Free freight tool
Container Load Calculator for Carton Fit
Estimate identical-carton capacity for 20ft, 40ft and high-cube containers. The calculator tests six box rotations and compares dimensional fit with payload capacity.
Estimated containers required
Enter carton dimensions
Best grid orientation: 0 × 0 × 0 m. Door 2.34 × 2.58 m: passes. Spatial maximum 0; weight maximum not calculated. Cargo 0 CBM / 0 kg versus nominal 76.3 CBM / 26,460 kg payload.
This is a deterministic identical-carton grid feasibility check. It accounts for internal dimensions, door aperture, permitted rotations and payload, but not pallets, mixed-SKU optimization, bracing, axle distribution or dangerous-goods segregation. Confirm the carrier’s equipment sheet and loading plan.
Recommended next step
Carry the selected equipment and loading assumptions into shipping instructions.
Short answer
How many cartons fit in a container
Divide the container's usable internal volume by the carton volume, then check the answer against payload. A 20ft general-purpose container holds roughly 33 CBM and about 28 tonnes; a 40ft holds roughly 67 CBM, and a 40ft high cube roughly 76 CBM. Real loads reach about 80–85% of nominal volume once orientation, pallets, dunnage and door clearance are accounted for, so treat the theoretical count as a ceiling rather than a plan.
- 20ft GP ≈ 33.2 CBM · 28,200 kg payload
- 40ft GP ≈ 67.7 CBM · 26,600 kg payload
- 40ft HC ≈ 76.3 CBM · 26,400 kg payload
- 45ft HC ≈ 86.0 CBM · 27,700 kg payload
20ft and 40ft Container Carton Capacity
- Estimate identical-carton capacity
- Compare 20GP, 40GP, 40HC and 45HC equipment
- Test six carton rotations
- Identify whether space or payload controls
Container Fit Calculation Method and Limits
The tool tests six orthogonal carton rotations against approximate internal equipment dimensions and separately compares the resulting spatial count with payload capacity.
This is an orthogonal fit estimate, not a mixed-SKU or operational stow plan. Door clearance, dunnage, load distribution and safe handling still apply.
Container internal dimensions and capacity
Every fit calculation starts from internal dimensions, not the external size the equipment is named after. A '20ft' container is 20 feet long on the outside; inside, corrugations, corner castings, flooring and door frames take space away. The figures below are representative of standard dry equipment in general circulation and are what this calculator uses, but individual boxes vary by manufacturer and age, and the door opening is always narrower and lower than the internal cross-section.
Payload matters as much as volume. Maximum gross weight is a regulated limit for the container as a unit; payload is that limit minus the tare weight stencilled on the door. Dense cargo hits the payload ceiling long before it fills the space, and road weight limits in the origin or destination country frequently bite before the container limit does.
| Equipment | Internal L × W × H (m) | Nominal capacity | Typical tare | Typical payload | Door opening W × H (m) |
|---|---|---|---|---|---|
| 20ft general purpose (22G1) | 5.90 × 2.35 × 2.39 | ≈ 33.2 CBM | ≈ 2,200 kg | ≈ 28,200 kg | 2.34 × 2.28 |
| 40ft general purpose (42G1) | 12.03 × 2.35 × 2.39 | ≈ 67.7 CBM | ≈ 3,800 kg | ≈ 26,600 kg | 2.34 × 2.28 |
| 40ft high cube (45G1) | 12.03 × 2.35 × 2.69 | ≈ 76.3 CBM | ≈ 3,900 kg | ≈ 26,400 kg | 2.34 × 2.58 |
| 45ft high cube (L5G1) | 13.55 × 2.35 × 2.69 | ≈ 86.0 CBM | ≈ 4,800 kg | ≈ 27,700 kg | 2.34 × 2.58 |
Indicative figures for planning. Always confirm the tare and maximum gross weight stencilled on the specific container, and confirm road weight limits for the origin and destination legs separately.
How the calculator tests carton fit
A carton can sit in a container in six orthogonal orientations — each of the three dimensions can point along the container length, and for each of those the remaining two can be swapped. The calculator evaluates all six, and for each one divides the container length, width and height by the corresponding carton dimension, discards the remainder, and multiplies the three whole numbers together. The best orientation is reported.
This is a block-stacking model: identical cartons, all facing the same way, stacked in a rectangular grid. It deliberately does not attempt clever mixed-orientation packing, because a stow that only works if the loading crew rotates every third carton is not a stow that survives contact with a real warehouse at 6am.
- 1Enter the carton length, width and height in your working unit, plus the weight of one carton.
- 2Enter how many cartons you actually have, so the calculator can tell you whether they fit rather than only how many would.
