About DimMath

Nobody talks about the moment a shipment costs more than you expected.

You priced the product. You calculated the fees. You hit ship. Then the charge came through and the margin you planned for was gone. Not because you made a bad decision. Because the number you used was wrong before you even started.

DIM weight charges catch part-time sellers the most. You ship a light item in a big box and the carrier bills you for the volumetric weight, not the actual weight. The difference can double your shipping cost on a single order. Most sellers find out after the fact.

FBA sellers run into the same wall differently. The product looks profitable on paper. Then referral fees, fulfillment fees, inbound shipping, and COGS stack up and the margin disappears. There is no free tool that puts all of that in one place and just tells you: GO or NO-GO before you order inventory.

DimMath was built to close that gap.

Enter your dimensions and weight. See all four carriers side by side: UPS Ground, FedEx Ground, USPS Ground Advantage, USPS Cubic. Cheapest option highlighted. If a rate applies to your package, you see it. If it doesn't and why, you see that too.

Every rate is verified against official carrier fee schedules on a fixed schedule. There is a public changelog so you know exactly when data was last confirmed. Nothing is hardcoded and left to go stale.

No login. No subscription. Just the answer before the box is sealed.

Operational Integrity

DimMath uses a versioned rate database updated on a fixed schedule. Every change is logged publicly in the Changelog. Stale data is flagged automatically.

Disclaimers

Rates are retail estimates and may not reflect negotiated discounts or peak surcharges. DimMath is not affiliated with UPS, FedEx, USPS, DHL, or Amazon.