Skip to content
BilledWeight

18x18x12 box dimensional weight

3,888 cubic inches (2.25 cu ft, 0.0637 m³). Often used for bedding, bulky soft goods.

Billable weight floor by carrier

Packed lighter than this, you are billed this weight anyway.

CarrierDivisorDIM weight
USPS13928 lb
UPS (Daily Rates)13928 lb
FedEx13928 lb
UPS (Retail Rates)16624 lb
DHL Express (International)500013 kg

Stepping down to a 24 × 12 × 12 in box drops the UPS and FedEx floor to 25 lb, 3 lb less per parcel.

This box is over 1 cubic foot, so USPS applies dimensional weight.

Try it with your packed weight

Enter your box

L 18W 18H 12

Your box Rounded up by USPSWhole numbers, nothing rounded

Sample box shown. Type your own size and weight below; the result updates instantly.

Carrier
Try:

Your resultlive

USPS · divisor 139

Priority Mail, Priority Mail Express, Ground Advantage, Parcel Select

Billed on dimensions

Billable weight

28lb

You pay for 17 lb of air on every box.

Billed sides
18 × 18 × 12 in
Volume ÷ 139
3,888 → 27.97

A box 1 inch smaller on every side bills 5 lb less.

Same box, other carriers
USPS÷13928 lb
UPS÷13928 lb
FedEx÷13928 lb
UPS Retail÷16624 lb
DHL Express÷500013 kg

18x18x12 box questions

What is the dimensional weight of a 18x18x12 box?

3,888 cubic inches ÷ 139 = 27.97, rounded up to 28 lb for UPS Daily Rates and FedEx. USPS also bills 28 lb since the July 2026 change.

How heavy does a 18x18x12 box need to be to avoid DIM charges?

With UPS and FedEx, anything packed under 28 lb is billed as 28 lb. Above that, you pay actual weight.

Carrier rules verified 2026-09-30. Methodology