Step 1: Get the size right
Box size is the decision that quietly drives everything else: protection, shipping cost, and how much you pay per box. Start here.
Measure your product in inches as Length × Width × Height (L is the longest side of the opening, W the shorter side, H the depth). Corrugated shipping boxes are always listed by interior dimensions, so you're measuring the space your product needs, not the box's outside.
Then decide how much room to add:
- Non-fragile, snug-fitting items (books, tools, apparel, retail stock): choose a box that fits closely with minimal extra space. A snug box uses less fill, resists crushing better, and costs less to ship.
- Fragile or oddly shaped items: add roughly 2 inches total to each dimension to leave room for cushioning on all sides (about an inch of protection around the product).
Watch dimensional weight. Couriers bill the greater of a parcel's actual weight or its "dimensional" (volume-based) weight. An oversized box full of air can cost more to ship than the product inside it. Right-sizing is the single easiest way to cut recurring shipping costs — which is why stocking a few well-chosen sizes beats forcing everything into one big box.
Packaging Shop stocks over 100 standard sizes, from small 4×4×4" cubes up to 24×24×24", so you can match the box to the product instead of the other way around. If nothing fits, we make custom sizes to spec.
Step 2: Understand box strength — what "32 ECT" means
Every standard box we carry is rated 32 ECT. That number is worth understanding, because it tells you exactly what the box can handle.
ECT stands for Edge Crush Test — a measure of how much stacking pressure the walls can take, expressed in pounds per inch of edge. A 32 ECT box withstands 32 lbs of force per inch before the walls buckle. In plain terms: 32 ECT is the workhorse standard for single-wall corrugated, trusted for everyday shipping, storage, and stacking. It's strong enough for the large majority of B2B and ecommerce loads while keeping the shipping box light and affordable.
Our 32 ECT boxes are also FSC-certified and fully recyclable — the board comes from responsibly managed forests, which matters if sustainability shows up in your customer or procurement requirements.
Step 3: ECT vs. Mullen (burst) — which rating should you look at?
You'll see corrugated rated two ways. Here's the difference in one line each:
- ECT (Edge Crush Test) measures stacking strength: how much weight the shipping box can bear from the top down. This is what matters when boxes are palletized or stacked on warehouse racks.
- Mullen / Burst Test measures puncture and rough-handling resistance: how well the walls survive impacts and pressure. This matters most for heavy, dense contents shipped as single parcels.
For most operations, 32 ECT covers both jobs well. As a rough equivalence, a 32 ECT single-wall box performs in the range of a traditional 200# burst-rated shipping box, but uses less fiber — which is why ECT-rated board has become the modern standard. Unless you're shipping unusually heavy or dense items, 32 ECT is the right call.
Step 4: How much weight can a corrugated shipping box hold?
A practical rule for standard 32 ECT single-wall: it reliably carries up to about 65 lbs of gross weight when the shipping box is correctly sized, evenly packed, and sealed with quality tape. Two things change that number in practice:
Factor and Effect on capacity
- Stacking / warehouse storage
- Shipping boxes bear weight from above — ECT (stacking strength) is the limit, so don't over-stack tall towers.
- Empty space inside | A half-full shipping box crushes far more easily than a snug one. Fill voids or size down.
- Weight distribution | Concentrated or shifting weight stresses seams. Pack evenly and tape well.
- Humidity / cold storage | Damp or freezing conditions reduce strength. Store shipping boxes dry and flat.
If your product is heavier than ~65 lbs, or you're stacking heavy pallets several high, that's your signal to move up from standard single-wall.
Step 5: When you need more than standard single-wall
Standard 32 ECT single-wall handles most loads, but step up when:
- Individual items exceed roughly 65 lbs,
- Contents are dense, sharp, or high-value/fragile, or
- You're stacking heavy pallets in long-term storage.
In those cases you want double-wall corrugated (two layers of fluting for far higher stacking and puncture strength). We don't stock double-wall off the shelf, but we produce it as a custom order: tell us the dimensions and weight and we'll spec it for you.
Step 6: Match your packaging tape and stretch wrap to the shipping box
The right shipping box only protects your product if it's sealed and stabilized properly:
- Packing tape: our 2" × 110 yd, 2.0 mil tape (clear or tan) is built for reliable seals under load. Use the H-taping method: seal the center seam and both edge seams, top and bottom — for anything heavier or in transit for more than a day. Sold by the roll or by the case of 36 for high-volume shippers.
- Stretch wrap: for palletized loads, our 16" and 20" hand rolls (high puncture resistance and strong cling) stabilize stacked boxes so they arrive as one unit instead of shifting in transit.
Your GTA corrugated shipping box checklist
Before you order, confirm:
1. Size — measured L×W×H, snug or +2" for cushioning
2. Strength — 32 ECT for standard loads; custom double-wall if over ~65 lbs or fragile
3. Quantity — buy at a price break (we sell in bundles, with better per-box pricing at higher volumes)
4. Sealing — right tape and taping method for the weight
5. Delivery — local delivery, shipping or North York / Mississauga pickup for GTA businesses