Buyers pay for shipping based on the weight and size you enter for each product. Enter the weight and size of the packed package, ready to ship, not the item on its own. This guide shows you how, including tubes, soft mailers, and products with options.

Why the box matters

Carriers charge by size as well as weight. A light item in a big box can cost far more to ship than its weight suggests.

Here is one example: the same 1 lb package, shipped from Minneapolis to Chicago, in a small box and in a big box.

These were live prices for one route on November 1, 2026. Prices change, but the gap between a small box and a big one is the point.

Getting your numbers right protects you both ways:

• Numbers too small: the label you buy can cost more than the buyer paid for shipping, and you cover the difference.
• Numbers too big: buyers see a higher shipping price than they need to pay, and some of them won't buy.

Before you start

• The box, tube, or mailer you'll actually ship in
• Your packing materials, like bubble wrap or paper
• A tape measure or ruler
• A scale that reads pounds and ounces, like a postal or kitchen scale

Step 1: Pack it the way you'll ship it

Put the item in its box with all the padding, inserts, and anything else that goes inside, like a care card or a thank-you note. Close it up. You'll measure and weigh this finished package, not the item.

If you sometimes pack the same product in different boxes, use the bigger one.

Step 2: Measure the outside of the package

1. Length: the longest side.
2. Width: the next longest side.
3. Height: the shortest side.

Always put the longest side in Length. BlackSpace doesn't reorder them for you.

Measure the outside edges, not the inside, and round each one up to the next whole inch. A side that measures 7 1/4 inches is 8.

Step 3: Weigh the packed package

Put the whole closed package on the scale and note the weight in pounds.

• Under a pound: type it as a decimal. Divide the ounces by 16. For example, 8 oz is 0.5 and 12 oz is 0.75.
• Pounds and ounces: do the same with the ounces. For example, 2 lb 4 oz is 2.25.

If you're between two numbers, use the higher one.

Odd shapes

Every product gets the same three measurements: length, width, and height. For anything that isn't a box, picture the smallest box it would fit in, and measure that.

Tubes

Rolled prints, posters, and maps often ship in a mailing tube.

• Length: end to end, including the caps.
• Width and Height: the distance across the tube at its widest point. Enter that same number in both boxes.

Soft mailers and padded envelopes

Measure the mailer after the item is inside and it's sealed.

• Length and Width: lay it flat and measure the two sides.
• Height: the thickest point. A filled mailer is never 0 inches tall.

Anything else

For a round, curved, or lumpy package, measure the longest distance in each direction, as if you were drawing a box around it.

Step 4: Enter the numbers

For a simple product

Open the product in your Seller Dashboard and scroll to the Shipping card. Type your numbers into Weight (lbs) (1), Length (in) (2), Width (in) (3), and Height (in) (4). Type the numbers only, without "lbs" or "in." Then save the product.

For a product with options

If buyers choose a size, color, or other option, fill in the product's main Shipping card first, using the packed package for your most common option.

Then, for any option that ships in a different box or weighs more, open that option's variation and fill in its own Weight (lbs), Length (in), Width (in), and Height (in) (1). Click Save Variation (2) before you move to the next one.

Leave a variation's box blank to use the number from the main Shipping card. Each box works on its own, so you can fill in just the weight and leave the size boxes blank. Never type 0 in any of these boxes.

For step-by-step help with options, see How to list a variable product.

When a buyer orders more than one

When a buyer orders two or more items from your store, BlackSpace quotes them as one package. It adds up the weights and works out one box that fits all the items, with some extra room for packing.

That makes the shipping price for those orders an estimate. Pack the items as snugly as you safely can, and use one box when you can.

When the numbers are required

BlackSpace won't publish a product you ship until it has a weight and all three measurements. For a product with options, that can be on the main Shipping card or in every variation.

The one exception is a product you only deliver yourself. Check Local delivery only in its Shipping card, and it doesn't need a weight or measurements. See How to set up your shipping to turn on Local Delivery first.

If a product you ship is missing its numbers anyway, BlackSpace can't get a shipping price for it. A buyer who wants it shipped sees "No shipping options were found" in their cart, and checkout offers no way to ship it.

A quick check before you publish

• You measured the packed package, not the item.
• Every side is rounded up to a whole inch.
• The weight includes the box and the padding.
• A tube has the same number in Width and Height.
• Each option that ships differently has its own numbers.

To set where you ship from, your handling fee, free shipping, and local pickup, see How to set up your shipping.