How to use the Artwork Shipping Box Calculator
- Pick units and the kind of artwork. Switch between inches · lb and cm · kg, then choose framed with glass, framed with acrylic, stretched canvas, flat work on paper, or a rolled print or canvas. Each choice fills in a typical depth and a sensible packing method.
- Enter the size and weight of the artwork itself — the frame or stretcher included, the box not.
- Set the packing. Choose corner protectors in one box, a foam-board sandwich, or a double box, and adjust the padding on each side. For rolled work, set which side becomes the tube length, the roll diameter and the space left at each end.
- Read the results. The diagram and stat cards give the box (or boxes) to buy, the packed weight, and the weight you will actually be billed for. The table repeats the calculation for each common divisor, and the line above it checks the parcel against carrier size limits.
- Pack and record. Tick through the Packing checklist, use Copy box sizes for your notes or a quote request, and share the page link to keep every setting.
Why carriers charge for the box, not the art
A framed 16 × 20 inch drawing might weigh 7 lb, yet it ships in a box the size of a small suitcase. Carriers price by the space a parcel takes up in the truck as well as its weight, using dimensional weight: length × width × height divided by a number called the divisor. You pay for whichever is higher, the scale weight or the dimensional weight.
Two details make the number bigger than people expect. First, each measurement is rounded up to the next whole inch before multiplying, so a box 7¼ inches deep counts as 8. UPS and FedEx do this, and USPS adopted the same rule on July 12, 2026. Second, the divisor has been shrinking. UPS and FedEx daily rates use 139; UPS retail counter rates use 166. USPS changed from 166 to 139 on the same July date, but still applies dimensional weight only to parcels larger than one cubic foot (1,728 cubic inches). Express services quoted in metric usually divide cubic centimeters by 5,000 to get kilograms — which works out at almost exactly the same as 139 in³/lb, while 6,000 cm³/kg matches 166.
Divisors on negotiated accounts and shipping platforms can differ, which is why the table carries a “check your carrier” badge and lets you type your own.
The same painting, three ways to pack it
The default example is a 16 × 20 × 1¼ inch framed piece with glass, 7 lb on its own. Here is what the packing choice does to the bill at the 139 divisor:
| Packing | Outer box, rounded up | Volume | Billable weight |
|---|---|---|---|
| One box, 2 in padding all round | 20 × 24 × 6 in | 2,880 in³ | 21 lb |
| Double box, 1 in inside, 1½ in outside | 21 × 25 × 7 in | 3,675 in³ | 27 lb |
| Double box, 1 in inside, 2 in outside | 22 × 26 × 8 in | 4,576 in³ | 33 lb |
The double box is the safer choice for glass, and the extra 12 lb is the price of that safety. Watch the depth, though: the third box is 7¼ inches deep before rounding. Trim a quarter inch off the padding and it becomes 22 × 26 × 7 in, or 4,004 in³ — 29 lb instead of 33, for the same protection everywhere except one face.
Size limits are measured with length plus girth: the longest side plus twice each of the other two. That third box comes to 26 + 2 × (22 + 8) = 86 inches, well inside USPS’s 108-inch limit for Priority Mail. A 24 × 36 inch canvas in a single box lands on exactly 108 inches, right at that limit; any bigger and USPS Ground Advantage, which accepts up to 130 inches, is the only USPS option left.
When a tube beats a box
Unframed prints and unstretched canvases travel far cheaper rolled. A 24 × 36 inch print rolled along its short side needs a tube about 28 inches long; at a 3-inch diameter that is only 252 cubic inches, under the one-cubic-foot threshold, so USPS charges its actual weight. The calculator also shows how many turns the roll makes — about 3.8 here — which tells you whether the core is too thin. Canvas needs a fatter roll than paper, and it goes paint side out so the paint is stretched rather than squeezed when it is laid flat again.
Tips from practice
Measure the packed box, not the plan. Bulging tape and corner protectors add a little to every side, and any fraction rounds up. Measure the sealed box at its widest points before buying the label.
Order boxes before you finish the frame. A stock box that fits beats a custom one built from scraps, which is always bigger and heavier than it needs to be. Plan the frame with the Frame & Mat Size Calculator and you can order boxes at the same time.
Put the shipping cost on the invoice as its own line. Buyers accept a clear, itemized charge more easily than a price that quietly went up; the Art Invoice Generator has a shipping preset for exactly this.
Insure for replacement value and keep proof of it. A previous sale, an invoice or a price list showing what the piece sells for makes any claim far easier to settle.
Ship glass only when you must. Acrylic glazing weighs about half as much, doesn’t shatter, and turns the most stressful part of the checklist into a non-issue.