Container ships are sailing more slowly. File Image / Pixabay

Container ships are sailing more slowly amid high bunker prices, with carriers adjusting speeds across their networks to manage rising bunker fuel costs, according to sector specialist Alphaliner.

Between Q4 2025 and mid-April, average container ship speeds fell by 2.3%, from 15.58 knots to 15.22 knots, it said in an emailed report on Wednesday.

Most of the change came after late February, when Iran and US forces carried out attacks on Iran, with speeds slipping to 15.18 knots on April 14 - the lowest level since March 2023.

The timing tracks a sharp jump in fuel prices.

In Singapore, VLSFO hit $1,201/mt on March 13, while LSMGO reached $2,018/mt on April 3.

According to Ship & Bunker prices, Singapore’s VLSFO price has eased since the US and Iran announced a temporary ceasefire, with prices dropping to $764/mt on April 28.

With bunker fuel being one of the biggest voyage costs, cutting speed is one of the quickest ways for operators to limit the impact.

That has brought slow steaming back into focus, running ships at lower speeds to burn less fuel.

Even small reductions can make a noticeable difference to consumption.

The effect has not been the same everywhere. North-South routes slowed the most, with Far East-South America and Far East-ANZ both down 3.6%.

These longer voyages tend to have more room in the schedule to absorb slower sailing.

On the main East-West lanes, the reaction was also clear. Far East-US East Coast services cut speeds by 2.2%, Far East-US West Coast by 1.8%, and North Atlantic routes by 1.5%.

The Far East-Europe trade was the exception at first. Speeds rose by 1.3% as ships rerouted via the Cape of Good Hope and carriers pushed to keep schedules intact.

But since early March, this lane has also slowed, down 0.7% and now broadly in line with the rest of the fleet.