Dimensional Weight Math Most Founders Ignore

Most founders have genuinely never run this math on their own product. Carriers bill dimensional weight, not just actual weight. The formula is length times width times height divided by 139, whichever is higher. Your product's real weight, or that calculation, is what you pay for. Work example: your product weighs 2 pounds. It ships in a box 12 by 10 by 8. 12 times 10 times 8 is 960 divided by 139 is just Under 7. So a 2-pound product billed as though it weighs almost 7. That's not a rounding error. It's more than 3 times the real weight on every single shipment you make. At volume, that's serious money, often 30 to 50% more than it needs to be on a best-selling SKU. And it never appears as a one-line item you could question. It's just baked into a freight bill that looks like shipping got more expensive, which is a sentence every founder has said at some point without investigating further.