Air freight vs sea freight comes down to the familiar trade-off: ocean is cheap and slow, air is fast and expensive. Both statements are true, but neither one tells you whether a particular shipment belongs on a ship or a plane. For that you need to know how much cheaper and how much slower, and the answer starts with how each mode turns your cargo into a billable number.
Why the same cubic meter costs so much more by air
Ocean freight (called sea freight in the UK) and air freight don’t just charge different rates. They charge for different things.
- LCL ocean freight is billed per cubic meter (CBM) or per 1,000 kg, whichever is greater. A cubic meter of light cargo bills as one unit, the same as 1,000 kg of dense cargo.
- Air freight is billed on chargeable weight: the higher of actual weight and volumetric weight, which is length × width × height in cm ÷ 6,000. The 6,000 divisor is the general rule set out by IATA. One cubic meter therefore bills as at least 166.67 kg, usually written as about 167 kg.
- Express services use a smaller divisor, ÷ 5,000. A smaller divisor produces a bigger volumetric weight, so one cubic meter bills as at least 200 kg.
That conversion is the part of the comparison you can rely on. Ocean treats a cubic meter as the equivalent of 1,000 kg, air treats it as about 167 kg, and 1,000 ÷ 166.67 gives a fixed 6-to-1 ratio.
Rates are a different story. Using illustrative rates of $60–150 per CBM all-in for LCL and $3–8 per kg for air, and assuming $100 for the ocean side, a cubic meter of light cargo costs about $100 by sea against roughly $500–1,300 by air (167 kg × $3–8). That puts air at about 5 to 13 times the ocean price. Take the whole ocean range instead of a single $100 figure and the multiple spreads wider still. Both rates also move with season and capacity, and public freight rate indexes such as the Freightos Baltic Index (FBX), which publishes daily and weekly readings across 12 lanes, show how far ocean rates can swing.
To see what your own cargo bills as in each mode, run it through the chargeable weight calculator. For the full mechanics of actual versus volumetric weight, read chargeable weight explained.
Worked example: 100 boxes by ocean, air and express
Suppose you’re shipping 100 boxes, each 60 x 40 x 40 cm and weighing 8 kg.
- Total volume: 60 x 40 x 40 x 100 = 9,600,000 cm³ = 9.6 CBM
- Actual weight: 100 x 8 kg = 800 kg
- Density: 800 ÷ 9.6 ≈ 83.3 kg per cubic meter, about half of the 167 kg point where air stops charging for volume
Here’s what each mode bills:
- LCL ocean: the cargo weighs 800 kg but measures 9.6 CBM, which counts as 9,600 kg, so volume sets the bill: 9.6 CBM. Check the ocean result.
- Air: 9,600,000 ÷ 6,000 = 1,600 kg chargeable, double the actual weight. Check the air result.
- Express: 9,600,000 ÷ 5,000 = 1,920 kg chargeable. Check the express result.
At the same illustrative rates, the ocean freight comes to $580–1,440 (9.6 x $60–150) and the air freight to $4,800–12,800 (1,600 kg x $3–8). At the midpoints, $105 per CBM and $5.50 per kg, that’s $1,008 by sea against $8,800 by air, about 8.7 times, or roughly 9 to 1.
Density changes that gap. Once cargo is denser than about 167 kg per cubic meter, air bills on actual weight and the volume penalty disappears; for express the point is 200 kg per cubic meter. LCL keeps billing on volume all the way up to 1,000 kg per cubic meter. So the denser the cargo, the smaller the difference between the modes.
At the small end, the picture flips. LCL usually carries a minimum charge, commonly 1 CBM (it varies by forwarder and lane, and some regions set it at 3 CBM), and on top of that come handling fees at the origin and destination container freight stations (CFS), charged per shipment or per CBM. For a very small shipment those fixed costs dominate, and express or air can be cheaper door-to-door. Where exactly the lines cross depends on those fees and on your rates, so there is no single number to plan around.
Transit time: how many weeks does air actually save?
