Oil Crack Spreads Explained: Crude, Petrol, Diesel and Refining Margins

Oil Crack Spreads Explained: Crude, Petrol, Diesel and Refining Margins

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Learning objective

Learn what an oil crack spread measures, calculate a simplified 3:2:1 spread, distinguish product tightness from crude-price strength, and understand why the result is an indicator rather than a refinery's actual profit.

A refinery buys crude oil and converts it into petrol, diesel, jet fuel, liquefied gases and other products. A crack spread compares the market value of selected refined products with the cost of the crude input.

The term comes from “cracking”, a refining process that breaks large hydrocarbon molecules into smaller products. Traders use crack spreads to monitor refining economics and to hedge the relationship between crude and product prices.

Step 1: start with a single-product crack

A basic petrol crack can be expressed as:

Petrol crack = wholesale petrol price per barrel − crude price per barrel

Petroleum products such as US RBOB petrol futures are commonly quoted in dollars per gallon. Crude oil is quoted in dollars per barrel. Convert the units before subtracting:

Product price per barrel = product price per gallon × 42

If RBOB is $2.40 per gallon:

$2.40 × 42 = $100.80 per barrel

If the chosen crude benchmark is $80 per barrel, the simplified petrol crack is:

$100.80 − $80.00 = $20.80 per barrel

The result is a gross price difference. It does not deduct refinery fuel, labour, maintenance, transport, financing or compliance costs.

Step 2: calculate the 3:2:1 crack spread

The common 3:2:1 approximation assumes three barrels of crude produce two barrels of petrol and one barrel of distillate.

3:2:1 crack per barrel of crude = [(2 × petrol value per barrel) + distillate value per barrel − (3 × crude price per barrel)] ÷ 3

The US Energy Information Administration describes the ratio as a simplified representation of a typical US refinery's output. Actual yields vary by refinery, crude quality, operating configuration and product specifications.

Worked example

Assume same-month market prices of:

• crude oil: $80.00 per barrel;
• RBOB petrol: $2.40 per gallon;
• ULSD/distillate: $2.70 per gallon.

First convert the product prices:

• petrol: $2.40 × 42 = $100.80 per barrel;
• distillate: $2.70 × 42 = $113.40 per barrel.

Then calculate the product value from three barrels of crude:

(2 × $100.80) + $113.40 = $315.00

Subtract the crude input:

$315.00 − (3 × $80.00) = $75.00

Divide by three barrels:

$75.00 ÷ 3 = $25.00 per barrel

The simplified 3:2:1 crack is $25 per barrel of crude before other costs and revenues.

If crude rises to $90 while both product prices remain unchanged:

[$315.00 − (3 × $90.00)] ÷ 3 = $15.00 per barrel

The crack narrows even though crude becomes more expensive. A rising oil price does not automatically mean stronger refinery economics.

Step 3: match location, quality and month

A useful crack compares prices that represent a plausible refining system. Check:

• location: New York Harbor, US Gulf Coast, Northwest Europe or Singapore;
• crude benchmark: WTI, Brent, Light Louisiana Sweet or another grade;
• product: RBOB petrol, ULSD, gasoil or jet fuel;
• contract month: all legs should represent aligned delivery periods;
• currency and units: dollars per barrel, dollars per gallon or tonnes;
• specification: sulphur, vapour pressure and other quality rules.

Subtracting Gulf Coast petrol from a different-location crude contract can introduce transport and basis effects. Comparing front-month petrol with next-month crude mixes seasonality and calendar spreads into the calculation.

Step 4: distinguish a crack spread from accounting margin

Crack spreads omit much of a refinery's economics. Actual profitability can depend on:

• crude quality and price differentials;
• energy used by the refinery;
• labour and maintenance;
• catalyst and chemical costs;
• transport, storage and insurance;
• product yield beyond petrol and distillate;
• carbon, renewable-fuel and environmental compliance;
• downtime and utilisation rate;
• hedges, inventory valuation and foreign exchange;
• depreciation, interest and tax.

A refinery with a high headline crack can still report weak earnings if it suffers an outage or pays unusually high operating and compliance costs.

Step 5: understand what widens the spread

A crack can widen because product prices rise faster than crude, or because crude falls faster than products.

