Guide to Accurately Measuring Your Parcel for Shipping (2026 Update)
Written by Valentin Scemama, Shipping Insurance Expert at Secursus.
The dimensions of your package are the #1 factor carriers use to calculate the price of your shipment. Whether you are looking for Post Office parcel measurements or shipping via a private courier, measurements must be exact to the nearest centimeter in 2026.
Crucial Rule: Always measure the outside dimensions of your parcel, never the inside. Packaging suppliers often list internal capacity, but carriers bill you for the external volume.
Measurement Matrix: Quick Reference
| Item Type | What to Measure | Key Advice |
|---|---|---|
| Standard Box | L x W x H | Measure the longest side as Length. |
| Cylinder / Tube | Length + Diameter | Diameter is used as both Width & Height. |
| Pallet (Euro) | 120 x 80 x Height | Include the pallet base in the height! |
| Irregular Shape | Imaginary Box | Measure the extreme points as if it were in a box. |
How to measure a parcel (Classic Cardboard Box)
If you are wondering how to measure a parcel correctly, follow this standard 3-step process. All three must be measured in centimeters.
- L (Length): The longest side of the parcel.
- W (Width): The intermediate side.
- H (Height): The shortest side.
Pro Tip: If your object is cylindrical (like a poster tube), carriers calculate the volume by squaring the diameter. Formula: Length x Diameter x Diameter.
Carrier Specifics: Royal Mail, Post Office & Evri
Different carriers have strict size buckets. Failing to meet small parcel measurements can double your shipping cost. Here is the 2026 breakdown for the UK market:
1. Royal Mail & Post Office Parcel Measurements
The Royal Mail small parcel measurements (often identical to general Post Office small parcel measurements) are the most searched criteria because they are very restrictive on height/depth.
- Small Parcel: Max 45cm x 35cm x 16cm (Max 2kg).
- Medium Parcel: Max 61cm x 46cm x 46cm (Max 20kg).
If your box is just 17cm high, it exceeds the Royal Mail small parcel measurements and you will be charged the "Medium" rate. Always check these parcel measurements for Royal Mail before heading to the counter.
2. Evri Parcel Measurements
Evri parcel measurements generally follow a "Total Girth" rule or simple weight bands, which can be more forgiving than the Post Office for slightly bulky items.
- Postable: Max 35cm x 25cm x 2.5cm (Fits through a letterbox).
- Standard: Max length 120cm + (2 x width) + (2 x height) must be less than 245cm.
How to measure a pallet for shipment?
For larger shipments, the logic remains the same, but you must include the wooden structure of the pallet in your vertical measurement.
- Standard Euro Pallet: 120 cm (Length) x 80 cm (Width).
- Measurement Rule: Measure from the floor (bottom of the wood) to the very top of your stacked goods.
Reference measurements (Common Objects)
To help you visualize, here are standard dimensions to compare with Post Office parcel measurements:
- Shoe box: ~ 35 cm x 22 cm x 13 cm (Fits easily in "Small Parcel").
- A4 Sheet of Paper: 21 cm x 29.7 cm.
- Postcard: ~ 16 cm x 11 cm.
The "Volumetric Weight" Trap: Don't get overcharged
This is where 90% of shippers make mistakes. Carriers do not just look at the Actual Weight (kg) on the scale; they also calculate the Volumetric Weight (density).
The Rule: The carrier will always bill you based on the higher of the two weights.
How is it calculated?
Most express carriers (DHL, FedEx, UPS) use this formula: Volumetric Weight (kg) = (Length x Width x Height in cm) / 5000
Example: You ship a large pillow (50x50x50cm, 1kg).
- Volumetric Calculation: (505050) / 5000 = 25 kg.
- Result: You pay for 25kg, not 1kg.
Always optimize your packaging size to reduce empty space and lower your shipping costs. And remember, whether your parcel is small and heavy or large and light, Secursus insures your shipment up to £90,000 against loss, theft, and damage.