These are rough door-to-door ranges for shipments that hit no delays. They aren’t carrier schedules, so treat them as a planning guide only.
| Trade lane | Ocean (door-to-door) | Air (door-to-door) | Express |
|---|---|---|---|
| East Asia → US West Coast | 18–25 days | 3–6 days | 2–4 days |
| East Asia → US East Coast | 28–38 days | 4–7 days | 2–4 days |
| East Asia → Northern Europe | 32–42 days | 3–6 days | 2–4 days |
| Intra-Asia | 5–12 days | 1–3 days | 1–2 days |
On intercontinental lanes, then, ocean takes roughly 2 to 5 weeks longer: about 2–3 weeks to the US West Coast, 3–5 weeks to the East Coast and 4–5 weeks to Northern Europe. Air transit also depends on the service you book. UPS, for example, describes express air freight as 1–3 business days, standard as 3–5 and economy or consolidated service as 5–7 business days or more.
Real ocean shipments can run past the table. Port congestion (ships queuing for a berth), blank sailings (a carrier cancels a scheduled voyage) and customs inspections can each add a week or more. Air isn’t immune either: a customs hold can cost several days.
A few structural factors also add time to ocean freight:
- LCL consolidation. LCL cargo waits to be consolidated into a container at origin and is deconsolidated again at destination, so it takes longer than FCL. How much longer depends on the forwarder and lane. See FCL vs. LCL for how the two services work.
- Weekly sailings. Most main trade lanes (the regular port-to-port routes carriers serve) run a weekly service. Miss the cut-off time (the deadline for delivering cargo to the terminal) and you lose about 7 days waiting for the next vessel.
- Transshipment. Routings that change ships at a hub port make more port calls than a direct service.
If the arrival date matters, plan on the slow end of the ocean range plus about a week, and build that buffer into the date you place the purchase order, not into the arrival date you promise.
What the quoted rate leaves out
Neither mode’s quoted rate is the whole invoice.
- LCL ocean: on top of the ocean freight you’ll see origin handling, CFS fees, documentation and destination charges, billed per shipment or per CBM. Ask for an all-in quote, either door-to-door or delivered to the destination port, so the two modes are compared on the same basis.
- Air: carriers can re-weigh and re-measure your cargo. If their figures differ from what you declared, the chargeable weight on the invoice can change.
- Air surcharges: the fuel surcharge and the security surcharge (the airline’s per-kg charge for cargo security) are billed separately from the freight rate and updated by each airline on its own cycle. Korean Air, for instance, quotes its surcharges on shipments from Korea per kg, on a cycle that runs from the 16th of each month to the 15th of the next. Ocean has its own security charges, such as the ISPS surcharge tied to the ship and port security code; see freight surcharges explained.
- Express: a remote area surcharge (for deliveries outside the carrier’s regular service area) and a residential delivery fee can apply, and on a small parcel they make up a larger share of the bill.
The cost of time
Judged on freight cost alone, ocean wins almost every time. What it costs you is time, and time has a price:
- Inventory carrying cost. Stock sitting on a ship ties up cash. Assume a 20% annual cost of capital: 30 extra days in transit costs 20% × 30 ÷ 365 ≈ 1.6% of the cargo’s value.
- Obsolescence and seasonality. Products with a short selling window lose value while they wait.
- Stockout cost. Running out can cost more than the freight savings, whether that’s lost marketplace ranking or a penalty under a supply contract.
- Forecast risk. Shipping by sea means committing to a demand forecast earlier, by as much as the transit time gap of 2 to 5 weeks.
That’s why it often pays not to put everything on one mode. A common pattern is to move the forecast base volume by ocean and use air for the uncertain part and for launch-driven spikes. The global picture points the same way: according to IATA, air carries more than 33% of world trade by value but less than 1% by volume. In other words, air carries cargo with high value density ($/kg): goods worth a lot per kilogram.
Example: splitting a seasonal order between sea and air
Take an importer with 20 CBM of seasonal stock that needs to be on shelves by early November.
- Book in early September. 20 CBM is around or above the volume where FCL usually starts to pay off, so get an FCL quote alongside LCL (see FCL vs. LCL).
- Arrive by mid-October. That leaves about 2 weeks of buffer for delays.
- Split the order. Send 18 CBM by ocean and keep 2 CBM, about 10% of the order, as an optional air top-up if early sales run ahead of the forecast. If that cargo is light, the 2 CBM will bill as about 333 kg or more by air (2 × 166.67).
