How Conflict Reaches the Shelf

A conflict far from a shopping aisle can still change what is on it. The route is not mysterious, but it is long, and each link has its own delay and its own size. We set out the chain, the latest figures we could verify, and the arithmetic a reader can repeat.

The chain from a strait to a shelf

We think of a handful of narrow passages as the pressure points of sea trade. When a passage becomes unsafe, ships either wait, pay more for insurance and fuel, or take a longer route. Each choice raises the cost of moving a unit of cargo. We expect longer voyages to tie up ships, leaving fewer available elsewhere, which is one way rates can rise on routes far from the conflict.

Energy matters in a different way. The US Energy Information Administration reported that oil flows through the Strait of Hormuz were 20.9 million barrels per day in 2023, about 20% of global petroleum liquids consumption, and that about one fifth of global liquefied natural gas trade passed through it. Fuel is an input to ships, factories, farms and trucks, so an energy shock reaches many prices at once.

What the 2026 figures show

The United Nations Trade and Development agency (UNCTAD) assessed on 1 April 2026 that daily Hormuz transits fell from about 130 ships in February to 6 in March, a drop of about 95%, after escalation on 28 February. It projected merchandise trade growth of 1.5% to 2.5% in 2026, down from about 4.7% in 2025. Reporting on the same assessment put tanker rates, indexed to 100 on 27 February, at 188 for dirty tankers and 215 for clean tankers by late March.

Container shipping tells a quieter story. Drewry's World Container Index stood at $4,485 per 40 foot container on 15 October 2026, up 3% on the week after three weekly declines. Shanghai to Rotterdam was $3,522 and Shanghai to Los Angeles was $7,884. These are spot rates, which the index describes as a benchmark for index-linked contracts. The earlier Red Sea episode left a measurable mark: UNCTAD found in February 2024 that Suez Canal transits were down 42% from their peak and weekly container ship transits down 67%.

How much reaches the price

We think freight is often a small part of a product's price, so even a large rise in freight can move the final price only modestly. IMF economists estimated, using data from 143 countries over 30 years, that a doubling of freight rates raises inflation by about 0.7 percentage points. Import prices respond within about two months, while consumer prices build for roughly a year and the effect lasts up to 18 months.

The Federal Reserve Bank of Boston studied US import unit values from January 2016 to June 2024. A 1% rise in shipping costs raised those values by slightly more than 0.01% within one to three months. The link was stronger for goods that arrive by fewer routes, which suggests that products with limited alternatives feel disruption first.

A worked example

The numbers in this example are illustrative, not real data. Suppose a container holds 20,000 identical items that retail for $20 each, and freight for the container is $4,000.

Freight per item = Container freight / Items per container = $4,000 / 20,000 = $0.20, which is 1% of the retail price.

If freight doubles to $8,000, freight per item becomes $0.40. The rise of $0.20 is 1% of the $20 retail price. If the whole increase passes through once, with no change in margins, the shelf price rises by about 1%. We use pass-through to mean the change in the consumer price divided by the change in the cost, so full pass-through here equals 1.0 and partial pass-through is below it.

We think the useful lesson is proportion. A cheap, bulky product with freight at 5% of its price would move five times as much. A high value item would barely move.

What the evidence does not show

Spot rates are not necessarily what an importer pays, because contract terms can differ. Estimates from earlier shocks may not carry over, since the Boston study found small and statistically insignificant pass-through in 2016 to 2019. The authors also note that import unit values are not the aggregate import price index. We cannot yet say how much of any 2026 price change comes from freight, energy, tariffs or demand, and we would distrust anyone who claims to separate them cleanly this soon.

Going deeper

To read supply chain conditions directly, the New York Fed's Global Supply Chain Pressure Index draws on transportation and manufacturing data and is updated monthly on the fourth business day. Three formulas are worth keeping:

• Freight per unit = Container freight rate / Units per container
• Price effect (%) = Increase in freight per unit / Retail price per unit x 100
• Pass-through = Change in consumer price / Change in cost

Related terms worth looking up are landed cost and lead time, the delay between a cost change and its appearance in prices. We invite scrutiny of every figure above; each is linked to the page where we read it.