Today, Wednesday August 12, 2026 (21 Mordad 1405), Brent crude is trading around 89 dollars a barrel and WTI around 83 dollars, a gap of nearly 6 dollars between two "crude oils" priced in the same global market at the same moment. This lesson explains where these three numbers, Brent, WTI, and the OPEC Reference Basket, come from, why they differ, and why their moves reach straight into Iran's state budget and its currency market.
What you will learn in this lesson
You will learn why crude oil is not one uniform commodity, what the three main oil benchmarks (Brent, WTI, and the OPEC basket) actually are, what drives the price gap between them, and how their swings travel into the government's budget, foreign exchange revenue, and ultimately the toman.
Definitions
Crude oil's chemical makeup varies by the field it comes from, so instead of a single "oil price," global markets rely on a handful of reference benchmarks against which every other crude is priced.
- Brent: a blend of crude from several North Sea fields, the reference benchmark for most oil trade in Europe, West Asia, Africa, and Asia. Based on the U.S. Energy Information Administration's (EIA) data on the global oil market, Brent is the world's most widely used benchmark for pricing crude exports.
- WTI (West Texas Intermediate): the North American benchmark, delivered at the storage hub in Cushing, Oklahoma. According to the EIA and Trading Economics, WTI is a "light, sweet" crude, meaning low density and low sulfur content.
- The OPEC Reference Basket (ORB): a weighted average of the export crude prices of the member countries of the Organization of the Petroleum Exporting Countries (OPEC), including Iran's own heavy crude. OPEC's secretariat calculates and publishes it every business day.
Why these three numbers are not the same
Two main factors push the price of any crude grade above or below the rest.
Quality. Two technical measures, API gravity (density; the higher the number, the "lighter" the crude) and sulfur content (the lower it is, the "sweeter" the crude), set the cost of refining it. As the EIA explains, light, sweet crude is cheaper and simpler to turn into gasoline and diesel, so it typically trades at a premium; heavy, sour crude needs more complex, costlier refining, so it typically trades at a discount. Both Brent and WTI fall in the "light, sweet" category, but most of the crudes in the OPEC basket, including many Persian Gulf export blends, are heavier and more sour, which is why the basket usually settles below Brent.
Logistics. WTI is delivered inland, at Cushing; moving it to open water and export markets costs pipeline and shipping fees. Brent is loaded onto tankers in the North Sea and goes straight to the global market. This gap in access to open water, separate from quality, is what creates the price spread between Brent and WTI, a spread that widens and narrows from day to day.
A worked example
Suppose that on a given day, a barrel of light, sweet crude similar to Brent trades at 90 dollars on the global market. WTI, with similar or slightly better quality but produced inland in the United States, typically settles a few dollars lower, say 85 dollars, because of the cost of moving it to export markets. The OPEC basket, a weighted average of several heavier, more sour export crudes, typically trades even lower than Brent, say 87 dollars. A similar pattern shows up today: per Sahmino's own feed (aligned with TGJU) and Oilprice.com, Brent is trading around 89 dollars, and per Oilprice.com and Trading Economics, WTI is around 83 dollars, the same few dollar gap that quality and logistics explain.
The transmission channel to Iran
Iran is itself a crude oil exporter, not merely an observer of the world price, which makes this channel more direct than in many other markets. Oil export revenue is a major source of the foreign currency that the central bank and the government count on for imports, the budget, and injections into the currency market; when Brent or the OPEC basket rises, the dollar value of the same export volume rises too, even if the volume sold stays flat. Sanctions have complicated this channel, though: Iranian crude typically sells at a discount to Brent, moved through intermediaries to destinations such as China, and that route sometimes hits bottlenecks and stranded cargoes. The government's annual budget is also built on an assumed price per barrel; if the real market price lands above that assumption, the state books extra revenue, and if it falls below it, the budget deficit widens, a deficit that, per Sahmino's earlier lesson on the state budget, can spill into inflation and the money supply through central bank borrowing. Track both benchmarks live on Sahmino's own Brent price page.
Common mistakes
A common misconception is that "the oil price" is a single global number, when in fact several benchmarks trade simultaneously at any moment, each with its own spread, and news reports typically quote only one of them, usually Brent. A second mistake is treating the spread between Brent and WTI, or Brent and the OPEC basket, as a sign of market trouble; that gap exists in normal times too and comes from quality and logistics differences, not necessarily from a specific event. A third mistake is equating the OPEC basket with Brent; the basket averages several heavier crudes and is not the same number.
Takeaway
Brent, WTI, and the OPEC basket all measure "the oil price," but each is a different average or sample of the world's crude, and quality (API gravity and sulfur) plus delivery logistics create the spread between them. The one thing to remember from this lesson: when you hear a headline about an "oil jump," ask which benchmark it means, because that question is exactly what clarifies the path to export revenue, the budget, and ultimately Iran's currency market. For the broader global channel, see Sahmino's earlier lesson on the world gold ounce and Iran's gold price, or browse the full Sahmino Academy curriculum on the Learn page.
