B Worked examples
1 · Mixed carton sizes in centimetres
10 cartons of 60 × 40 × 30 cm at 12 kg, plus 6 cartons of 45 × 35 × 25 cm at 8 kg.
- Line 1: 60 × 40 × 30 ÷ 1,000,000 = 0.072 m³ × 10 = 0.720 m³, 120 kg
- Line 2: 45 × 35 × 25 ÷ 1,000,000 = 0.039375 m³ × 6 = 0.236 m³, 48 kg
- Total: 0.956 m³ (33.77 ft³), 168 kg gross
- Sea W/M: 0.956 m³ against 0.168 t, so you pay on 0.956 W/M (volume governs; many LCL tariffs have a 1 W/M minimum)
- Air at ÷6,000: 956,250 cm³ ÷ 6,000 = 159.38 kg, lower than 168 kg, so 168 kg is chargeable
- Courier at ÷5,000: 956,250 ÷ 5,000 = 191.25 kg, now higher than gross — the divisor changes which figure wins
2 · Inches and pounds
10 cartons of 24 × 16 × 12 in, each 25 lb.
- One carton: 24 × 16 × 12 = 4,608 in³ ÷ 61,023.74 = 0.07551 m³ (4,608 ÷ 1,728 = 2.667 ft³)
- Total: 0.755 m³, 26.67 ft³
- Gross: 250 lb × 0.45359237 = 113.40 kg
- Air at ÷6,000: 755,116 cm³ ÷ 6,000 = 125.85 kg (277.46 lb), above gross, so volume governs
3 · Heavy crates where weight governs
2 crates of 1,200 × 1,000 × 1,000 mm, each 3,000 lb.
- Volume: 1.2 × 1.0 × 1.0 m × 2 = 2.400 m³
- Gross: 6,000 lb = 2,721.55 kg = 2.722 t
- Sea W/M: 2.722 t is larger than 2.400 m³, so the charge is on 2.722 W/M
4 · How many 50 × 40 × 30 cm cartons fit?
Each carton is 0.06 m³. Dividing usable volume at 85% fill gives the optimistic volume answer; stacking one carton size in its best orientation gives a more physical one.
| Container | Usable at 85% | Volume ≈ | Simple stack |
|---|
| 20' GP | 28.2 m³ | 470 | 392 (14 × 4 × 7) |
| 40' GP | 57.6 m³ | 959 | 840 (24 × 5 × 7) |
| 40' HQ | 64.9 m³ | 1,081 | 1,050 (30 × 7 × 5) |
The gap is why a volume figure should be read as a ceiling, not a promise. Ask your forwarder for a load plan before you commit to a carton count on a purchase order.
C CBM to cubic feet and billable kg
The "kg per CBM" figure is a pricing convention, not the real weight of your goods. It tells you the weight at which a carrier switches from charging on volume to charging on weight.
| CBM | ft³ | Sea W/M (1,000 kg) | Air ÷6,000 | Courier ÷5,000 | Road ÷3,000 |
|---|
| 0.1 | 3.53 | 100 kg | 16.67 kg | 20 kg | 33.33 kg |
| 0.5 | 17.66 | 500 kg | 83.33 kg | 100 kg | 166.67 kg |
| 1 | 35.31 | 1,000 kg | 166.67 kg | 200 kg | 333.33 kg |
| 2 | 70.63 | 2,000 kg | 333.33 kg | 400 kg | 666.67 kg |
| 5 | 176.57 | 5,000 kg | 833.33 kg | 1,000 kg | 1,666.67 kg |
| 10 | 353.15 | 10,000 kg | 1,666.67 kg | 2,000 kg | 3,333.33 kg |
Road divisors vary more than air or sea: European groupage often uses about 333 kg per m³, but loading-metre pricing is also common. Check the tariff.
D Container internal sizes used here
Full data sheet: Shipping container dimensions & capacity covers ten types (20' and 40' GP, 40' and 45' HC, reefers, open tops and flat racks) with door sizes, tare, max gross and payload, each cited to carrier and lessor spec pages, plus pallet counts and a CSV.