Potential drivers include:

• refinery outages and maintenance;
• low petrol or distillate inventories;
• stronger driving, freight, aviation or heating demand;
• product-export demand;
• pipeline, port or shipping constraints;
• seasonal fuel specification changes;
• sanctions or disruption affecting refining capacity;
• storm risk near refineries;
• a sudden change in crude quality discounts.

The EIA noted in September 2026 that tight global petrol supply and disruptions to refining activity had elevated US product crack spreads. It also observed that distillate cracks were stronger than petrol cracks because affected regions supplied large volumes of diesel and jet fuel.

That example shows why the product side must be analysed separately from the crude headline.

Step 6: understand what narrows the spread

The spread can narrow when:

• crude rallies but product prices lag;
• refineries return from maintenance;
• fuel demand disappoints;
• product inventories build;
• exports weaken;
• seasonal specifications become cheaper;
• new refining capacity increases supply;
• economic activity reduces freight or industrial fuel demand.

A negative single-product crack can occur temporarily when product value falls below the selected crude cost. A refinery does not necessarily shut immediately because it produces multiple products, has contractual commitments and faces start-up and shutdown costs.

Step 7: read petrol and distillate separately

The 3:2:1 blend can hide divergence.

Petrol demand often has a driving-season pattern. US RBOB specifications also change seasonally. Distillate demand is linked to freight, industry, agriculture and heating. Jet fuel has its own aviation cycle.

Track at least:

• petrol crack;
• distillate crack;
• combined 3:2:1 crack;
• crude calendar spread;
• regional product inventories;
• refinery utilisation and outage news.

A strong distillate crack alongside a weak petrol crack tells a different story from broad strength in both products.

Step 8: understand the hedge structure

A theoretical 3:2:1 futures hedge combines:

• long or short three crude units;
• the opposite exposure in two petrol units;
• the opposite exposure in one distillate unit.

Real contracts have different unit sizes. CME's RBOB contract represents 42,000 gallons, equal to 1,000 barrels. Traders must align contract quantities, months and signs correctly.

Execution creates several risks:

• one leg fills before another;
• margins change as volatility rises;
• basis differs from the refinery's physical crude and products;
• contract expiry and delivery rules differ;
• the operational yield is not exactly 3:2:1;
• futures gains and physical cash flows settle at different times.

This is a specialised commercial hedge, not a simple directional oil trade.

Step 9: avoid using cracks as an automatic crude signal

A widening crack can encourage refiners to process more crude, which may support crude demand. But the relationship is not mechanical. Maintenance, capacity limits, inventories, export economics and product demand all intervene.

Likewise, a narrow crack can reflect weak products rather than abundant crude. Analyse which leg moved and why.

Common mistakes

• Subtracting a per-barrel crude price from a per-gallon product price.
• Using 42 incorrectly or forgetting the final division by three.
• Mixing contract months or locations.
• Calling the crack a refinery's net profit.
• Assuming every refinery has a 3:2:1 yield.
• Ignoring other products, operating costs and compliance expenses.
• Looking only at the combined crack and missing petrol/distillate divergence.
• Treating a widening crack as guaranteed bullish evidence for crude.
• Ignoring contract size, margin and legging risk.
• Comparing spot and futures prices without labelling them.

Practical checklist

• Choose the refinery region and crude benchmark.
• Match crude and product delivery months.
• Convert every product quote to dollars per barrel.
• Calculate single-product and 3:2:1 cracks separately.
• Identify which leg caused the move.
• Check inventories, outages, utilisation and seasonal specifications.
• Separate gross price spread from operating profit.
• Review basis, contract size, expiry and margin rules.
• State whether prices are spot, futures, live or settlement.
• Define what evidence would invalidate the interpretation.

Sources

• US EIA: 3:2:1 crack-spread calculation
• US EIA: What drives product prices and crack spreads
• US EIA: Elevated crack spreads and petrol prices in 2026
• CME Group: RBOB petrol futures contract overview

This tutorial was prepared with AI-assisted research and writing under The Money Man editorial workflow. It is educational information, not personalised investment advice or a futures-trading recommendation. The worked prices and margin are hypothetical and exclude real-world costs.