- 3Select the equipment type, or enter custom internal dimensions and payload if you are loading a non-standard box.
- 4Read the spatial count and the weight count separately — the smaller of the two is your real answer.
- 5Apply a utilisation allowance before you commit: for floor-loaded cartons, plan around 85% of the theoretical count.
Space count vs weight count
The calculator reports both a dimensional maximum and a payload maximum. When the payload figure is lower, your cargo is weight-constrained: adding volume changes nothing and you need more equipment, not better packing. When the spatial figure is lower, your cargo is volume-constrained and carton redesign or better orientation genuinely helps.
Pallets per container
Most cargo does not travel as loose cartons. If you are palletising, the pallet footprint — not the carton — determines the base layer, and the number of layers depends on pallet height against the internal height, minus clearance for the forklift and any top load restrictions.
The two dominant footprints are the EUR/EPAL pallet at 1200 × 800 mm and the industrial or GMA pallet at 1200 × 1000 mm. The counts below are single-layer floor positions for standard equipment; double-stacking doubles them if the cargo, pallet strength and height allow it.
| Equipment | EUR pallet 1200 × 800 | Industrial pallet 1200 × 1000 |
|---|---|---|
| 20ft general purpose | 10–11 | 9–10 |
| 40ft general purpose | 23–25 | 20–21 |
| 40ft high cube | 23–25 | 20–21 |
| 45ft high cube | 27 | 24 |
Counts depend on whether pallets are loaded straight or in a mixed pinwheel arrangement, and on whether overhang is acceptable. Confirm with the loading warehouse before booking equipment.
Why real loads never reach the theoretical number
Nominal capacity assumes a perfect rectangular prism of cargo filling every cubic centimetre. No load achieves that. Understanding where the space goes is what turns a calculator result into a booking you can defend.
- Door clearance: the doorway is roughly 100 mm narrower and 110 mm lower than the internal cross-section, so the last tier often cannot be loaded to full height
- Corrugated side walls take a few centimetres of usable width at intervals along the box
- Cartons bulge — a nominally 400 mm carton packed tight measures more, and the error compounds across twenty rows
- Dunnage, airbags, lashing and edge protection consume space that the calculator does not model
- Cargo cannot be stacked above its own crush rating, which frequently caps height before the ceiling does
- Weight has to be distributed evenly along the floor; a dense product loaded only at one end can exceed axle limits even when total payload is legal
- Reefer equipment loses internal volume to the machinery and must keep the T-floor and air return clear, so it holds materially less than a dry box of the same nominal size
This is a fit estimate, not a stow plan
A stow plan is a safety document. It accounts for load distribution, securing, crush strength, compatibility and handling, and it is produced by people who can see the cargo. Use this calculator to choose equipment and sanity-check a quotation; do not hand its output to a loading crew as instructions.
Choosing between 20ft, 40ft and high cube
The decision is almost always volume against weight. A 40ft container gives roughly twice the volume of a 20ft but only a marginally higher payload — in many trades the 40ft payload is actually lower than the 20ft. That single fact drives most equipment choices in ocean freight.
As a rule of thumb, cargo denser than about 850 kg per CBM will hit the payload limit of a 20ft before filling it, which makes two 20ft units the sensible answer for heavy goods such as tiles, stone, machinery parts or liquids in drums. Light, bulky cargo — furniture, packaging, textiles, plastics — should go into a 40ft high cube, where the extra 300 mm of internal height adds roughly 9 CBM over a standard 40ft at little or no freight premium in most trades.
| Cargo density | Behaviour | Usual answer |
|---|---|---|
| Above ~850 kg/CBM | Weight-constrained: payload runs out with the box half full | 20ft GP, possibly multiple units |
| 400–850 kg/CBM | Balanced: volume and weight run out together | 40ft GP |
| Below ~400 kg/CBM | Volume-constrained: the box fills long before the payload | 40ft HC or 45ft HC |
| Below ~250 kg/CBM with under 13–15 CBM | Too little to justify a whole box | Consider LCL — check the W/M calculation first |
Verified Gross Mass and why your fit calculation feeds it
Under the SOLAS Convention, a packed container cannot be loaded onto a vessel unless the shipper has provided a Verified Gross Mass — the total weight of the cargo, packaging, dunnage and the container tare. VGM must be verified by weighing the packed container, or by weighing all the packages and adding the tare using a certified method; it may not simply be estimated.
The load calculation you do here is a planning figure, not a VGM. It is still useful evidence: if your planned gross weight and the weighbridge figure disagree by more than a small margin, something in the load is not what the packing list says it is, and it is far cheaper to discover that at the warehouse than at the terminal gate.
Container Load Calculator FAQ
Practical answers to the questions operators, forwarders and shippers ask most often about container carton fit calculator results.
