When a business tells me its domestic air freight bill has "gone through the roof", the cause is rarely the base rate. More often it is cubic weight on bulky cartons, a string of surcharges nobody noticed on the quote, or minimum charges on lots of small consignments. Once you understand how Australian carriers build a price, you can predict your invoices and control them.
This article explains each part of a domestic air freight charge, with worked examples. It forms part of our guide to optimising your business supply chain using domestic air freight.
The basic formula
Almost every domestic air freight charge in Australia follows the same structure:
Freight charge = chargeable weight × rate per kilo for the lane and service (or the minimum charge, whichever is higher)
Plus fuel surcharge, security and handling fees, and any accessorial charges for pick-up or delivery conditions
Plus GST at 10 per cent on domestic services
The two parts that cause the most confusion are chargeable weight and surcharges, so we will start there.
Chargeable weight: dead weight versus cubic weight
Aircraft run out of space before they run out of weight capacity when they carry light, bulky goods. To make sure a carton of pillows pays for the space it takes up, carriers charge on whichever is greater:
- Dead weight: what the consignment weighs on a scale, including packaging and pallets.
- Cubic (volumetric) weight: the volume of the consignment in cubic metres, multiplied by a conversion factor.
The higher figure becomes the chargeable weight. Qantas Freight explains its own calculation this way: a consignment's cubic weight is compared with its actual weight, and the base charge is worked out on whichever is higher.
Conversion factors used in Australia
This is where many businesses get caught out. Different carriers and services use different factors, so the same carton can have a different chargeable weight depending on who carries it.
| Conversion factor | Equivalent divisor (cm) | Where you will commonly see it |
|---|---|---|
| 167 kg per m³ | L × W × H ÷ 6,000 | The IATA standard for international air cargo |
| 200 kg per m³ | L × W × H ÷ 5,000 | Qantas Freight's published domestic example uses this ratio |
| 250 kg per m³ | L × W × H ÷ 4,000 | Many domestic express and courier networks, such as TNT Domestic Express |
| 333 kg per m³ | L × W × H ÷ 3,000 | Common for general road freight |
Always ask which factor applies to your account. A carrier quoting a lower rate per kilo with a higher conversion factor can end up more expensive for bulky goods.
A carton measures 60 cm × 40 cm × 40 cm and weighs 12 kg.
Volume = 0.6 × 0.4 × 0.4 = 0.096 m³
At 167 kg/m³: 0.096 × 167 = 16.0 kg chargeable
At 200 kg/m³: 0.096 × 200 = 19.2 kg chargeable
At 250 kg/m³: 0.096 × 250 = 24.0 kg chargeable
In every case the cubic weight is higher than the 12 kg dead weight, so you pay for between 16 and 24 kg. On a 250 kg/m³ network, you are paying for twice the carton's actual weight.
How to measure correctly
Carriers measure the outermost points of each piece as it is presented, including bulges, handles, strapping and pallet overhang. Round dimensions the way your carrier does (usually up to the nearest centimetre) and include the pallet in both weight and height. Most networks now use automated dimensioning equipment, and any difference between your declaration and their measurement will be re-invoiced, sometimes with an adjustment fee.
Rates per kilo, weight breaks and minimum charges
Carriers publish or negotiate a rate per kilo for each lane (for example, Melbourne to Perth) and each service level. Three features shape what you actually pay.
Weight breaks
Rates usually fall as chargeable weight rises. A carrier might charge one rate up to 25 kg, a lower rate from 25 to 100 kg, and lower again above that. Consolidating several small consignments into one larger one can move you into a cheaper break.
Minimum charges
Every consignment has a minimum charge, regardless of weight. If you send many small parcels, the minimum charge rather than the per-kilo rate may drive most of your spend. That is why satchel products and flat-rate parcel services exist for light items.
Service levels
The same lane can have several prices depending on speed and priority: standard air, express, priority or next-flight-out, and same-day or dedicated services. Priority products cost more because they guarantee space on a specific flight rather than the next available one.
Surcharges and extra fees to expect
Surcharges are where quotes and invoices most often differ. Ask for a full list before you sign, and check which apply automatically.
- Fuel surcharge. Most carriers apply a fuel levy, usually a percentage of the freight charge, reviewed regularly in line with jet fuel or diesel prices. Fuel prices have been volatile through 2026, so check how often your carrier adjusts the levy and where it is published.
- Security screening. Under Australia's aviation security rules, air cargo must be examined or come from a Known Consignor before loading. Freight lodged with a valid Consignment Security Declaration moves straight through. Unscreened freight may be screened at the terminal for a per-piece or per-kilo fee, and you may need to lodge earlier.
