How big and how heavy can your parcel be? The limits your box will encounter
,
by Verpakkingdeals.nl
6 min reading time
Carriers work with fixed limits for length, width, height, and weight. Here's how to read those limits and choose your box sizes accordingly — including the 3.2 centimeters that trip up most packages.
You find a box that perfectly fits your product, tape it shut, and at the drop-off point, it turns out to be just too large for the shipping rate you were counting on. Or worse: it no longer fits through the letterbox and has to be sent as a parcel, while your customer paid the letterbox rate. This difference is usually in millimeters, not centimeters.
Carriers use fixed limits for length, width, height, and weight. Those who know these limits choose their box sizes accordingly—and not the other way around. Below are the limits specified by PostNL, and what they mean in practice for the boxes you purchase.
The Limits at a Glance
On its customer service page regarding dimensions and weight, PostNL lists the following maximums for domestic shipments (consulted August 2026):
Type
Maximum dimensions
Maximum weight
Letterbox parcel
38 × 26.5 × 3.2 cm
2 kg
Small parcel
38 × 28 × 15 cm
3 kg
Medium parcel
100 × 50 × 50 cm
10 kg
Large parcel
176 × 78 × 58 cm
23 kg
Other carriers use their own limits. If you ship via DHL, DPD, or a shipping platform, check those maximums on their own sites before committing to a box size for the coming months. Rates and conditions also change more often than box sizes, so recheck them if you order a large batch.
3.2 centimeters: The Limit You Most Often Encounter
The 3.2 cm letterbox limit is the strictest and most challenging, because a box that is theoretically 3 cm high becomes thicker in practice. Tape doesn't add anything, but a bulging flap, a folded packing slip, or a product that fills up just a bit too high does. That's why letterbox boxes are deliberately made lower than the limit allows.
If you go over 3.2 cm, you enter the parcel categories. The small parcel goes up to 38 × 28 × 15 cm and 3 kg. A cube of 15 × 15 × 15 cm fits exactly within that height: the white cardboard shipping box of 15 × 15 × 15 cm costs €1.99 and is exactly on the limit. Close that box neatly with the H-method, because a flap protruding 3 millimeters can push your shipment into another category.
Above that begins the medium parcel: up to 100 × 50 × 50 cm and 10 kg. Much more fits in there than people think. The moving box of 480 × 430 × 330 mm (50 liters, €3.50) remains well within those dimensions at 48 × 43 × 33 cm — but is more likely to hit the weight limit than the size limit. Filled with books, you can easily exceed 10 kg.
Weight: The Limit You Control
With dimensions, you are bound by your product. With weight, you have more choice, because a significant part of the weight is packaging. Paper and heavy cardboard count, as does filling.
Weigh one completely packed, representative shipment — including tape, filling, and packing slip. Use that figure from now on, not just the weight of the product.
Choose light filling if you are close to a limit. A roll of bubble wrap of 500 mm × 500 m (€12.95) protects without adding much weight.
Are you sending something fragile and flat? A bubble envelope of 33 × 23 cm (€0.80) weighs less than a box with loose foil inside.
If you are consistently just above a limit, it's better to split into two shipments than to pay for a higher category every time.
Different Numbers Apply for International Shipments
For international shipments, PostNL states stricter limits on the same page: a letterbox parcel may weigh 1 kg with dimensions of 38 × 26 × 3.2 cm. For a small parcel, calculations are not based on length-width-height but on the longest side (maximum 60 cm) and the total circumference of length plus width plus height (maximum 90 cm), with a weight up to 2 kg. For the medium parcel, it's 100 × 50 × 50 cm, with 23 kg within the EU and 20 kg outside.
That circumference rule is the pitfall. A box of 40 × 30 × 25 cm stays under the 60 cm longest side but comes to 95 cm circumference, thus falling outside the small parcel category. Calculate that sum before you pack, not after.
How to Translate This to Your Own Box Sizes
Measure your three best-selling products, including the protection they need. Find two or three box sizes that comfortably stay below a limit, rather than right up against it. Then, pack one box of each size completely as you would ship it, measure it with a ruler along the bulkiest side, and weigh it. What comes out of that is your true size.
All box sizes, envelopes, and filling can be found at Packaging & Shipping, letterbox sizes are grouped under Letterbox Packaging, and individual box types under Boxes. If you are sending larger items, check Moving Boxes. If you're unsure which size suits your product, or want to know the cost per parcel for a bundle of 100 pieces, email your dimensions to info@verpakkingdeals.nl and we'll help you calculate.
Choosing a USB hub for working from home: 2.0 or 3.0, how many ports, and with switches
· 3 min reading time
Choosing a USB hub for working from home: 2.0 or 3.0, how many ports and with switchesYour desk needs three USB devices, but your laptop only has two ports. Or...
Power outages in autumn: emergency supplies you'll actually use
· 2 min reading time
Autumn Power Outages: Emergency Supplies You'll Actually Use October to December. Heating isn't in full swing yet, but the nights are getting long and cold. If a power outage strikes...
Choosing a power bank: capacity, charging speed, and weight compared
· 2 min reading time
Choosing a Power Bank: Capacity, Charging Speed, and Weight Compared Your phone dies when you're out and about. The classic emergency solution is a power bank. But what capacity do...