How many CBM fit in a 20ft container?
The nominal internal capacity of a standard 20ft general-purpose container is about 33.2 CBM. A realistic floor-loaded carton stow reaches roughly 25–28 CBM once orientation losses, door clearance, dunnage and crush limits are taken into account. Palletised cargo typically achieves less again, because the pallet itself consumes about 140 mm of height per layer.
How many CBM fit in a 40ft and a 40ft high cube?
About 67.7 CBM for a standard 40ft and about 76.3 CBM for a 40ft high cube — the high cube's extra foot of external height adds roughly 8.6 CBM. Practical loads are usually 80–85% of those figures. The high cube is the better buy for light cargo in most trades because the freight differential over a standard 40ft is small relative to the extra volume.
Why is the payload of a 40ft container barely higher than a 20ft?
Maximum gross weight is set by the container's structural rating and by road and lifting limits, not by its length. A 20ft is rated at about 30,480 kg gross with a light tare, leaving roughly 28 tonnes of payload; a 40ft has nearly twice the tare and a similar gross rating, so its payload can be lower. This is why heavy cargo is shipped in 20ft units and light cargo in 40ft high cubes.
Does the calculator handle mixed carton sizes?
No. It models identical cartons in a single orientation, because that is the only case where a deterministic answer is meaningful. For a mixed-SKU load, run each carton group separately to understand how much space each consumes, add the volumes, and compare the total against usable capacity — then have the loading warehouse confirm the physical stow.
Should I use nominal capacity or 85% when quoting a customer?
Quote from the realistic figure, not the nominal one. Committing to 33 CBM in a 20ft and then discovering the load stops at 27 CBM is one of the more common ways a shipment ends up needing a second container at short notice, at spot rates. Nominal capacity is useful only for comparing equipment types against each other.
What is the difference between a 40ft high cube and a standard 40ft?
Height only. Both are 40 feet long and 8 feet wide externally; the high cube is 9 feet 6 inches tall against 8 feet 6 inches, giving roughly 300 mm more internal height and about 8.6 CBM more capacity. Note that the extra height matters for road transport — some routes, tunnels and low-bridge corridors restrict high cubes, and a few countries limit them on specific roads.
Can I load to the full internal height?
Rarely. The door aperture is roughly 110 mm lower than the internal ceiling, so the top tier usually has to be loaded before the doors are reached, or omitted entirely. You also need clearance for handling equipment, and the cargo's own crush rating often caps stack height well below the ceiling. Plan the top tier deliberately rather than assuming it.
How many pallets fit in a 20ft container?
Ten to eleven EUR pallets (1200 × 800 mm) or nine to ten industrial pallets (1200 × 1000 mm) in a single floor layer, depending on whether they are loaded straight or pinwheeled and whether slight overhang is acceptable. Double-stacking doubles the count if the pallet, the cargo and the internal height allow it — check the height of a loaded pallet against the 2.39 m internal height of a standard 20ft.
Does this calculator account for weight distribution?
No. It compares total cargo weight against total payload. Distribution is a separate and genuinely safety-critical question: cargo concentrated at one end of the container can be within total payload and still exceed axle limits on the road leg, or create an unsafe lift. A loading plan from the warehouse or a specialist stow tool is the right instrument for that.
What about refrigerated, open-top and flat-rack equipment?
The standard figures here describe dry containers. A reefer of the same nominal size holds materially less because the refrigeration unit occupies internal length and the T-floor and air-return path must stay clear. Open tops, flat racks and tanks have their own geometry and loading rules entirely. Enter custom internal dimensions if you are working with specialised equipment, and confirm the payload from the container's own CSC plate.
When should I switch from LCL to a full container?
The usual crossover in most trades is somewhere between 13 and 15 CBM, because LCL is charged per revenue ton and the per-unit rate stops being competitive once the volume approaches half a 20ft. The crossover moves with the trade lane, the season and the destination charges, which are often the deciding factor — run the LCL W/M calculation and compare the all-in landed cost rather than the ocean freight line alone.
Does GainingDocx check container utilisation against my documents?
The workspace reconciles what your documents claim. When a packing list, Bill of Lading and commercial invoice are grouped as one shipment, package counts, gross weights and CBM totals are compared across them, and a container whose declared load exceeds plausible capacity or payload is surfaced as a discrepancy for review.
Related tools, templates and guides
- CBM calculatorTotal the volume of every carton group before you choose equipment.
- LCL freight W/M calculatorCompare the cost of shipping loose against booking a full container.
- How to calculate CBM for shippingFormulas, unit conversions and the mistakes that distort a volume total.
- Container packing list templateAllocate packages and cargo lines to container and seal numbers with running totals.