Container Loading Calculator
Estimate how many identical items fit inside a standard shipping container at a given packing efficiency. Use this when planning FCL shipments, warehouse staging, or procurement of packaging materials.
About this calculator
Container loading capacity depends on the container's internal volume, the size of each item, and how efficiently the items can be packed together. The formula is: Items = ⌊(Container Volume (ft³) × 1728 × Packing Efficiency) / (Item Length × Item Width × Item Height)⌋. The 1,728 factor converts cubic feet to cubic inches so all dimensions stay consistent in inches. Packing efficiency (expressed as a decimal, e.g., 0.85 for 85%) accounts for irregular stacking, void space between items, and bracing. A perfect theoretical fill is 1.0, but real-world loads typically range from 0.70 to 0.90. Standard 20-foot containers have roughly 1,172 ft³ of usable volume; 40-foot containers offer about 2,390 ft³. The floor function ensures the result is always a whole number of items.
How to use
You want to load boxes measuring 24 × 18 × 12 inches into a 20-ft container (1,172 ft³) at 80% packing efficiency. Step 1: Convert container volume = 1,172 × 1,728 = 2,025,216 cubic inches. Step 2: Apply efficiency = 2,025,216 × 0.80 = 1,620,173 cubic inches available. Step 3: Item volume = 24 × 18 × 12 = 5,184 cubic inches. Step 4: Items = ⌊1,620,173 / 5,184⌋ = ⌊312.5⌋ = 312 boxes. You can load approximately 312 boxes in one 20-ft container at 80% efficiency.
Frequently asked questions
What packing efficiency percentage should I use for a shipping container calculation?
Packing efficiency varies by item shape and loading method. Uniform rectangular cartons stacked on pallets typically achieve 80–90% efficiency. Irregularly shaped goods, fragile items requiring extra bracing, or mixed-SKU loads may only reach 60–75%. Round or cylindrical items packed in rows achieve roughly 78.5% efficiency theoretically (π/4). Start with 0.85 as a conservative default for standard cartons and adjust downward if your goods require significant void fill or custom dunnage.
How many items fit in a 20-foot vs 40-foot shipping container?
A standard 20-foot container (20' GP) has approximately 1,172 cubic feet of usable internal volume, while a standard 40-foot container (40' GP) offers about 2,390 cubic feet—roughly double. A 40-foot high-cube container adds about 344 extra cubic feet over a standard 40-footer due to its additional foot of height. For the same item size and packing efficiency, a 40-footer holds about twice as many items as a 20-footer, often at a lower cost-per-unit freight rate.
Why does container loading calculation use a floor function instead of rounding to the nearest whole number?
You cannot load a fraction of a physical item into a container—either the item fits completely or it does not. Rounding up would imply loading more items than the available space allows, which is physically impossible and could damage cargo or violate weight limits. The floor function (Math.floor) always rounds down to the nearest complete item count, giving you a safe, achievable loading plan. Any remaining space after the floor calculation can be used for additional smaller items, padding, or bracing.