Royal Mail Small Parcel boxes: the cheapest on eBay

Max size: 45 × 35 × 16 cm, up to 2 kg. £4.60 2nd class, £5.90 1st class.

We searched 60 eBay sellers so you don't have to. Stop overpaying for packaging: here's the biggest box that fits a Royal Mail Small Parcel, at the best price for however many you need, delivery included.

The biggest box that fits: 440×340×145mm

17.3×13.4×5.7 inches · 21.7 litres · the most room you can get without going over

How many	Per box
Up to 25	£1.04 each25 boxes, £25.95 delivered	View on eBay
26 to 100	79.0p each100 boxes, £78.95 delivered	View on eBay
Over 100	72.0p each500 boxes, £359.95 delivered	View on eBay

Need something smaller for everyday orders? The 305×230×150mm box is 30.8p each, under half the price. It takes folded clothes, books and a few small items. See every pack.

Why not 450×350×160? That's usually the inside size, so the box ends up over the limit. More on that below.

Need a different size? We have every box that fits further down, plus all box sizes.

What fits in a 440×340×145mm box?

More than you'd think. It's roughly the size of a shoebox and a half. Things that fit, with room for some padding:

A pair of trainers in their box, up to about a UK size 11 (most shoeboxes are around 33 × 21 × 12 cm).
Clothes bundles: 2 or 3 folded hoodies or pairs of jeans, or 6 to 8 T-shirts.
A laptop up to 15 inches, wrapped in bubble wrap.
Vinyl records: up to about 8 LPs (they're 31.5 cm square, and 8 is roughly the 2 kg limit).
Board games like Monopoly (about 40 × 27 × 5 cm).
Books, games, DVDs and toys, as long as you watch the weight.

What won't work: anything deeper than 14.5 cm once it's in the box (most toasters, boots or a stack of plates), and anything over 2 kg. Books and paper get heavy fast: a single ream of A4 weighs about 2.5 kg, so it's already over.

Good for: clothing sellers posting bundles, trainer and shoe resellers, record and game sellers, and anyone who wants one box size that covers most orders.

Real prices. Every price includes delivery and is checked against its own eBay listing.
Safely under the limit. Every box here is at least 6mm under the Small Parcel size on every side.
Buy direct. We don't sell anything. Tap a price and buy from the seller on eBay.

Compare all box sizes and packs →

Prices checked 20 October 2026. These are Royal Mail's published limits.

Quick answers

What size is a Royal Mail small parcel?

The maximum dimensions are 45 × 35 × 16 cm (about 18 × 14 × 6 inches). It's measured once packed, so tape and any bulge count.

How heavy can it be?

Up to 2 kg, box and packing included. Any heavier and it's a Medium Parcel.

How much does it cost to send?

£4.60 2nd class or £5.90 1st class with a stamp. Buy the label online and it's £4.40 and £5.70. Prices from 5 October 2026.

Will a 450×350×160 box fit?

Usually not. That's normally the size inside the box. Add the cardboard and it's a few millimetres too big, so Royal Mail can charge you for a Medium Parcel.

What other box sizes fit?

58 box sizes fit safely. Here are the 8 biggest, with the cheapest price for each:

Size (mm)	Cheapest each	Pack of 25 or fewer
440×340×14517.3×13.4×5.7 in · 21.7 litres	72.0p each500 boxes, £359.95 deliveredSingle wall box	£1.04 each25 boxes, £25.95 delivered
430×330×15016.9×13.0×5.9 in · 21.3 litres	82.1p each500 boxes, £410.65 deliveredSingle wall die-cut	£1.07 each25 boxes, £26.79 delivered
430×255×14016.9×10.0×5.5 in · 15.4 litres	63.5p each200 boxes, £127.00 deliveredSingle wall box	94.8p each25 boxes, £23.70 delivered
430×255×12516.9×10.0×4.9 in · 13.7 litres	52.1p each200 boxes, £104.20 deliveredSingle wall box	89.0p each25 boxes, £22.25 delivered
380×280×12515.0×11.0×4.9 in · 13.3 litres	75.6p each200 boxes, £151.15 deliveredSingle wall die-cut	£1.19 each25 boxes, £29.65 delivered
340×240×14513.4×9.4×5.7 in · 11.8 litres	44.8p each100 boxes, £44.79 deliveredSingle wall box	75.6p each25 boxes, £18.90 delivered
305×230×15012.0×9.1×5.9 in · 10.5 litres	30.8p each500 boxes, £154.00 deliveredSingle wall box	40.0p each25 boxes, £9.99 delivered
420×340×7016.5×13.4×2.8 in · 10.0 litres	86.0p each50 boxes, £43.00 deliveredSingle wall box	£1.15 each25 boxes, £28.73 delivered

Delivery included. Tap a price to see every pack and the eBay listing.

Can I use a padded bag instead?

Yes. If it's under 35.3 × 25 cm and 2.5 cm thick when packed, and weighs no more than 750g, it goes as a Large Letter, which is much cheaper. That's sizes A/000 to G/4. Bigger bags go as a Small Parcel. The cheapest:

Bag	Cheapest each	Pack of 25 or fewer
Size H/5270×360mm	17.0p each1000 bags, £169.99 delivered	35.2p each25 bags, £8.80 delivered
Size J/6300×405mm	23.4p each500 bags, £116.99 delivered	43.5p each20 bags, £8.70 delivered

Size K/7 is right on the limit, so once full it may measure over.