Carton Calculator

What it solves

Working out carton sizes and units per carton by hand is slow and easy to get wrong. Get it wrong and you end up over the carrier size limit, over the weight limit, paying for volumetric weight you did not need, or with a carton that deforms in transit and fails the size check at the depot.

The calculator tries all six ways your item can sit in the carton, across every sensible stacking pattern, and applies your buffer gap, deformation allowance, side limits, girth limit and weight range. It returns the compliant plan with the lowest chargeable weight per unit, which is the cheapest way to ship the goods.

Basic inputs

Four numbers are enough for a first answer. No advanced settings needed.

Item length (cm)

Longest side of one item.

Item width (cm)

Second-longest side of one item.

Item height (cm)

Shortest side of one item.

Single unit gross weight (kg)

Weight of one item, carton not included.

Advanced settings

Open these when your forwarder or warehouse works to different limits than our defaults.

Carton buffer gap (cm)

Gap left between stacked items. Default 0.75cm. Use 0.5cm for small general goods and 1cm for fragile goods so they are not crushed against each other.

Max allowed carton weight (kg)

Heaviest a single carton may be. Default 21kg, which keeps you under the usual overweight surcharge threshold.

Minimum carton weight (kg)

Lightest a carton may ship at, so you are not paying to send near-empty cartons. A carton also passes if its volumetric weight is over 12kg, which covers light but bulky goods. Set it to 0 if your channel has no floor.

Minimum charge weight (kg)

The least a courier will bill a single carton at, however little it actually measures. Default 12kg, the usual LCL courier minimum. This does not change the packing plan or the chargeable weight shown, it only adds a note when the carton comes out under the floor. Set it to 0 for channels with no per-carton minimum, such as trucking.

Max stack layers

How many cartons high your goods are stacked in the container or the warehouse. Default 7. Only the cartons above the bottom one press down on it, so a stack of 7 loads the bottom carton with 6. This is what decides the board strength we recommend, so lower it if you know your goods travel in shorter stacks.

Shipping method

Sea LCL, Sea FCL or Air. Sets the safety margin applied to the carton strength. Sea LCL gets the largest margin because it is the longest transit, is handled the most and shares space with other cargo; air gets the smallest. It does not change the packing plan, only the board we recommend.

Max quantity per carton

Most units allowed in one carton, whatever the size and weight limits would permit. Default 150, which matches the usual Amazon FBA cap.

Carton deformation tolerance (cm)

Reserved allowance for physical carton deformation once the carton is packed and stacked. Default 2cm. It is deducted from every side limit and from the girth limit, so the carton still measures within spec when it reaches the depot, and it is added to each side for the volumetric weight with deformation tolerance in the result. This is not the gap between items, which is the carton buffer gap above.

Max longest / second / third side (cm)

Your carrier’s published side limits. The deformation tolerance comes off each one before the check runs.

Maximum girth (cm)

Your carrier’s girth limit, where girth = length + 2 × width + 2 × height.

How to use it

• Enter the length, width, height and gross weight of one item. All four must be above zero.
• Optional: open Advanced settings and match the deformation tolerance, buffer gap and size or weight limits to your forwarder’s rules. The defaults suit most channels.
• Press Calculate best carton plan.
• Read the result: units per carton, outer carton size, actual weight, volumetric weight with and without the deformation tolerance, chargeable weight, chargeable weight per unit, item orientation and stack layout.

Reading the result

Units per carton

How many items go in one carton under the cheapest compliant plan we found.

Outer carton size

Finished carton dimensions, buffer gaps included.

Total actual weight

Combined weight of all items in the carton.

Volumetric weight

Ocean LCL volumetric weight: length × width × height ÷ 6000.

Volumetric weight with deformation tolerance

The same sum with the deformation tolerance added to each side, so you can see what the carton bills at if it deforms to the full reserved allowance.

Chargeable weight

The greater of the total actual weight and the volumetric weight with deformation tolerance. This is what you are billed on. We use the deformation figure because a packed carton almost always measures larger at the depot than its design size, so this lands closer to the weight you are actually invoiced for.

Chargeable weight per unit

Chargeable weight divided by units per carton. Use this to cost a single item.

Courier minimum note

Appears only when the chargeable weight lands under the minimum charge weight. It means a courier would bill the floor instead of the calculated figure. Trucking has no such minimum, so the same plan still works if you ship by truck.

Recommended carton wall and flute type

The lightest corrugated board that will survive the stack: 3, 5 or 7 layers, with the flute type to order it in. Worked out with the McKee formula from the carton footprint, the weight of the cartons above it and the safety margin for your shipping method. We recommend the cheapest board that is strong enough, never a heavier one than the load needs.

Compression strength needed

How much downward force the bottom carton has to survive, in newtons, once the stack and the safety margin are accounted for. Useful if you are specifying board with a supplier: quote them this figure and they can match it from their own stock.

Item orientation

Which way each item sits, as length × width × height inside the carton.

Stack layout

How many items along each carton axis.

Notes

• The defaults suit Easy China Warehouse and most forwarder channels. A few channels have their own rules, so adjust the advanced settings for those.
• If nothing compliant comes back, the message tells you which limit blocked it, down to the single side where one side alone is the problem. Usually it is the minimum carton weight on a light product, or the side limits on a bulky one.
• One item cannot weigh more than the max carton weight. If yours does, talk to us about the right channel for it.
• For help tuning the settings for your channel, email [email protected].