The ocean leg carries the bulk of the volume at the low rate, and you pay air rates only on the slice that actually needs speed.
Air freight or sea freight: quick decision guide
These are rules of thumb, not hard thresholds. Check them against real quotes.
- Cargo worth less than about $5 per kg: ocean.
- Cargo worth more than about $100 per kg, or a selling window under 6 weeks: air by default.
- Chargeable weight under about 150 kg: get an express quote as well.
- Density far below 167 kg per cubic meter: air’s volume penalty is at its steepest. See volumetric weight explained.
- Everything else: get all-in quotes for both modes and add the inventory carrying cost to the ocean side before comparing.
How much more expensive is air freight than sea freight?
For light, bulky cargo, air freight typically costs somewhere around 5 to 13 times more than LCL ocean freight per cubic meter. That range assumes an illustrative ocean rate of $100 per CBM against air rates of $3–8 per kg: one CBM bills as at least 167 kg by air, so it costs roughly $500–1,300 by air versus $100 by sea. Across the full range of ocean rates the multiple spreads even wider. The part that doesn’t move is the billing conversion: ocean treats 1 CBM as 1,000 kg, air treats it as about 167 kg, a fixed 6-to-1 ratio. Dense cargo narrows the gap because air then bills on actual weight.
How much longer does ocean freight take than air freight?
On intercontinental trade lanes, ocean freight usually takes about 2 to 5 weeks longer than air freight door-to-door. As a rough, no-delay guide, East Asia to the US West Coast runs about 18–25 days by sea against 3–6 days by air, and East Asia to Northern Europe about 32–42 days by sea against 3–6 by air. These are ballpark ranges rather than carrier schedules, and port congestion, blank sailings or customs inspections can each add a week or more to the ocean leg.
How is LCL ocean freight charged?
LCL ocean freight is charged per cubic meter or per 1,000 kg, whichever is greater. A shipment of 9.6 CBM weighing 800 kg, for example, is billed on its 9.6 CBM, because 800 kg is less than the 9,600 kg that its volume represents. Light, bulky cargo is billed on volume and dense cargo on weight, and the break point is a density of 1,000 kg per cubic meter. Most LCL quotes also carry a minimum charge, commonly 1 CBM, though the minimum varies by forwarder, lane and service.
When is air freight cheaper than sea freight?
Air or express can come out cheaper door-to-door when the shipment is very small. LCL carries a minimum charge, commonly 1 CBM, plus per-shipment handling fees at the origin and destination container freight stations, so a small box pays for far more than its size. There is no single size where this happens, because it depends on those fixed fees and on the rates you are quoted. For small shipments, get all-in quotes for both modes before you decide.
When should I use air freight?
Air freight makes sense when the cargo is valuable for its weight or the selling window is short. As a rule of thumb, goods worth more than about $100 per kg, or products with a selling window under 6 weeks, usually justify air, while goods worth under about $5 per kg usually belong on the ocean. Air also earns its cost when a stockout (running out of stock) would cost you marketplace ranking or a contract penalty. Low-density cargo, far below 167 kg per cubic meter, is where air carries its steepest volume penalty.
How long does air freight take?
Door-to-door air freight on major intercontinental lanes typically takes about 3 to 7 days, and express services about 2 to 4 days, assuming no delays. Transit also depends on the service level you book: UPS describes express air freight as 1–3 business days, standard as 3–5 business days, and economy or consolidated service as 5–7 business days or more. A customs hold can add several days.
What does air freight cost per kg?
This guide uses an illustrative range of $3–8 per kg for air freight, which is an example for comparison rather than a market rate. Real rates move with season and aircraft capacity, and the fuel surcharge and security surcharge are usually billed as separate per-kg lines that each airline updates on its own schedule. Also remember the rate applies to chargeable weight, so light cargo pays for at least 167 kg per cubic meter.
Can I split a shipment between sea and air?
Yes, and it’s a common approach. Put the volume you can forecast with confidence on ocean freight and hold back the uncertain part, or a launch spike, for air. For example, a seasonal importer with 20 CBM might ship 18 CBM by sea and keep 2 CBM, about 10% of the order, as an optional air top-up once early sales are clear. You pay air rates only on the slice that actually needs speed.