18 × 18 × 10 in box: dimensions, dim weight and strength
A 18 × 18 × 10 in box holds 3,240 in³ (1.88 ft³) inside. Made in C flute its outside is about 18.31 × 18.31 × 10.47 in, which dimensional weight bills USPS at 29 lb and FedEx at 24 lb.
Key numbers
| Inside (L × W × H) | 18 × 18 × 10 in |
|---|---|
| Inside volume | 3,240 in³ · 1.875 ft³ · 53.1 L |
| Inside, metric | 457 × 457 × 254 mm |
| Perimeter 2(L + W) | 72 in |
| Length + girth, C flute OD | 75.9 in |
Outside dimensions by flute
| Board | Caliper, in | Outside, in | Outside volume, ft³ |
|---|---|---|---|
| E flute | 0.063 | 18.13 × 18.13 × 10.19 | 1.937 |
| B flute | 0.125 | 18.25 × 18.25 × 10.38 | 2 |
| C flute | 0.156 | 18.31 × 18.31 × 10.47 | 2.032 |
| EB double wall | 0.188 | 18.38 × 18.38 × 10.56 | 2.064 |
| BC double wall | 0.281 | 18.56 × 18.56 × 10.84 | 2.162 |
OD ≈ ID + 2 calipers on length and width, + 3 on depth. An estimate: your box maker sets the scores. Convert other sizes.
Dimensional weight
| Carrier | Divisor | Measured, in (C) | DW, C flute | DW, BC double wall |
|---|---|---|---|---|
| USPS | 139 | 19 × 19 × 11 | 29 lb | 29 lb |
| FedEx | 139 | 18 × 18 × 10 | 24 lb | 29 lb |
DW = ⌈L × W × H ÷ divisor⌉ on outside dimensions, after each carrier's own rounding. USPS applies it only above 1,728 in³ (n/a means it bills actual weight). The carrier bills the greater of actual and dimensional weight. Divisors checked on carrier pages 2026-10-27; try your own weight.
Estimated compression strength
| Board | BCT, lbf | After 30 days storage |
|---|---|---|
| 32 ECT B flute | 564 | 338 |
| 32 ECT C flute | 630 | 378 |
| 44 ECT C flute | 866 | 520 |
| 48 ECT C flute | 945 | 567 |
| 48 ECT BC double wall | 1,268 | 761 |
| 61 ECT BC double wall | 1,611 | 967 |
| 71 ECT BC double wall | 1,876 | 1,125 |
Simplified McKee: BCT ≈ 5.87 × ECT × √(caliper × 72). The 30-day column applies Packgent's default 40% storage loss, an assumption. Estimates only; test with ASTM D642.
Pallet pattern on 48 × 40
| Board | Per layer | Layers | Boxes per pallet | Load height, in | Cube used |
|---|---|---|---|---|---|
| C flute | 4 | 5 | 20 | 57.8 | 67% |
| BC double wall | 4 | 5 | 20 | 59.7 | 71% |
Column stacked, no overhang, on a 48 × 40 in deck 5.5 in tall, loaded to 60 in overall. Those three are assumptions you can change in the pallet calculator. Pattern: 18.3125″ along the 48″ side.
Blank size in C flute
| Style | Blank, in | Board, ft² |
|---|---|---|
| 0201 RSC | 73.88 × 28.31 | 14.52 |
| 0200 HSC | 73.88 × 19.16 | 9.83 |
| 0203 FOL | 73.88 × 46.31 | 23.76 |
With one caliper allowance per score. Multiply board area by your board's combined weight (lb/MSF ÷ 1,000) for box weight, or use the box weight calculator.
Sources
- USPS Domestic Mail Manual 223 (Priority Mail prices and eligibility), section 1.4
- FedEx: What is dimensional weight?
- Flute calipers: Foster (1997), Wiley Encyclopedia of Packaging Technology
- McKee, Gander & Wachuta (1963), Paperboard Packaging 48(8)
Last reviewed . See all sources and how Packgent computes.
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