What happened
Brent crude opened at 91.19 dollars a barrel on 19 August and rose 0.47 percent over the following twenty four hours to about 91.56 dollars. The move extends a rally that has been building through the summer, and it is a supply story rather than a demand one.
The immediate cause is the Strait of Hormuz, the narrow waterway between Iran and Oman through which a large share of the seaborne oil trade must pass. Renewed attacks on tankers transiting the strait in July reduced shipments, and the US Energy Information Administration now estimates that around 0.6 million barrels a day of production is shut in, with disruption expected to persist through the end of next year.
A second pressure point has opened further west. A fresh blockade threat against Saudi exports through the Bab el-Mandeb Strait, the entrance to the Red Sea, has raised the prospect of a second chokepoint being constricted at the same time as the first.
Layered on top is rising political tension between the United Arab Emirates and Iran, together with growing expectations among traders that Hormuz transits will remain restricted for an extended period. Rising demand for refined products has completed a distinctly bullish picture.
Why it matters
Oil sits at the base of almost every price in the economy. It moves goods, heats buildings, powers agriculture and forms the raw material for plastics, fertiliser and synthetic fabrics. When crude rises, the effect radiates outward into transport costs, food prices and manufacturing inputs over the following months.
For the United Kingdom the pain is doubled, because oil trades in dollars. A rise in the crude price combined with a softer pound means the sterling cost of a barrel climbs faster than the headline dollar figure suggests. That is the mechanism by which a distant shipping dispute reaches a British forecourt.
The timing is awkward. UK inflation has just risen to 2.9 percent on the back of higher energy bills, and the Bank of England expects a peak near 3.2 percent late this year. A sustained oil rally would make that forecast look optimistic and would strengthen the hand of the Monetary Policy Committee members already voting for higher rates.
There is a growth cost too. Higher energy prices act like a tax on households and businesses in oil importing countries, transferring income to producers. Money spent filling a tank is money not spent in shops, which is why oil shocks have historically preceded slowdowns.
Explained simply
The Strait of Hormuz is a two mile wide gap in a fence that a fifth of the world oil trade must squeeze through. Threaten the gap and the price rises everywhere, even where no barrel has actually gone missing.
Oil markets price risk, not just barrels. Traders are not only asking how much crude is available today but how much might be available in three months if a situation deteriorates. When a critical chokepoint is threatened, buyers pay more now to secure supply, and that premium shows up in the price long before any physical shortage appears.
The reason chokepoints matter so much is geography. Oil is produced in a handful of regions and consumed everywhere, and moving it means tankers travelling through a small number of narrow passages. Hormuz and Bab el-Mandeb are two of the most important. There are alternative pipeline routes, but their capacity is limited and their cost is higher.
Supply is also slow to respond. A shut in oil field cannot be restarted overnight, and a new field takes years to develop. Demand is equally stubborn in the short run, because people still have to drive to work and factories still have to run. When both sides of the market are inflexible, small changes in volume produce large changes in price.
That inflexibility is why a shortfall of 0.6 million barrels a day, which is less than one percent of global supply, can move prices by many dollars a barrel. There is very little slack in the system to absorb it.
What it means for you
Expect forecourt prices to follow. UK petrol and diesel prices track crude with a lag of roughly two to four weeks, and the retail price also carries fuel duty and VAT, so the pass through is proportionally smaller than the crude move but real. Supermarket forecourts and apps that compare local prices routinely find differences of several pence a litre.
If you drive a great deal, the practical savings are unglamorous but genuine. Correct tyre pressure, removing roof boxes and steadier motorway speeds reduce consumption by more than most drivers expect. Over a year of heavy mileage these amount to considerably more than shopping around for the cheapest pump.
Household energy is a separate but connected market. UK bills are driven mainly by wholesale gas rather than oil, though the two markets are linked through contracts and through substitution in power generation. A prolonged oil rally raises the risk that the Ofgem cap for the January period is set higher than currently expected.
For investors, energy shares often act as a partial hedge. A FTSE 100 tracker already carries meaningful exposure to large oil and gas producers, which tend to rise when crude does, so many UK savers hold this hedge without realising it. Deliberately concentrating in energy is a different and considerably riskier decision.
The bigger picture
Every serious inflation episode of the past fifty years has had an energy component, from the oil embargoes of the 1970s to the gas shock that followed the invasion of Ukraine. Energy prices are the fastest route from a geopolitical event to a household budget, which is why central bankers watch chokepoints as closely as they watch wage data.
What has changed is resilience. American shale production, larger strategic reserves and a growing share of electricity generated without fossil fuels mean the same disruption produces a smaller shock than it would have done two decades ago. Prices near 92 dollars are elevated but nowhere near the levels of 2008 or 2022 in real terms.
The variable to watch is duration. A brief disruption is absorbed; one that persists for a year forces refiners, shippers and governments to rebuild routes and inventories at permanently higher cost. The EIA assumption of continued shut in supply through the end of next year suggests officials are planning for the longer version.
