12 × 9 × 3 box
volume & shipping weight
A 12 × 9 × 3 inch box holds 324 cubic inches — 0.188 cubic feet, or 5.31 liters. In metric it measures 30.5 × 22.9 × 7.6 cm.
What a 12x9x3 box bills at
Carriers charge the greater of actual weight and dimensional weight. For this box: 324 in³ ÷ 139 = 2.33 → 3 lb at FedEx, UPS Daily Rates and DHL; ÷ 166 = 1.95 → 2 lb at UPS Retail. If what’s inside weighs more than that, you pay the actual weight.
| Carrier / rates | Divisor | DIM weight | Billed at least | Note |
|---|---|---|---|---|
| FedEx (US) | 139 in³/lb | 3 lb | 3 lb | Fractions of an inch round up; weight rounds up to the next lb. |
| UPS Daily Rates | 139 in³/lb | 3 lb | 3 lb | Account rates. Dimensions round up to whole inches. |
| UPS Retail Rates | 166 in³/lb | 2 lb | 2 lb | UPS Store / counter, domestic. |
| USPS Priority Mail & Ground Advantage | 139 in³/lb | — | — | Not applied: 324 in³ is not over 1 ft³ (1,728 in³). Priced on actual weight. |
| DHL Express (from the US) | 139 in³/lb | 3 lb | 3 lb | Rated in whole-lb steps. |
| International, rated in kg | 5,000 cm³/kg | 2 kg | 2 kg | For rates quoted in kg (e.g. shipping from Europe or Asia): 31 × 23 × 8 cm after rounding each side up to the cm. From the US, FedEx and UPS use 139. |
“Billed at least” includes any minimum billable weight the box’s size triggers. Actual weight still wins if it’s higher.
Rules verified 22 Sep 2026 · sources: FedEx Service Guide 2026 · UPS 2026 Rate and Service Guide (Daily Rates) · UPS 2026 Rate and Service Guide (Retail Rates) · USPS DMM 223 (Priority Mail: DIM weight, cubic, nonstandard fees) · DHL Express US Service & Rate Guide 2026
Size checks for 12 × 9 × 3 in
Longest side 12 in, girth 2 × (9 + 3) = 24 in, so length + girth is 36 in. Here’s how that sits against each carrier’s lines (size only — weight rules are separate).
- UPS & FedEx Additional Handling (size)Clear. Longest side 12 in: 36 in under the 48 in line. Second-longest 9 in: 21 in under the 30 in line. Length + girth 36 in: 69 in under the 105 in line. Volume: 10,044 in³ under the 10,368 in³ line.
- UPS Large Package / FedEx OversizeClear. Length + girth 36 in: 94 in under the 130 in line. Volume: 16,956 in³ under the 17,280 in³ line. Longest side: 84 in under the 96 in line.
- UPS & FedEx maximum sizeWithin the 108 in length and 165 in length + girth maximums.
- USPS size limitLength + girth 36 in is within USPS’s 108 in limit.
- USPS nonstandard feesNone for this size: longest side 12 in is not over 22 in and 324 in³ is not over 2 ft³ (3,456 in³).
- USPS Cubic pricing (commercial)Priority Mail Cubic tier 0.20 and Ground Advantage Cubic tier 0.20 (324 in³ ÷ 1,728 = 0.188 ft³). Priced by tier and zone, up to 20 lb. Cubic calculator →
- DHL Express Oversize PieceClear: longest side 12 in (line: 40 in), second-longest 9 in (line: 32 in).
Rules verified 22 Sep 2026 · sources: FedEx Service Guide 2026 · UPS 2026 Rate and Service Guide (Daily Rates) · USPS DMM 101 (maximum size and weight) · USPS DMM 223 (Priority Mail: DIM weight, cubic, nonstandard fees) · USPS DMM 283 (Ground Advantage — Commercial, cubic) · DHL Express US Service & Rate Guide 2026
Trim one inch
The biggest saving comes from the height: 3 → 2 in drops the FedEx/UPS DIM weight from 3 to 2 lb.
| Change | in³ | DIM ÷139 | Saves | UPS Retail ÷166 | USPS |
|---|---|---|---|---|---|
| Length 12 → 11 in | 297 | 3 lb | no change | 2 lb | none (under 1 ft³) |
| Width 9 → 8 in | 288 | 3 lb | no change | 2 lb | none (under 1 ft³) |
| Height 3 → 2 in | 216 | 2 lb | −1 lb | 2 lb | none (under 1 ft³) |
On a 48 × 40 pallet
16 per layer (4 × 4, 3 in side up), 20 layers in 60 in of stack height = 320 boxes, 60 ft³ in all. The layer covers 90% of the deck.
Assumes a simple column stack, box upright, no overhang, 60 in of boxes on the deck. Interlocked or mixed patterns can fit more; check your carrier’s or warehouse’s height limit. Try mixed patterns, other pallets and heights →
Size tier
Large standard at the lightest. Amazon sets the tier on the greater of unit weight and dimensional weight — here 324 ÷ 139 = 2.33 lb. It’s within 18 × 14 × 8 in and the DIM weight (2.33 lb) is under 20 lb.
Rules verified 22 Sep 2026 · sources: Amazon Seller Central — Product size tiers
Heavier contents can move it up a tier — check with your product’s weight. See the FBA dimensional weight guide for 2026 fees.
An item this size fits inside the USPS Medium Flat Rate Box 2 (13 5/8 × 11 7/8 × 3 3/8 in inside), in some orientation. Flat Rate is priced by the box, not by weight or dimensional weight, up to 70 lb. It also fits: Large Flat Rate Box.