Ocean vs. Air Freight: How Shipping Method Changes Your Landed Cost

The usual shorthand is that air is fast and ocean is cheap. That's true, and it's also where a lot of freight decisions stop, with the real numbers left unchecked.

When you weigh ocean vs. air freight, look at what each mode adds to your landed cost per unit. That depends on how the freight is priced, how long your cash sits in transit, and what a week of speed is worth to you. Here’s how to work it out for your own product.

How does shipping method change your landed cost?

Shipping method changes the freight line directly, changes your carrying cost and fees indirectly, and generally doesn't change your duty. Freight is the cost of moving the goods. Carrying cost is the cash tied up in inventory while it travels. Fees differ because ocean shipments carry container-specific charges such as port handling and drayage, which we cover in our post on the hidden costs that blow up a landed cost estimate.

Duty is the one that doesn't move. Under US customs valuation rules, transaction value generally excludes international freight and insurance, which the regulation calls C.I.F. charges (opens in new tab). Switching to air raises your freight line, not your dutiable value.

Confirm any edge cases, such as foreign inland freight, with your broker.

How is ocean freight priced?

Ocean freight is priced per container for a full container load (FCL), or by the revenue ton for a less-than-container load (LCL). A revenue ton is the greater of your volume in cubic meters or your weight in tons: 1 CBM is treated as 1 ton, or 1,000 kg. (opens in new tab) Light, bulky cargo is charged on volume, and heavy cargo is charged on weight.

For example, 3 CBM weighing 1,500 kg is charged as 3 revenue tons, because volume is the larger number. LCL also tends to carry per-shipment handling and documentation charges, which is why very small shipments cost more per unit than a full container does.

How is air freight priced?

Air freight is priced on chargeable weight, which is the greater of the shipment's actual weight and its volumetric weight. Volumetric weight is length × width × height in centimeters, divided by 6,000, a divisor Maersk describes as an IATA industry standard (opens in new tab), though some carriers use 5,000, which charges bulky shipments more.

Here's what that means in practice. A 50 cm cube works out to about 20.8 kg of volumetric weight, so a 5 kg box of contents is billed as 20.8 kg. Air punishes bulk in a way ocean doesn't, and that's why product shape matters as much as product value.

Why does your product's shape matter more than its price?

Compact, dense products carry a small air premium, and bulky, light products carry a huge one, because air bills on volume as well as weight. Here are two products, shipped both ways. The rates are illustrative assumptions, not quotes: air at $4.50 per kg, LCL at $120 per CBM plus $250 per shipment, and 3 extra weeks of carrying cost at an 8% annual cost of capital for ocean.

The compact product pays about a dollar more per unit to fly. The bulky product pays nearly its entire FOB price again, because 1,800 kg of actual weight gets billed as 4,000 kg. The same decision looks reasonable for one product and absurd for the other.

What does the extra transit time cost you?

Extra transit time costs you the cash and the selling days, and landed cost alone doesn't capture either. Your inventory is usually paid for before or as it ships, so every extra week in transit is a week that money isn't working. Sourcify's tariff guidance makes the related point that higher product value means more cash tied up in stock (opens in new tab).

How much longer depends on the lane. One freight forwarder estimates door-to-door transit from China to the US West Coast at 20 to 28 days by ocean and 5 to 8 by air (opens in new tab), and 32 to 40 days versus 6 to 9 to the East Coast. That forwarder sells these services and notes rates and times change, so treat the ranges as a starting point and confirm with a quote.

The carrying cost in the table above is small, around $0.04 per unit, because three weeks of capital on a $9.00 item isn't much. The bigger cost of ocean is usually a stockout, and that doesn't appear in landed cost at all.

When does air freight make sense?

Air makes sense when the premium per unit is smaller than what the speed earns you. A simple test is to divide the air premium by your contribution margin per unit. That gives you the share of units air has to save from a stockout to pay for itself.

In the example, assume the compact product earns $20 of contribution margin per unit. The $0.96 premium means air pays off if it saves about 5% of units from a stockout. The bulky product earns $15 per unit, and the $7.40 premium means air would need to save about half of them. That's a launch-week decision at best.

Air usually fits dense, high-value, or urgent goods, new product launches, and top-up shipments to cover a gap. Ocean fits steady, forecastable demand and bulky goods. Many brands combine them: ocean for the base order, air for the units they can't afford to be out of.

How do you put freight into your landed cost estimate?

Get a freight quote for each mode, divide it by the units in the shipment, and run each one through your landed cost estimate as a separate scenario. The calculator's freight input is a per-unit number, so the work is the division. A $5,625 air shipment of 5,000 units is $1.125 per unit.

Run the calculator once per mode with everything else held constant, then compare. The calculator doesn't have a transit-time field, so if you want to include carrying cost, add it to the other fees line. Keep a note of the transit days next to each result, since the decision comes down to cost against time.

Common questions about ocean vs. air freight

Is air freight always more expensive than ocean freight? Per unit, usually yes, but the gap depends on your product's weight, volume, and shipment size. Dense, compact products can carry a small premium, while bulky, light products can cost several times more by air.

Does air freight increase my import duty? Generally no. In the US, transaction value for duty purposes excludes international freight and insurance, so the mode you ship by doesn't change your dutiable value. Confirm specifics with your customs broker.

How do I calculate volumetric weight for air freight? Multiply length, width, and height in centimeters and divide by 6,000. If the result is greater than the actual weight, you're billed on the volumetric weight.

Run both modes through your numbers

Get an ocean quote and an air quote for your next order, divide each by your unit count, and enter both into Izba's landed cost calculator one at a time. Compare the landed cost per unit, then decide whether the speed is worth the difference.