What is sweet crude oil?

Sweet crude oil is crude oil with a low sulfur content — conventionally less than 0.5% by weight. The name comes from the slightly sweet taste and smell that early oil workers noticed compared to high-sulfur 'sour' crude. Sweet crude is easier and cheaper to refine into petrol, diesel, and jet fuel, so it trades at a premium to sour grades.

What is the difference between sweet and sour crude?

The key difference is sulfur content. Sweet crude contains less than 0.5% sulfur; sour crude typically contains 0.5–3% or more. Higher sulfur requires additional processing steps (hydrodesulfurization) at the refinery to meet fuel-quality standards, adding cost. Most Middle Eastern and Canadian oil sands crude is sour; most North Sea and West African crude is sweet.

Is Brent crude sweet or sour?

Yes — Brent crude is classified as sweet (sulfur ~0.37%) and light (API gravity ~38°). It is one of the two main global benchmark grades alongside WTI (West Texas Intermediate), which is also sweet (sulfur ~0.24%) and slightly lighter (API gravity ~39.6°). Both benchmarks price the world's sweet crude trade.

Why does sweet crude cost more than sour crude?

Sweet crude costs more because it requires less refinery processing to produce high-value products like petrol, diesel, and jet fuel. Sour crude requires hydrodesulfurization units and generates more low-value residual products. The sweet-sour spread varies with refinery capacity: when complex refineries are plentiful, the premium narrows; when simple refineries dominate, it widens.

What API gravity is sweet crude?

Sweet crude is typically 'light' or 'medium' by API gravity — above 31.1° API is defined as light crude. WTI is ~39.6° API and Brent is ~38° API. Very light sweet crude (above 45° API) is called 'condensate' and is also low-sulfur but requires different handling. Heavy sour crude (e.g., Canadian oil sands, Venezuelan Orinoco) is below 20° API with 2–4% sulfur.

Sweet Crude Oil

Low-sulfur crude oil — the grade refiners prefer and markets price at a premium.

Definition

Sweet crude oil is crude petroleum with a sulfur content below 0.5% by weight. The term originated in the nineteenth century: oil prospectors would taste or smell a sample to distinguish low-sulfur crude (mildly sweet) from high-sulfur crude (harsh, pungent — called "sour"). Today the distinction is made by laboratory analysis, but the names persist.

The two most widely quoted global oil benchmarks — Brent crude (North Sea) and WTI (West Texas Intermediate) — are both sweet. Brent has sulfur of approximately 0.37%; WTI is even sweeter at approximately 0.24%. When you see an oil price on a financial news ticker, it is almost certainly the price of a sweet benchmark grade.

API gravity: light, medium, and heavy crude

Crude oil is classified by two independent properties: sulfur content (sweet vs sour) and density, expressed as API gravity (American Petroleum Institute scale). Higher API gravity = less dense = lighter crude.

Classification	API gravity	Examples
Very light / condensate	above 45°	Eagle Ford condensate (US)
Light crude	31.1°–45°	WTI (~39.6°), Brent (~38°), Bonny Light (Nigeria ~35°)
Medium crude	22.3°–31.1°	Arab Medium (Saudi Arabia ~31°), Kirkuk (Iraq ~36°)
Heavy crude	10°–22.3°	Arab Heavy (~27°), Merey (Venezuela ~16°)
Extra-heavy / bitumen	below 10°	Canadian oil sands (~8–10°)

Sweet crude is predominantly light or medium. The combination of low sulfur and high API gravity (light sweet crude) is the most valuable crude category because it yields the highest proportion of petrol and distillates with the least processing.

Sweet vs sour crude: key differences

Property	Sweet crude	Sour crude
Sulfur content	Below 0.5%	0.5% or above (often 1–3%)
Refining complexity	Simpler — less desulfurization needed	Requires hydrodesulfurization (HDS) units
Yield of high-value products	Higher (more petrol, diesel, jet fuel)	Lower (more residual fuel oil)
Price	Premium (typically $2–$5/bbl above sour)	Discount to sweet benchmarks
Key producers	Norway, UK, Nigeria, US, Angola	Saudi Arabia, Kuwait, UAE, Russia, Canada
Main benchmarks	Brent, WTI	Dubai/Oman, Urals, Western Canadian Select

The premium that sweet crude commands over sour is called the sweet-sour differential. It fluctuates with refinery configuration: regions with many complex refineries (equipped for sour processing) can narrow the differential by profitably running sour barrels; regions dominated by simple refineries must pay up for sweet grades. The US Gulf Coast, Rotterdam, and Singapore are complex refining hubs that habitually process significant sour crude volumes.