Figures below are representative of steel dry containers and are what the estimate uses. Your actual box can differ by a few centimetres and several hundred kilograms depending on owner, maker and age — the CSC plate on the door states its real limits.
| Type | Inside L × W × H | Door W × H | Inside volume | Usable at 85% | Max payload |
|---|
| 20' GP (standard dry) | 5,898 × 2,352 × 2,393 mm | 2,340 × 2,280 mm | 33.2 m³ · 1,172 ft³ | 28.2 m³ | ≈ 25,000 kg |
| 40' GP (standard dry) | 12,032 × 2,352 × 2,393 mm | 2,340 × 2,280 mm | 67.7 m³ · 2,392 ft³ | 57.6 m³ | ≈ 27,600 kg |
| 40' HQ (high cube) | 12,032 × 2,352 × 2,698 mm | 2,340 × 2,580 mm | 76.4 m³ · 2,696 ft³ | 64.9 m³ | ≈ 28,560 kg |
Why 85% by default? Hand-stacked cartons leave gaps at the walls, the roof and the door, and mixed sizes rarely tessellate. Common planning ranges are 80–85% for mixed cartons and up to about 90% for uniform cartons loaded by an experienced crew; palletised loads are often lower because of pallet footprints. Field 5 lets you pick 70–95%.
Weight can limit a container before volume does, especially in a 20' GP: 25 t of tiles fills only a fraction of the box. The estimate reports whichever limit needs more containers. Road weight limits in the origin and destination country may be lower than the container's own payload.
E Which volumetric divisor?
| Divisor (cm³/kg) | kg per m³ | Where you usually see it |
|---|
| 6,000 | 166.67 | Air cargo under the IATA standard; equivalent to 366 in³/kg or 166 in³/lb |
| 5,000 | 200 | International express and courier services; roughly the 139 in³/lb factor (≈ 5,022 cm³/kg) used in US parcel pricing |
| 4,000 | 250 | Some postal, regional and e-commerce parcel services |
| 3,000 | 333.33 | Road groupage and some domestic trucking tariffs |
Volumetric weight = length × width × height in cm ÷ divisor. Chargeable weight is the greater of that and the actual gross weight. Carriers round too: dimensions are often rounded up to the next whole centimetre or inch, and weights up to the next 0.5 kg or whole pound, sometimes per piece. This tool shows unrounded figures so you can see the margin.
F Questions
How do I calculate CBM for cartons of different sizes?
Put each size on its own line. Each line is L × W × H ÷ 1,000,000 (in cm) times its carton count; the shipment total is the sum of the lines. That is exactly what the worksheet above does, and the CSV export shows the per-line figures so you can check them.
How do I calculate CBM from inches or feet?
Inches: L × W × H ÷ 61,023.74. Feet: L × W × H ÷ 35.3147. Or choose in or ft in field 1 and type the measurements directly.
How many CBM fit in a 20ft, 40ft and 40ft high cube?
Inside volumes are about 33.2, 67.7 and 76.4 m³. Plan on roughly 28, 57 and 65 m³ of cartons at 85% fill, less if the cargo is palletised or fragile.
Does the calculator tell me exactly how many cartons fit?
No. It gives two bounds per carton size — a volume estimate and a simple single-orientation stack — and checks whether the carton passes the door. A real loading plan also considers mixed sizes, pallets, crush strength, weight distribution and the order cartons come off the truck.
What does W/M mean in sea freight?
"Weight or measure". For LCL, 1 m³ is treated as 1,000 kg and the line charges on the larger of total m³ or gross tonnes. Many tariffs also have a minimum of 1 W/M.
Is 1 CBM equal to 1,000 kg?
Only as a sea-freight pricing rule. In air freight with a 6,000 divisor, 1 m³ is billed as 166.67 kg; with a courier's 5,000 divisor it is 200 kg. The actual weight depends entirely on what is inside.
Which divisor should I choose?
The one printed on your quote or rate card. If you have nothing yet, 6,000 for airline cargo and 5,000 for express couriers are the usual starting points.
Should I measure the product or the carton?
The outer carton, as it will be handed over. Carriers measure at the widest point; a 60 × 40 × 30 cm carton that measures 61 × 41 × 31 cm after packing is almost 8% larger in volume.
Why do my totals show a dash?
A line is incomplete or invalid — for example a missing height or a quantity of 0. The message under the table names the line and field, and the field is outlined in red. Totals return as soon as it is fixed.
Is my shipment data stored or uploaded?
It is saved only in this browser's local storage so a refresh keeps your lines. It is never sent to a server. Use Start blank to clear it, or clear site data in your browser.