By Nicolas Avila · October 10, 2026

Measuring packaging: products that cost more to ship than they need to

Photo: Avila Ops Tecnologia

A box larger than the product needs raises shipping costs without benefiting anyone. Carriers charge by dimensional weight when it exceeds actual weight (Correios only does so when dimensional weight exceeds 5 kg), and dimensional weight comes from the box’s volume. A 600 g cushion in a 40 x 40 x 40 cm box is charged as 10.7 kg by Correios; in a 40 x 40 x 15 cm box, it is charged by actual weight. The fix is to measure, standardize three box sizes, and enter the correct dimensions in your store.

Packaging seems like a small cost, but it repeats with every order. The wrong box adds a few reais to each shipment; over 200 monthly shipments, that amounts to an entire monthly subscription. And the damage starts before the sale: the website already shows inflated shipping, and the customer leaves without you knowing why.

What is dimensional weight, and why does it matter?

Carriers sell truck space, not just weight. That is why they convert a box’s volume into kilograms:

Dimensional weight (kg) = length x width x height (cm) / factor

Correios uses a factor of 6,000. Private carriers use their own factors; check each carrier’s rate table. Charges use the greater of actual and dimensional weight when dimensional weight exceeds a threshold: 5 kg at Correios. Up to 5 kg of dimensional weight, Correios charges by actual weight. Other carriers may apply dimensional weight at any weight.

Two examples using the Correios rule:

In the wrong box, the same cushion incurs shipping for a product almost 18 times heavier. If the store lists the large box, that is the price customers see. The calculation mechanism is explained in shipping calculation by ZIP code.

How do you standardize boxes?

You do not need one box for every product. You need a few boxes that cover almost everything:

1. Set aside your 20 best-selling products and measure each with the minimum necessary packaging (product plus protection).
2. Group them into three sizes: small (an envelope or a box up to 20 cm), medium, and large. If most fall into one size, adjust the other two around it.
3. Buy boxes in those three dimensions. Packaging suppliers sell batches at a lower unit price than stationery stores.
4. List each product in the store with its assigned box dimensions, not the dimensions of the unpackaged product. That makes website shipping match the counter price.
5. For orders with more than one item, define a rule: up to two small items go in a medium box, and so on. Platforms that combine items automatically use these dimensions.

Correios has a maximum combined length, width, and height, along with minimum package dimensions; consult the current table before ordering boxes so you do not buy one the post office will reject.

Where else does packaging add unnecessary cost?

Besides size, three common sources of waste:

• Too much protection. Bubble wrap around a product that cannot break takes up space and adds weight. Crumpled kraft paper provides enough protection for clothing, stationery, and most objects.
• A box inside a box. A product already protected in its manufacturer’s box can go in a reinforced envelope or a layer of paper.
• An overly fancy box. Color-printed packaging costs several times more than a plain brown box with a brand label or stamp. Customers remember what was inside, not the box.

Packaging weight also counts. A heavy cardboard box adds 100 g or more; for a lightweight product, that changes the price bracket. Weigh the complete shipment, not the product alone, and enter that weight in the listing alongside each item’s code; see what is an SKU.

What to do now

Get a measuring tape and a kitchen scale. Measure and weigh your ten best-selling products already packaged, and compare with your store listings and the boxes you use today. Replace boxes that are larger than necessary. Correct any mismatched listing information. To move products, inventory, and shipping out of spreadsheets, with each item’s weight and dimensions, without losing your history: avilaops.com/sistema-para-pequenas-empresas or contact us on WhatsApp: wa.me/5517997811471.

Frequently asked questions

What is dimensional weight at Correios?

It is the box volume converted into kilograms: length x width x height in centimeters, divided by 6,000. It only counts when it exceeds 5 kg; charges then use whichever is greater, actual or dimensional weight. A large, lightweight box above that limit incurs heavy-product shipping rates.

What is the best packaging for shipping clothes?

A plastic or reinforced paper envelope, with the garment folded and a thin protective layer. It is lightweight, takes up little space, and qualifies for the lowest shipping bracket. Use boxes only for garments that wrinkle and cannot be ironed.

How many box sizes should I have?

Three cover most small stores: small, medium, and large, defined by your best-selling products. More than five becomes idle box inventory.