How PackDev calculates

PackDev estimates box compression strength, stacking height, the pallet pattern and axle loads from standard engineering relations and reference tables. The result is an engineering estimate for choosing and comparing options.

It does not replace a laboratory compression test, a transport test or the professional responsibility of the engineer who approves the packaging. Actual board strength can be lower than calculated.

Which standard is applied where →

Box compression strength (BCT) is estimated with the simplified McKee formula from three inputs: the edge crush strength of the board, the wall thickness and the box perimeter.

BCT = 5.876 × ECT × √(t × Z), Z = 2 × (L + W)

• BCT — box compression strength, N
• ECT — edge crush strength of the board, N/m (entered in kN/m)
• t — wall thickness, m (entered in mm)
• Z — box perimeter, m; L and W are the box length and width

Units matter. The constant 5.876 holds for one consistent set: with ECT in N/m and t, Z in metres, BCT comes out in newtons. ECT in kN/m with t and Z in millimetres gives the same number, because kN/m × mm = N. Mixing the two sets, N/m with millimetres, is off by a factor of 1000.

Wall thickness: when a flute is selected, its typical thickness is used; with no flute selected, the thickness you enter is used.

ECT: selecting a flute fills in the ECT of a typical catalogue grade (GOST R 52901 or DIN tables); replace it with the value from the board supplier’s data sheet when you have one.

Humidity, transport mode and storage time each weaken a box. Each is a multiplier k, and the combined factor is their product.

k = k_h × k_t × k_s

r = (1 − k) × 100 %

On the box strength page the combined factor becomes the BCT reduction r, rounded to a whole percent, until you enter your own. The palletizer starts from r = 20 %, a typical warehouse allowance.

The reduced strength is divided by the safety factor and converted into the mass one box may carry. The bottom box carries every box above it, so a column holds that many boxes plus the bottom one.

BCT_eff = BCT × (1 − r / 100); P = BCT_eff / SF; m = P / g; n = ⌊m / m_box⌋ + 1

• r — BCT reduction for conditions, %
• SF — safety factor, 6 by default
• P — load one box may carry, N; m — the same load in kg, g = 9.81 m/s²
• m_box — mass of one filled box, kg; n — boxes in a column, the bottom one included

The safety factor and the reduction are separate allowances. When both are high, the calculator warns that humidity or storage may be counted twice.

A box 400 × 300 mm of board 1.30 C (C flute), filled mass 10 kg, with the palletizer defaults: reduction 20 % and safety factor 6.

1. 1. Perimeter

   Z = 2 × (400 + 300) = 1400 mm = 1.4 m

2. 2. Wall and board

   t = 4 mm = 0.004 m; ECT = 4.5 kN/m = 4,500 N/m

3. 3. Box compression strength

   BCT = 5.876 × 4,500 × √(0.004 × 1.4) ≈ 1,979 N

4. 4. Strength after the reduction

   BCT_eff = 1,979 × (1 − 20 / 100) ≈ 1,583 N

5. 5. Load one box may carry

   P = 1,583 / 6 ≈ 263.8 N; m = 263.8 / 9.81 ≈ 26.9 kg

6. 6. Boxes in a column

   n = ⌊26.9 / 10⌋ + 1 = 3

The box strength page gives the same numbers, up to rounding, for these inputs with the reduction set to 20 %.

• Each layer is tiled with column and brick patterns, and the densest valid pattern found is offered; a layout of your own stays available in manual layer assembly.
• By default brick layers start from layer 4; the layers below repeat the base pattern as columns.
• The share of each box footprint resting on the layer below is checked layer by layer and shown in the result; if you forbid unstable patterns, a brick layer below the minimum support share falls back to columns, with a warning naming the layer.
• Layers stop at whichever limit comes first: the height cap (1800 mm by default, deck included), the payload cap of the pallet, or the column limit from box strength.
• Boxes overhanging the pallet edge are flagged: overhang weakens the stack relative to the BCT estimate.

C = A_base / A_pallet × 100 %

Pallet coverage C: the area covered by the boxes of the base layer divided by the deck area.

• Pallets are placed in rows across the cargo space in delivery-stop order, heaviest first within a stop, so the first stop sits at the doors.
• The loaded block is pushed against the front wall, the way a part load is secured.
• Axle loads follow a two-point lever model between the real supports of the vehicle — a truck's axles, or a semi-trailer's kingpin and axle group; each is compared with the support limit of the vehicle preset, and the total with its payload.

F_front = Σ m × (y − y_r) / (y_f − y_r); F_rear = Σ m − F_front

m — mass of a pallet, y — its distance from the doors, y_f and y_r — positions of the front and rear support from the doors (a support may stand outside the body). A pallet over the rear support loads only that one; a pallet behind it unloads the front.

Not calculated: load securing (EN 12195-1) and the rigidity of the load unit (EUMOS 40509).

• Nesting counts how many units fit in the box by orthogonal packing, trying every orientation of the unit.
• Box constructions come from the FEFCO code catalogue.