- Dangerous goods handling. Declared dangerous goods attract acceptance checks and extra fees, and some can only travel on cargo aircraft.
- Oversize and heavy pieces. Items above a carrier's standard dimension or weight limits for manual handling attract surcharges or must go on a different service.
- Pick-up and delivery conditions. After-hours, weekend, residential, tail-lift, hand-unload and timed deliveries often cost extra.
- Regional and remote area surcharges. Deliveries beyond a carrier's metropolitan zones usually carry an extra charge, and some areas are serviced through agents.
- Adjustments. Re-weigh and re-measure corrections, address corrections and futile pick-up or delivery fees.
When comparing providers, give each one the same consignment profile: dimensions, weights, lanes, service level and delivery conditions. Ask them to show the conversion factor and every surcharge. Our guide on how to choose a domestic air freight provider lists the questions to ask.
A complete worked example
Two cartons, each 60 × 40 × 40 cm and 12 kg. Carrier uses 250 kg/m³.
Total volume 0.192 m³ × 250 = 48 kg cubic. Dead weight 24 kg. Chargeable weight: 48 kg.
Illustrative rate: $4.20 per kg for the 25–100 kg break. Freight: 48 × $4.20 = $201.60
Illustrative fuel surcharge at 15%: $30.24
Residential delivery fee: $8.00
Subtotal: $239.84. Plus GST: $23.98. Total: $263.82
If the same goods were packed into cartons measuring 50 × 40 × 35 cm, the cubic weight would fall to 35 kg, and the freight charge would drop by more than a quarter before surcharges.
These rates are illustrative only. Real rates vary widely between carriers, lanes, volumes and contract terms.
How to reduce what you pay
- Cut cubic volume first. Right-sizing cartons usually saves more than rate negotiation. Our guide to packaging goods for domestic air freight shows how.
- Know your chargeable weight profile. Pull three months of invoices and calculate how much of your spend is driven by cubic weight versus dead weight. This tells you where to focus.
- Consolidate. Combine consignments to the same destination to reach better weight breaks and avoid repeated minimum charges.
- Pre-screen your freight. Lodge through a Regulated Air Cargo Agent or become a Known Consignor if your volumes justify it, so you avoid terminal screening fees and delays.
- Match service level to need. Not every consignment needs priority. Use standard air where next-day is enough, and road where it is not needed at all. Our comparison of domestic air freight versus road freight helps with that decision.
- Negotiate on your real profile. Carriers price accounts on volume, density, lanes and consistency. Businesses that can show steady, well-packed freight are in a strong position.
- Plan around peak season. Capacity tightens and peak surcharges can appear in the lead-up to Christmas. See our peak season planning guide.
Checking your invoices
Build a simple monthly check. Compare declared and invoiced dimensions for each consignment, flag re-measure adjustments, and confirm the fuel surcharge percentage matches the carrier's published rate for that period. Repeated adjustments usually point to a packing or data problem at your dispatch bench, which is cheaper to fix than to keep paying for.
Understanding rates is the foundation of any air freight strategy. For the bigger picture on where air fits in your logistics, read our complete guide to domestic air freight for business supply chains.
Frequently asked questions
What is chargeable weight in domestic air freight?
Chargeable weight is the weight a carrier uses to calculate your freight charge. It is the greater of the consignment's actual weight and its cubic weight, which is calculated from its volume using the carrier's conversion factor.
Why do carriers use different cubic conversion factors?
Each carrier sets its factor based on the aircraft and vehicles it uses and how its network is priced. International air cargo commonly uses 167 kg per cubic metre, while many domestic express networks use 250 kg per cubic metre. Always confirm the factor on your account.
Is GST charged on domestic air freight?
Yes. Domestic freight services within Australia are generally subject to 10 per cent GST. International freight is usually GST-free, but this article covers domestic services only. Check with your accountant for your specific situation.
How can I avoid security screening fees?
Lodge your freight with a valid Consignment Security Declaration. You can do this by using a Regulated Air Cargo Agent that examines your freight, or by becoming an approved Known Consignor through the Department of Home Affairs if your volumes justify the investment in security procedures.
Sources and review. This article draws on guidance from the Civil Aviation Safety Authority (CASA), the Cyber and Infrastructure Security Centre within the Department of Home Affairs, IATA, airline cargo conditions of carriage and published carrier information. Rates, surcharges and rules change often, so confirm current requirements with your carrier before you ship.
Written and reviewed by
George Brown
Senior Air Freight Editor, Georgeiv.net
George has 18 years of air cargo experience, from ramp operations at Sydney Airport to managing airline allocations and pricing for forwarders across Australia and Asia-Pacific. He leads our domestic air freight coverage and checks every figure and rule before publication.