post office small parcel measurements

Post Office Small Parcel Dimensions

By Sarah BrownApril 21, 2026

When sending letters or packages through the post office, it's crucial to understand the size limitations, especially for small parcels. Proper measurement ensures efficient handling and avoids additional postage fees. Let's delve into the key measurements you need to be aware of for small parcels.

Post offices worldwide have standardized measurement systems to streamline their processes. This guide will focus on the measurements typically used in major postal systems like the United States Postal Service (USPS) and Royal Mail in the UK, which are common benchmarks for many countries.

Length, Width, and Height

The three primary dimensions to consider are length, width, and height. Standard sizing is crucial for easy sorting and storing in postal facilities. Most post offices consider a 'small parcel' to be anything below a specific length and/or volume.

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For instance, USPS categorizes packages under 108 inches in combined length and girth (the perimeter of the package) as 'Retail Ground' or 'Regional Rate.' In the UK, Royal Mail considers packages under 1.5 meters in length as small, with no upper limit for girth.

USPS Small Package Dimensions

For USPS, small parcels typically have the following measurements:

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Length: Up to 84 inches for both domestic and international packages.
Width: Up to 12 inches for domestic packages and 18 inches for international packages.
Height: Up to 18 inches for domestic packages and 108 inches for international packages, with the total combined length and girth not exceeding 108 inches.

Royal Mail Small Package Dimensions

For Royal Mail, small parcels usually fit within these measurements:

Maximum length: 1.5 meters (4.92 feet) for large letters and small parcels.
Maximum girth: No limit for small parcels, but they must fit through sorting and processing machines.
Maximum weight: Up to 20kg for small parcels.

Weight Considerations

While not a dimension, weight is another critical factor determining postage costs. Heavier items may require additional services or packaging to ensure safe transportation.

Most post offices have weight limits for small parcels, with USPS and Royal Mail setting the upper limit at 20kg or approximately 44 pounds.

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USPS Weight Limits

USPS uses the following weight categories for small parcel services:

First-Class Package Service: Up to 70 lbs.
Priority Mail Service: Up to 70 lbs.
Retail Ground/Regional Rate Service: Up to 70 lbs.

Royal Mail Weight Limits

Royal Mail's weight limits for small parcels are as follows:

Second Class Parcels weighing: Up to 2kg (small) and 10kg (medium/large).
First Class Parcels weighing: Up to 1kg (small) and 20kg (medium/large).

Understanding these measurements ensures your small parcels are correctly categorized and not subject to additional fees or delays. Always check the specific measurements and limitations with your chosen postal service for the most accurate and up-to-date information. Happy mailing!