Quick answer
Corrugated plastic (PP fluted / twin-wall polypropylene) sheet comes in 2, 3, 4, 5, 6, 8 and 10 mm. For boxes: use 3 mm for light totes and dividers (up to about 8 kg / 18 lb of contents), 4 mm for standard produce and warehouse totes (8–15 kg / 18–33 lb) and yard-sign blanks, 5 mm for export produce and seafood boxes (15–25 kg / 33–55 lb), 6 mm for heavy-duty totes and pallet sleeves, and 8–10 mm for bulk harvest bins that carry 500–1,200 kg on a pallet base. Thickness alone is not the spec — always state the grammage (g/m²) too, because a 4 mm sheet can be made anywhere from 600 to 1,000 g/m² and the heavier sheet is roughly 50% stiffer.
Corrugated plastic thickness chart: mm, inches, weight and typical uses
Corrugated plastic is extruded, so the same nominal thickness can be produced at different weights by changing the wall (skin) thickness and the rib spacing. The table below shows the ranges that packaging factories actually run, with the sheet weight for a standard 48 × 96 in (1,220 × 2,440 mm) blank at a mid-range grammage.
| Thickness | Inches | Typical grammage (g/m²) | Weight of a 48 × 96 in sheet | Cardboard equivalent | Typical uses |
|---|---|---|---|---|---|
| 2 mm | 0.079 in (≈ 5/64") | 300–450 | 1.1 kg / 2.5 lb (at 380 g/m²) | E-flute | Layer pads, dividers, folder inserts, small die-cut pieces, printed POP |
| 2.5–3 mm | 0.098–0.118 in (≈ 1/8") | 450–650 | 1.6 kg / 3.6 lb (at 550 g/m²) | B-flute | Light totes, archive boxes, mailers, economy sign blanks, protection board |
| 4 mm | 0.157 in (≈ 5/32") | 650–1,000 | 2.2 kg / 4.9 lb (at 750 g/m²) | C-flute | Standard US yard-sign blank; RPC-style produce totes; warehouse and picking totes; floor protection |
| 5 mm | 0.197 in (≈ 3/16") | 900–1,200 | 3.0 kg / 6.6 lb (at 1,000 g/m²) | BC double-wall | Export produce boxes (banana, avocado, grape, vegetables), fish totes, returnable shippers |
| 6 mm | 0.236 in (≈ 1/4") | 1,100–1,500 | 3.9 kg / 8.5 lb (at 1,300 g/m²) | Heavy double-wall | Heavy-duty totes, seafood totes with 30 kg+ payloads, pallet sleeves, large signs |
| 8 mm | 0.315 in (≈ 5/16") | 1,400–2,000 | 5.1 kg / 11.2 lb (at 1,700 g/m²) | Triple-wall | Sleeve-pack bins, automotive dunnage, long-run returnable containers |
| 10 mm | 0.394 in (≈ 3/8") | 1,800–2,500 | 6.3 kg / 13.8 lb (at 2,100 g/m²) | Triple-wall + | Bulk harvest bins (48 × 40 in), heavy pallet sleeves, structural panels |
Sheet weight = grammage × 2.98 m² (the area of a 48 × 96 in sheet). Standard sheet sizes are 48 × 96 in (1,220 × 2,440 mm) and 1,000 × 2,000 mm; extruders can run custom widths up to about 2,400 mm and any cut length, so box blanks are normally cut to size at the factory rather than from standard sheets.
How much weight can a corrugated plastic box hold? Load guide by wall thickness
A box is not a sheet: what it can carry depends on wall thickness and grammage, flute (rib) direction, footprint, whether the corners are glued, welded, riveted or stitched, and how high it is stacked. The figures below are the conservative working ranges we use when quoting new box designs; they assume flutes running vertically in the side walls, room temperature and a normal pallet stack.
