How do you calculate dimensional weight?

Multiply length × width × height in inches, then divide by the carrier's DIM divisor: 139 for FedEx and UPS, 166 for USPS Priority. The result is the dimensional weight in pounds. The carrier bills whichever is greater — actual weight or dimensional weight. Try it above with your own box dimensions.

What is the DIM divisor for FedEx and UPS?

Both FedEx and UPS use a DIM divisor of 139 for domestic shipments (inches and pounds). USPS Priority Mail uses 166. A smaller divisor produces a larger DIM weight, which is why bulky boxes get expensive fast. This tool applies the right divisor automatically when you pick a carrier.

What is billable weight in shipping?

Billable weight is the weight your carrier actually charges on: the greater of your package's scale (actual) weight and its dimensional weight, rounded up to the next whole pound. If your box is light but large, DIM weight wins and you pay for size, not weight.

Why is my shipping cost higher than the package weight suggests?

Almost always dimensional weight. Carriers price the space your box takes on the truck, not just its scale weight. A 4 lb box measuring 24×18×18 bills at 56 lbs on FedEx. Repack into a smaller box and the DIM weight — and your cost — drops immediately.

Is this shipping cost estimator accurate?

It accurately computes dimensional and billable weight, which is the part of pricing most sellers get wrong. But it is an estimate, not a rate quote: real prices also depend on shipping zones, service speed, fuel surcharges, and accessorial fees. Use it to sanity-check quotes, then confirm in the carrier's official rate tool.

How can I lower dimensional weight charges?

Use the smallest box that safely fits the item, since DIM weight is pure volume math. Consider poly mailers for soft goods (they often dodge DIM pricing), and compare carriers — USPS Priority's 166 divisor is friendlier to bulky boxes than the 139 used by FedEx and UPS.

Shipping Cost Estimator

What is Shipping cost estimator?

Shipping Cost Estimator — Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.

Dimensional weight is computed as (length × width × height) ÷ the carrier's DIM divisor: 139 for FedEx and UPS, 166 for USPS Priority Mail. Billable weight is the greater of actual weight and dimensional weight, rounded up to the next whole pound, which matches how these carriers bill. This is an ESTIMATE: it does not include zone pricing, fuel surcharges, residential or oversize fees, and carrier divisors can change — always confirm with the carrier's own rate tool before quoting a customer.

Why use this shipping cost estimator?

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Built for shipping cost estimator

Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.

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Transparent & honest

DIM divisors used: FedEx 139, UPS 139, USPS Priority Mail 166 (domestic, inches/pounds). Carriers can change divisors — verify before quoting customers.

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Private by design

Everything runs in your browser. Your inputs never leave your device.

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Works everywhere

Fully responsive — perfect on desktop, tablet, and mobile. No app needed.

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Regularly updated

Regularly maintained and reviewed to ensure accuracy.

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Free forever

No accounts, no limits, no watermarks. Use Shipping Cost Estimator as much as you need.

How to use Shipping Cost Estimator

1Enter your package's actual weight in pounds and its length, width, and height in inches.
2Pick your carrier — FedEx, UPS, or USPS Priority — and run the tool.
3Read the dimensional (DIM) weight next to your actual weight to see which one is larger.
4The billable weight is the larger of the two, rounded up — that is what the carrier charges on.
5Remember this is a weight estimate only: real rates also depend on zone, service level, and surcharges.

What can you do with Shipping Cost Estimator?

Dimensional weight calculator — Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.
Dim weight calculator — Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.
Billable weight calculator — Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.
How to calculate dimensional weight — Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.
Fedex dim weight divisor — Free shipping cost estimator — calculates dimensional (DIM) weight vs actual weight for FedEx, UPS, and USPS, and shows which weight your carrier will bill you for.

Good to know

DIM divisors used: FedEx 139, UPS 139, USPS Priority Mail 166 (domestic, inches/pounds). Carriers can change divisors — verify before quoting customers.
Billable weight is rounded UP to the next whole pound, matching standard carrier billing practice.
This is a weight estimate only — zone rates, fuel surcharges, residential/oversize fees, and service levels are not included, so it is not a price quote.

How it works

Dimensional weight is computed as (length × width × height) ÷ the carrier's DIM divisor: 139 for FedEx and UPS, 166 for USPS Priority Mail. Billable weight is the greater of actual weight and dimensional weight, rounded up to the next whole pound, which matches how these carriers bill. This is an ESTIMATE: it does not include zone pricing, fuel surcharges, residential or oversize fees, and carrier divisors can change — always confirm with the carrier's own rate tool before quoting a customer.

Examples

Light but bulky box via FedEx

DIM weight 55.97 lbs beats actual 4 lbs — billable weight is 56 lbs. The bulky box costs far more than its scale weight.

Dense small parcel via USPS

DIM weight 2.89 lbs loses to actual 6 lbs — billable weight is 6 lbs. Dense parcels bill on actual weight.

Medium box via UPS

DIM weight 21.73 lbs beats actual 9.5 lbs — billable weight is 22 lbs.

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