We pack an exercise bike, measure the box, and get 149 cm in length. The package passes, and we think we are in the clear. Except that the handlebars stick out of the packaging by a few centimeters, and at the depot, the agent refuses the package. The issue of large parcel dimensions with Colissimo cannot be resolved with a simple tape measure placed on the box: it is essential to understand what La Poste actually measures and when it crosses into oversized territory.
Measuring a Colissimo package: the actual size, not the theoretical box
La Poste does not measure your empty packaging. It measures the package as it appears at the depot, including protruding parts and thicknesses. A cardboard tube with a cap that sticks out, a box bulging from the contents, adhesive tape creating a bump on the edge: all of this is included in the calculation.
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Specifically, we take the length (L), width (l), and height (h) of the package in its most cumbersome position. These three measurements are then used to verify two things: the maximum length of the longest side and the sum L + l + h.
To clearly understand the large parcel dimensions with Colissimo, it is important to note that La Poste applies the rule to the closed package ready for shipping, not to the flat box. If your item distorts the packaging or creates a protrusion, it is the maximum external measurement that counts.
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Colissimo size thresholds in 2026: standard, large, and refused
La Poste’s grid distinguishes three cases based on the size of the package. Here, we are not talking about weight (limited to 30 kg), but solely about dimensions.
Standard package
A package falls into the standard category when the sum L + l + h does not exceed 150 cm and no side exceeds 100 cm. No extra charge, base rate according to weight.
Large package with surcharge
When the sum L + l + h exceeds 150 cm but remains within the limits accepted by the network, La Poste applies a surcharge of 6 euros. This additional cost is added to the normal postage. We move into this category as soon as a single centimeter crosses the threshold.
Oversized package, not accepted
Beyond a certain point, Colissimo simply refuses the package. A package refused at the depot has no alternative in the standard postal network. You must turn to a private carrier or a service dedicated to bulky items.
Returns vary on this point depending on the post offices: some agents measure to the nearest centimeter, while others allow a slight excess. You cannot rely on this tolerance.
Rolls and cylindrical packages: a specific Colissimo rule
Long and thin objects (poster tubes, posters, rods) pose a particular problem. A roll of 120 cm long with a diameter of 15 cm has a sum L + l + h that is very different from a cube box of the same apparent proportions.
La Poste provides specific handling for rolls. The calculation formula remains the same (adding the three dimensions), but the diameter of the roll is measured twice as it replaces both the width and the height. A tube that is 110 cm long and 15 cm in diameter thus gives: 110 + 15 + 15 = 140 cm, which remains below the standard threshold.
Where we get caught is with end protections. A foam cap of a few centimeters on each side can push a roll into the large package category.
When the size exceeds: options outside Colissimo
A flat-pack furniture item, a bicycle frame, a surfboard: these items almost always exceed Colissimo limits. The distinction between “large package” and “oversized package” is an operational boundary that directs towards different delivery circuits.
- Messenger carriers (like Mondial Relay, private carriers) generally accept larger packages, with thresholds varying by provider and destination.
- Bulky item transport services offer home pickups for items that do not fit into any standard postal network.
- Some e-commerce brands negotiate specific contracts with La Poste for non-standard formats, but these agreements are not accessible to individuals.
Before choosing a shipping method, measure the packaged item, taped, with all its protections, and then apply the formula L + l + h. Not the other way around.
Common mistakes regarding Colissimo dimensions
Most refusals at the counter come from three recurring situations.
- Measuring the empty box before placing the item inside: the contents often distort the packaging and add several centimeters to each dimension.
- Ignoring straps, handles, or flaps that protrude: any element outside the basic rectangular prism is included in the calculation.
- Confusing the maximum length of one side with the total sum: a package can have one side of 90 cm (below the threshold) but a sum L + l + h that exceeds 150 cm due to the combined width and height.
The most reliable reflex remains to measure the closed package in its final configuration, then check the two criteria (length of the longest side and sum of the three dimensions) before going to the post office. A package refused after a car trip is wasted time for everyone.