Brent and WTI as sweet benchmarks

Brent crude is a blend of crude streams from several North Sea fields (Brent, Forties, Oseberg, Ekofisk, Troll — the "BFOET" basket). It serves as the benchmark for roughly two-thirds of global crude trade, particularly Atlantic Basin, African, and Middle Eastern crude sold into Europe and Asia. Brent's low sulfur and moderate API gravity make it representative of the light sweet crude that European refineries were historically configured to process.

WTI is the benchmark for North American crude, priced at Cushing, Oklahoma. It is slightly lighter and sweeter than Brent. WTI has historically traded at a premium to Brent but this relationship has varied with US pipeline infrastructure and export restrictions. Since the lifting of the US crude export ban in 2015, WTI has often traded near parity with or at a small discount to Brent.

Both benchmarks directly underpin the retail fuel prices tracked in the fuel price explorer. A rise in Brent or WTI feeds through to refinery input costs and then to pump prices — see what makes up the price at the pump for the full pass-through mechanism.

How sweet crude prices reach the pump

Refiners buy crude oil on the spot market or through term contracts priced at a differential to a benchmark (e.g., "Dated Brent + $1.50/bbl"). They process it into petrol, diesel, jet fuel, and other products. The crude cost typically accounts for 45–60% of a litre of petrol at the pump in low-tax markets, and a smaller share in high-tax markets. For current retail prices in over 100 countries, see the fuel price explorer. For a tax breakdown by country, see the guide to highest fuel tax countries.

Frequently asked questions

What is sweet crude oil? Sweet crude oil is crude oil with a sulfur content below 0.5% by weight. The name comes from its slightly sweet taste and smell compared to high-sulfur "sour" crude. Sweet crude is easier and cheaper to refine into petrol, diesel, and jet fuel, so it trades at a premium. Brent and WTI — the two main global price benchmarks — are both sweet crude grades.: Sweet crude oil is crude oil with a sulfur content below 0.5% by weight. The name comes from its slightly sweet taste and smell compared to high-sulfur "sour" crude. Sweet crude is easier and cheaper to refine into petrol, diesel, and jet fuel, so it trades at a premium. Brent and WTI — the two main global price benchmarks — are both sweet crude grades.
What is the difference between sweet and sour crude? The key difference is sulfur content. Sweet crude is below 0.5% sulfur; sour crude is 0.5% or above (often 1–3%). Higher sulfur requires additional hydrodesulfurization processing at the refinery, adding cost and lowering the yield of high-value products. Most North Sea and West African crude is sweet; most Middle Eastern, Russian, and Canadian oil sands crude is sour.: The key difference is sulfur content. Sweet crude is below 0.5% sulfur; sour crude is 0.5% or above (often 1–3%). Higher sulfur requires additional hydrodesulfurization processing at the refinery, adding cost and lowering the yield of high-value products. Most North Sea and West African crude is sweet; most Middle Eastern, Russian, and Canadian oil sands crude is sour.
Is Brent crude sweet or sour? Brent crude is sweet — its sulfur content is approximately 0.37% and its API gravity is about 38°, classifying it as light sweet crude. WTI is also sweet (sulfur ~0.24%, API ~39.6°). Both are the primary benchmarks for global sweet crude pricing.: Brent crude is sweet — its sulfur content is approximately 0.37% and its API gravity is about 38°, classifying it as light sweet crude. WTI is also sweet (sulfur ~0.24%, API ~39.6°). Both are the primary benchmarks for global sweet crude pricing.
Why does sweet crude cost more than sour crude? Sweet crude requires less refinery processing to meet fuel-quality standards and yields more high-value petrol and diesel per barrel. Sour crude requires expensive hydrodesulfurization units and produces more low-value residual fuel oil. The sweet-sour price spread typically ranges from $2–$5 per barrel but widens when complex refinery capacity is scarce.: Sweet crude requires less refinery processing to meet fuel-quality standards and yields more high-value petrol and diesel per barrel. Sour crude requires expensive hydrodesulfurization units and produces more low-value residual fuel oil. The sweet-sour price spread typically ranges from $2–$5 per barrel but widens when complex refinery capacity is scarce.
What API gravity is sweet crude? API gravity and sulfur content are separate characteristics. Sweet crude can range from light (above 31° API, like Brent at 38° or WTI at 39.6°) to medium. Some medium-gravity crudes are also sweet. The highest-value category is "light sweet" — above 31° API and below 0.5% sulfur — which is what Brent and WTI represent.: API gravity and sulfur content are separate characteristics. Sweet crude can range from light (above 31° API, like Brent at 38° or WTI at 39.6°) to medium. Some medium-gravity crudes are also sweet. The highest-value category is "light sweet" — above 31° API and below 0.5% sulfur — which is what Brent and WTI represent.