| Wall thickness | Contents per box (working) | Typical stacking | Expected reuse life | Best-fit products |
|---|---|---|---|---|
| 2–2.5 mm | ≤ 3 kg / 7 lb | Not for stacked loads | Single trip or protective use | Inserts, dividers, partitions, small mailers |
| 3 mm | ≤ 8 kg / 18 lb | 3–4 high | 5–15 trips | Light produce totes, archive and file boxes, small parts totes |
| 4 mm | 8–15 kg / 18–33 lb | 5–6 high | 10–30 trips | 40 × 30 cm and 60 × 40 cm produce totes, warehouse picking totes, retail-ready shippers |
| 5 mm | 15–25 kg / 33–55 lb | 6–8 high, cold chain | 20–50 trips | 18–22 kg banana and vegetable export boxes, avocado and citrus boxes, 40–60 lb fish totes |
| 6 mm | 25–35 kg / 55–77 lb | 8 high (sleeve packs on pallets) | 30–80 trips | Heavy seafood totes, meat and poultry totes, pallet sleeves for 300–500 kg loads |
| 8 mm | 500–800 kg on a pallet base | 2–3 pallets high | 50–100+ trips | Collapsible sleeve-pack bulk bins, automotive and appliance dunnage |
| 10 mm | 800–1,200 kg on a pallet base | 2–3 pallets high | 100+ trips | Bulk harvest bins for apples, citrus, potatoes and onions; heavy industrial sleeves |
Four rules of thumb when sizing wall thickness
- Add 1 mm for cold storage. Polypropylene stiffens but loses impact strength below about −10 °C (14 °F); for blast-chilled seafood or frozen cold rooms specify 5 mm instead of 4 mm, or ask for an impact-copolymer PP grade.
- Add 1 mm for wet loads. A wet product (iced fish, hydro-cooled vegetables) is heavier and the box is handled with wet hands and forklifts; a box that is fine at 4 mm dry usually needs 5 mm in a packhouse.
- Grammage beats thickness. A 4 mm / 900 g/m² sheet outperforms a 5 mm / 900 g/m² sheet in edge-crush and stacking tests because the skins are thicker. If a supplier quotes thickness without grammage, ask for it.
- Flute direction is free strength. Running the ribs vertically in the side walls raises box compression strength by roughly 30–40% versus horizontal ribs, at zero material cost — it only has to be specified on the die-line.
Sheet specification checklist: what to put on a corrugated plastic RFQ
Buyers who send a full specification get a comparable quote first time. For corrugated polypropylene sheet or box blanks, state:
- Thickness and grammage — e.g. "4 mm, 800 g/m²" — not thickness alone.
- Sheet or blank size and flute direction — e.g. 1,220 × 2,440 mm, flutes running along the 2,440 mm length.
- Color — natural (translucent), white, black or Pantone match; white and colored sheets carry 2–5% masterbatch and cost slightly more than natural.
- Additives — UV stabiliser for outdoor signs and open-field harvest bins, anti-static for electronics dunnage, flame-retardant for building sites, food-grade virgin resin for produce and seafood contact.
- Surface treatment — corona treatment (≥ 38 dyne) if the sheet will be screen or digitally printed; ask for the treatment date because corona fades after a few months.
- Converting — die-cut, creased, printed, ultrasonically welded, riveted or stitched corners; hand holes; lids or drop-fronts.
- Quantity and delivery — pallet or 20 ft / 40 ft container quantities; a 40 ft HQ container holds roughly 2,000–2,400 m² of 4 mm sheet or 8,000–12,000 folded 40 × 30 cm totes.
Sign blanks: which thickness for yard signs, real-estate signs and event boards?
In the United States the standard corrugated plastic sign blank is 4 mm (0.157 in), typically 650–750 g/m² for economy political and real-estate signs and 900–1,000 g/m² for signs that must survive a full season outdoors. 3 mm boards are sold as a lower-cost option but flex in wind above about 24 × 18 in. Larger boards — 24 × 36 in and 36 × 48 in — move to 6 mm or 10 mm with vertical flutes so that H-stakes and grommets do not tear through. See our yard sign size guide for standard sizes and stake spacing.
Produce and seafood boxes: choosing between 4, 5 and 6 mm
For fresh produce the decision is mostly about payload and moisture. A 40 × 30 × 15 cm returnable tote for tomatoes, peppers or berries carrying 8–12 kg runs happily at 4 mm. An 18–22 kg banana, avocado or vegetable export box that is stacked eight high in a reefer container needs 5 mm and vertical flutes. Fish totes see iced, wet, 20–35 kg loads and forklift handling, so 5 mm is the minimum and 6 mm is common for 60–100 lb totes; our fish tote sizes guide lists the standard footprints. Compared with waxed corrugated cartons, a 5 mm PP box costs more per unit but is washable, recyclable and reusable 20–50 times, which is why growers switching away from wax usually recover the difference within one season.
