When oil companies report results, the headline price of crude gets most of the attention. But for many of them, some of the biggest swings in profit come from a less familiar number: the refining margin. It explains why an oil major can post a bumper quarter even when crude prices are not at their highs, and why petrol and diesel prices do not always follow oil.
What a refining margin is
A refinery buys crude oil and turns it into products people actually use, such as petrol, diesel, jet fuel and heating oil. The refining margin is the difference between what the refinery earns from selling those products and what it pays for the crude, usually measured in dollars per barrel.
Analysts often use a simple version called a crack spread. A common example is the 3-2-1 crack, which assumes three barrels of crude make two barrels of petrol and one of diesel. Real refineries are more complicated, and each company reports its own indicator margin, but the idea is the same.
Why margins swing so much
Refining margins depend on the balance between demand for fuels and the capacity available to make them. When refineries close, suffer outages or cannot get the crude they need, product supply tightens and margins widen. Wars and sanctions can disrupt both crude flows and fuel exports, which is why margins often jump during geopolitical crises.
Diesel is especially sensitive. It powers lorries, ships and farm machinery, and a lot of global supply has historically come from a handful of regions. When those flows are disrupted, diesel prices can rise much faster than crude.
Why it matters for traders
Oil majors such as Shell and BP have big refining and trading businesses alongside their oil and gas production. When refining margins are high, that downstream side can deliver a large share of profits. Traders watching results look at the reported refining margin to understand whether a strong quarter was driven by crude prices, by fuel margins or by both.
Margins also matter for consumers and inflation. When the gap between crude and fuel widens, pump prices can stay high even if oil falls, which feeds into transport costs and inflation data.
A simple example
Suppose crude costs $100 a barrel and the fuels a refinery makes from that barrel sell for a combined $125. The gross refining margin is $25. If a supply disruption pushes fuel prices up to $140 while crude stays at $100, the margin jumps to $40. That extra $15 a barrel, across millions of barrels, can transform a refiner’s quarterly profit.
Common mistakes
One mistake is assuming oil companies always profit most when crude is high. Integrated majors earn from several businesses, and refining can move the other way. Another is treating high margins as permanent. New capacity, demand falls or the end of a disruption can shrink them quickly. A third is ignoring the costs of running a refinery, which the headline margin leaves out.
The bottom line
Refining margins measure the gap between crude prices and fuel prices. They can swing sharply on outages and geopolitics, and they help explain bumper results at oil majors and stubborn pump prices. For the wider picture of how oil companies earn money, read our guide to upstream and downstream oil. To see how you would trade an energy results day, try the free Samuel & Co Trading Trader Assessment.
