (shake, bend, squeeze, load and drop) give you fifteen results.

Anything short of fifteen passes means the pack changes. Add a board, cover the point better, take a smaller mailer or move to a box, then test three fresh mailers.

Last, post one real parcel. Most of us have a relative or a friend overseas. Send them one in the new pack and ask for a photo of the mailer before they open it.

After that, our guide to tracking your damage rate shows you how to watch real orders.

If you are unsure about a particular item, send us a photo, its weight and the country it is going to. We will suggest a pack you can put through this check.