| Application | Recommended thickness | Grammage | Notes |
|---|---|---|---|
| Berry / tomato / pepper totes, 40 × 30 cm | 4 mm | 750–850 g/m² | Vented walls, vertical flutes, nestable when empty |
| Banana / avocado / citrus export box, 18–22 kg | 5 mm | 950–1,100 g/m² | Column-stack design, ventilation matched to ripening-room airflow |
| Fish tote, 40–60 lb | 5 mm | 1,000–1,150 g/m² | Drain holes, welded corners, food-grade virgin PP |
| Fish / meat tote, 60–100 lb | 6 mm | 1,200–1,400 g/m² | Riveted or welded corners, reinforced hand holes |
| Harvest bin, 48 × 40 in, 800–1,200 lb | 8–10 mm sleeve | 1,700–2,200 g/m² | Used with a plastic or wooden pallet base; see the harvest bins cost guide |
| Yard sign blank, 24 × 18 in | 4 mm | 650–1,000 g/m² | UV-stabilised, corona-treated for printing |
How thickness changes the price
Corrugated plastic is priced by weight of resin, so cost scales with grammage far more than with nominal thickness. Using a 4 mm / 750 g/m² sheet as an index of 100, a 3 mm / 550 g/m² sheet is roughly 75, a 5 mm / 1,000 g/m² sheet roughly 130, a 6 mm / 1,300 g/m² sheet roughly 170 and a 10 mm / 2,100 g/m² sheet roughly 270. The practical lesson: never "round up" thickness for safety without a reason, but do pay for the extra grammage when the box will be reused, because the first 100 g/m² of extra skin is what turns a 10-trip box into a 30-trip box.
Origin also matters for US buyers in 2026. Corrugated plastic boxes and sheets from China and Vietnam are covered by the 2026 US antidumping and countervailing duty (AD/CVD) case; Philippine-origin product is outside the scope of that case, so it avoids the AD/CVD duties, while the standard 19% reciprocal tariff on Philippine goods still applies. Fuxing produces PP corrugated sheet and boxes in Davao and Manila, Philippines for exactly this reason — see PP corrugated boxes from the Philippines.
Frequently asked questions
What thickness of corrugated plastic should I use for a box?
Use 3 mm for light totes and dividers up to about 8 kg (18 lb), 4 mm for standard produce and warehouse totes carrying 8–15 kg (18–33 lb), 5 mm for 15–25 kg (33–55 lb) export produce and seafood boxes, 6 mm for heavy-duty totes above 25 kg, and 8–10 mm sleeves for bulk bins carrying 500–1,200 kg on a pallet. Always specify grammage (g/m²) alongside thickness, and add 1 mm for cold-storage or wet loads.
How thick is a standard yard sign or sign blank?
The standard corrugated plastic sign blank in the US is 4 mm (0.157 in, about 5/32"), usually 650–1,000 g/m². 3 mm blanks are a lower-cost option for small signs, and 6 mm or 10 mm boards are used for 24 × 36 in and larger signs so that stakes and grommets do not tear through.
How much weight can a 4 mm corrugated plastic box hold?
A well-designed 4 mm tote with vertical flutes and 750–900 g/m² sheet carries 8–15 kg (18–33 lb) of contents and stacks five to six high at room temperature. Push the payload above 15 kg, chill it below freezing, or stack it eight high in a container and you should move to 5 mm.
What does g/m² (grammage) mean for corrugated plastic, and why does it matter more than thickness?
Grammage is the weight of one square metre of sheet. Because corrugated plastic is extruded, a 4 mm sheet can be made at 600 g/m² with thin skins or at 1,000 g/m² with thick skins; the heavier sheet is around 50% stiffer and far more crush-resistant even though the thickness is identical. Two quotes for "4 mm sheet" are only comparable when the grammage matches.
Is 5 mm or 6 mm better for produce and seafood boxes?
5 mm at 950–1,150 g/m² is the standard for 18–22 kg produce export boxes and 40–60 lb fish totes. Choose 6 mm at 1,200–1,400 g/m² when the payload exceeds about 25 kg (55 lb), the box is forklift-handled while wet, or you want 50 or more reuse cycles.
Are corrugated plastic sheets and boxes affected by the 2026 US AD/CVD duties?
The 2026 US antidumping and countervailing duty case covers corrugated plastic boxes and sheet from China and Vietnam. Philippine-origin corrugated plastic is outside the scope of that case and avoids the AD/CVD duties; the standard 19% reciprocal tariff on Philippine goods still applies. Fuxing supplies sheet and finished boxes from its Philippine plants in Davao and Manila.
Need a thickness recommendation for your box?
Send us the product, payload, stacking height and whether it goes through cold storage. We will recommend thickness, grammage and flute direction, and quote within 12 business hours from our plants in China, Vietnam and the Philippines. Free samples for qualified programs.
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