📊 Freight Density Calculator
Don't know CBM? Use the CBM calculator first.
What is freight density?
Freight density is the weight per unit of volume of your shipment, expressed in kilograms per cubic metre (kg/m³). It tells you whether your cargo is "heavy for its size" (high density) or "bulky for its weight" (low density).
Density matters because freight carriers price on the greater of weight or volume — high-density cargo gets charged on its weight; low-density cargo gets charged on its volume. If you know your density, you can predict which factor will dominate the freight bill and choose the best shipping mode accordingly.
Example: 600 kg occupying 2 CBM = 300 kg/m³
Density break-even points by mode
Each freight mode has a different volumetric divisor — meaning different break-even densities at which the chargeable basis flips from volume to weight.
| Mode | Break-even density | Notes |
|---|---|---|
| Airfreight (IATA) | 167 kg/m³ | Divisor 6,000 cm³/kg. Below 167, charged on volume; above, on weight |
| Courier / express (DHL, UPS, FedEx) | 200 kg/m³ | Divisor 5,000 cm³/kg. Stricter than airfreight |
| Some express (4,000 divisor) | 250 kg/m³ | Used by some domestic UK carriers for low-density goods |
| Sea freight LCL | 1,000 kg/m³ | 1 CBM = 1 tonne chargeable. Most cargoes are well below this so volume-based |
| European road groupage | 333 kg/m³ | Or charged per loading metre (LDM) — different metric |
What density tells you about mode choice
- Under 100 kg/m³ — Very bulky cargo (polystyrene, pillows, empty plastic items). Punished by every mode's volumetric pricing. Consider compressed packaging, vacuum-sealing, or shipping as nested/flat-pack
- 100–200 kg/m³ — Light goods (clothing, soft furnishings, plastic items). Volumetric in all modes including sea LCL. Sea LCL usually cheapest for non-time-critical
- 200–500 kg/m³ — Mid-density (most consumer goods, electronics, mixed cartons). Volumetric in sea LCL but weight-based in air. Sea LCL almost always cheapest non-urgent
- 500–1,000 kg/m³ — Dense cargo (books, hardware, machine parts). Approaching weight-based pricing in sea LCL. Sea LCL is very efficient at this density
- 1,000+ kg/m³ — Heavy cargo (steel, metal parts, dense machinery). Always weight-based in sea. Best per-kg rates available; FCL may be cheaper than LCL
- 3,000+ kg/m³ — Very dense (steel coils, ingots). Quickly maxes out container weight limits — may need a 20ft container that doesn't fill the space but reaches max payload
Worked examples
Example 1 — Bulky cargo (low density)
10 cartons of foam packaging insulation, total weight 80 kg, total volume 4 CBM:
- Density = 80 ÷ 4 = 20 kg/m³ — extremely bulky
- Airfreight chargeable: 4 CBM × 167 kg/m³ ÷ 1 (since divisor maps cm³ to kg) ≈ 668 kg volumetric. Expensive.
- Sea LCL chargeable: 4 CBM × 1,000 = 4,000 kg (i.e. 4 tonnes/CBM basis). Around 4 CBM charged.
- Recommendation: sea LCL — at 4 CBM you're well within LCL range; any airfreight rate would be brutal
Example 2 — Mid-density cargo
Electronics shipment, 1,200 kg in 3 CBM:
- Density = 1,200 ÷ 3 = 400 kg/m³
- Sea LCL volumetric: 3 CBM × 1,000 = 3,000 kg; actual = 1,200 kg → charged on 3 CBM (volumetric)
- Airfreight chargeable: vol = 3 m³ × 166.67 = ~500 kg; actual = 1,200 kg → charged on 1,200 kg (weight)
- Sea LCL approximate cost: 3 CBM × £60–£90 = £180–£270
- Airfreight approximate cost: 1,200 kg × £3.50/kg = £4,200
- Recommendation: sea LCL unless time-critical
Example 3 — Heavy dense cargo
Steel fittings, 4,000 kg in 1 CBM:
- Density = 4,000 ÷ 1 = 4,000 kg/m³ — extremely dense
- Sea LCL: charged on 4 tonnes (weight wins). Around £240–£360 typical
- Airfreight: charged on 4,000 kg. Around £8,000+
- Recommendation: sea, but consider whether a 20ft FCL ([£1,200–£1,800](roughly) for Asia–UK) is actually cheaper than LCL despite the empty space — at 4 tonnes you'd be using very little of the container's 28-tonne capacity but it might still win on per-tonne cost
Density and chargeable weight — the calculation in reverse
Knowing your density also lets you predict chargeable weight before booking. Multiply density by volume to get actual weight; compare to the volumetric weight (volume × the relevant break-even density per mode) — chargeable is the higher.
For example, at 250 kg/m³ density in airfreight (break-even 167), you're above break-even — so chargeable weight = actual weight. At 250 kg/m³ in courier (break-even 200), still above — chargeable = actual. At 150 kg/m³ in airfreight (below break-even 167), chargeable = volumetric, which will be higher than actual.
Related calculators & guides
- CBM Calculator — calculate volume first
- Volumetric weight guide — how chargeable weight works
- Chargeable weight calculator — air/courier
- Landed cost calculator — full UK landed cost
- Sea Freight A–Z · Airfreight A–Z