# Benchmarking margins with crack spreads, dark spreads and clean spreads
A refinery in Rotterdam and a gas-fired power plant in Texas ask the exact same question every morning: "if I run flat out today, do I make money?" The answer is not the price of oil or gas alone. It is the *spread* between what the asset buys (feedstock) and what it sells (finished product). Traders call these crack spreads, dark spreads and clean spreads, and they are the single fastest way to judge whether an energy asset should be running or sitting idle.
Crude oil at $80 a barrel tells you nothing about whether a refinery is profitable. What matters is the margin between crude cost and the value of gasoline, diesel and jet fuel it produces. Same logic for power plants: the price of electricity alone doesn't tell you if a gas plant is making money, you need the gap between power price and fuel cost.
This is why traders, asset managers and utilities live by spread benchmarks. They strip out the noise of overall commodity price moves and isolate the actual processing margin, the thing the asset owner actually earns.
A crack spread is the difference between the price of crude oil and the price of the refined products "cracked" from it (gasoline, diesel, jet fuel), via the refining process that breaks (cracks) heavy hydrocarbon molecules into lighter ones.
The industry benchmark in the US is the 3:2:1 crack spread: 3 barrels of crude oil yield 2 barrels of gasoline and 1 barrel of diesel (a rough approximation of a real refinery's output mix). It's tracked daily using NYMEX (New York Mercantile Exchange) futures prices for WTI (West Texas Intermediate) crude, RBOB gasoline (Reformulated Blendstock for Oxygenate Blending), and ULSD (Ultra-Low Sulfur Diesel).
Worked example (illustrative, using round estimate prices for early 2026):
3:2:1 crack spread formula:
Crack spread ($/bbl) = [(2 × Gasoline price) + (1 × Diesel price) - (3 × Crude price)] / 3= [(2 × 96.60) + (1 × 107.10) - (3 × 75)] / 3
= [193.20 + 107.10 - 225] / 3
= 75.30 / 3
= $25.10/barrelThat $25/barrel (illustrative figure, not a live quote) is the rough gross margingross marginGross margin is the share of revenue left after subtracting the direct cost of producing goods or services, expressed as a percentage of revenue.View full definition → a refiner captures before fixed costs, labor and maintenance. US crack spreads have historically ranged from roughly $10 to over $50/barrel depending on refining capacity, seasonal demand and outages. Always check live values on the EIA (U.S. Energy Information Administration) petroleum data page rather than relying on remembered numbers, spreads move daily.
In Europe, the equivalent benchmark is often quoted against Brent crude and uses different product weightings depending on the refinery's configuration (a "gasoil crack" or "ARA" cracks referencing the Amsterdam-Rotterdam-Antwerp trading hub). European refiners generally run more diesel-heavy output than the US, since European vehicle fleets historically favored diesel.
Power generators use the same logic, adapted to electricity.
A dark spread is the margin a coal-fired power plant earns: the difference between the price of electricity it sells and the cost of coal it burns, adjusted for the plant's efficiency.
A clean spark spread (often shortened to "spark spread" for gas, "clean" spreads more broadly for the carbon-adjusted versions) does the same for gas plants, and critically includes the cost of carbon allowances.
Why "clean" matters: Under the EU Emissions Trading System (EU ETS) and the UK ETS, power plants must buy allowances for every ton of CO2 they emit. A "clean dark spread" or "clean spark spread" subtracts this carbon cost, giving the *true* margin. Ignoring carbon cost overstates profitability, sometimes dramatically.
Key concept: heat rate. This is the amount of fuel energy needed to produce one unit of electricity, expressed as a heat rate in MMBtu/MWh (million British thermal units per megawatt-hour) in the US, or as a plant efficiency percentage in Europe. A modern combined-cycle gas plant might have a heat rate around 6.5-7.0 MMBtu/MWh (roughly 50-55% efficiency); an older coal plant might be less efficient, needing more fuel per MWh produced.
Worked example: clean spark spread for a US gas plant (illustrative figures):
Fuel cost per MWh = Heat rate × Gas price
= 7.0 × $3.50 = $24.50/MWh
Spark spread = Power price - Fuel cost per MWh
= $40 - $24.50 = $15.50/MWhThat $15.50/MWh (illustrative) is the plant's gross margingross marginGross margin is the share of revenue left after subtracting the direct cost of producing goods or services, expressed as a percentage of revenue.View full definition → before fixed costs. If this were a European plant under EU ETS, you'd subtract carbon cost too:
Clean spark spread = Power price - Fuel cost - (Emission rate × Carbon price)With EU carbon allowances (EUAs, EU Allowances) trading in a range that has recently been roughly €60-90/tonne CO2 (estimate, check the ICE EUA futures data for current levels), a gas plant emitting roughly 0.35-0.40 tonnes CO2/MWh would see several euros per MWh shaved off its margin. This is precisely why European gas and coal plants dispatch differently than their US counterparts: carbon cost changes the merit order (the ranking of power plants by marginal cost, used by grid operators to decide which plants run first).
Knowledge check
1. Why do traders focus on crack, dark, or clean spreads rather than the outright price of crude oil or natural gas?
2. A refinery manager sees WTI crude prices rise sharply, while gasoline and diesel prices rise by roughly the same dollar amount. What is the most likely effect on the refinery's crack spread and run decision?
3. The 3:2:1 crack spread uses a ratio of 3 barrels of crude to 2 barrels of gasoline and 1 barrel of diesel. What is the primary purpose of this specific ratio?
4. Select ALL correct answers about what a spread benchmark (crack, dark, or clean spread) is designed to do.
Select all the correct answers.
5. Select ALL correct answers about why 'flat price' alone (e.g., the price of oil or gas) is insufficient to judge whether an energy asset is profitable to operate.
Select all the correct answers.
A few practical rules professionals use:
Positive spread, keep running. If the spread covers variable costs (fuel, variable O&M, and for power plants, carbon), the asset should operate. This is the essence of "merchant" dispatch decisions, made without a long-term contract, purely on today's market spread.
Spreads compress with new capacity. When many new gas plants or refineries come online, spreads shrink because the marginal (least efficient) plant needed to meet demand becomes more efficient, or excess supply chases the same demand. Watch capacity additions as a leading indicator.
Spreads are asset-specific. A given day's headline crack spread or spark spread is an average. Your specific refinery's or plant's actual margin depends on its real heat rate or yield, transport costs, and local price basis (the local price relative to the benchmark, e.g. a Gulf Coast refinery versus a Midwest one).
Negative spreads happen, and are normal. Plants and refineries do idle or run at minimum load during periods of negative or thin spreads. This is expected asset management, not distress, unless prolonged.
🎬 [VIDEO: "Crack Spreads Explained" - youtube.com - search for CME Group's official explainer on crack spread mechanics and how refiners hedge using futures]