Container OptimizerContainer Load Planning Calculator
Plan how many timber packages fit in a shipping container by both volume and weight. Identify the limiting factor, utilization rates and avoid overweight penalties on export and import shipments.
Why this calculation matters
Load planning decides whether you pay for air or leave payload unused. Dense hardwood weighs out; light softwood cubes out.
Container Optimizer
Container Load Planning Calculator
Real-world packing, accounts for gaps. 85-92% typical.
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About Container Optimizer
Shipping timber by container is limited by two ceilings: the physical volume and the weight payload. Dense hardwood usually hits the weight limit long before the container is full, while light or bulky packs run out of space first. This tool works out how many packages fit, which limit you hit, and your volume and weight utilization - so you load efficiently and avoid overweight penalties. It answers the shipping desk's daily question — how much fits in a 40ft container — from your package sizes, weight limits and container loading capacity. Shipping teams also use it as a container stuffing plan before booking — checking container utilization for a mixed load is faster here than in a spreadsheet, and it makes container planning conversations with the CHA much shorter.
Where Is This Used?
Formulas & Standard Sizes
20ft GP: 5898 x 2352 x 2393 mm, ~28.2 t payload, 33.2 m340ft HC: 12032 x 2352 x 2698 mm, ~26.5 t payload, 76.4 m3Fit by volume = floor fits x fill factor (best of 6 rotations)Fit by weight = floor(Payload / Package weight)Actual = minimum of volume-fit and weight-fitHow the calculation works
Two ceilings apply at once and only one of them binds. Dense hardwood hits the payload limit with the container half empty; light or bulky stock fills the space long before the weight matters.
Show the formula
For each orientation, packages per container = floor(length/pL) x floor(width/pW) x floor(height/pH). The best orientation is taken, reduced by the fill factor, then capped by floor(payload / package weight). The lower of the volume and weight limits governs.Rectangular packages in a rectangular container. Dunnage, securing materials, pack irregularity and door-opening restrictions are not modelled.
References and what each one provides
- ISO 668International Organization for StandardizationInternal dimensions and rated payload for 20ft and 40ft general-purpose containers.
Unverified values are marked as such rather than presented as sourced.
Limitations of this calculation
Plans loading from nominal pack dimensions and standard container internals. It does not account for dunnage, securing materials, pack irregularity, door-opening restrictions, or carrier-specific payload limits.
Do not use this for Customs declaration, bill of lading figures, or securing and lashing design.
Figures are engineering estimates from the inputs and assumptions shown. Verify against the actual material and, where the result affects structure or safety, against a qualified professional.
- ISO 20ft GP internal dimensions 5898 × 2352 × 2393 mm, 28,200 kg payload
Formula checked against the sources above by an automated regression test (tests/verify-phase2.js) that derives each expected value independently of this page. Last reviewed .
How to use this tool
- Enter the trade details below, then press Calculate.
- Pick your container type and stackable? from the dropdown.
- Fill in fill factor, package length, package width, package height.
- Press Calculate.
Worked example
Common mistakes to avoid
- Loading by volume alone. A 20ft container fills up by weight long before it fills by space with dense woods like balau — check both limits.
- Forgetting dunnage, stickers and pallet thickness. They eat 5–10% of the space you thought you had.
- Using nominal sizes instead of actual sizes. Planed timber is smaller than its trade name, so the real stack is smaller too.
Frequently Asked Questions
Wood species data
Density, hardness and movement for 60 timbers