1. What the diesel crack spread is, in one paragraph
The diesel crack spread is the difference between the price of diesel fuel and the price of the crude oil it is refined from, expressed in dollars per barrel; it is the refiner's gross margin on that one product. Refiners do not sell crude, they sell fuel, so profit depends on the gap between what they pay for crude and what they can sell diesel for. When that gap widens, refiners have more incentive to run flat out on diesel-heavy processing, and diesel buyers, from truckers to households burning heating oil, feel the tightness in higher pump and tank prices.
Diesel and heating oil are the same distillate fuel with different dye and tax treatment in most markets, so the two cracks move together. Our heating oil price glossary entry explains how that pass-through works at the retail level.
2. How the diesel crack spread differs from the general crack spread
The general "crack spread" is a family of margin measures across one or more refined products; the diesel crack spread isolates just one of them. Our crack spread glossary page covers the concept in full; this page does not repeat that ground. Diesel sits in the "middle distillate" category with heating oil and jet fuel, so its crack tracks distillate market conditions and seasonal heating demand rather than gasoline demand.
A refiner's overall margin, and the 3-2-1 benchmark described below, blends gasoline and diesel economics. A refinery can have a strong 3-2-1 crack while its diesel crack specifically is exceptional and its gasoline crack only average, or the reverse. Diesel and heating oil buyers should watch the diesel-specific number, not the blended one, and our refining margin glossary entry covers that blended calculation.
3. The 3-2-1 crack spread formula, explained
The 3-2-1 crack spread models a refinery that takes 3 barrels of crude oil and turns them into 2 barrels of gasoline and 1 barrel of diesel or heating oil, then compares the value of that output to the cost of the crude input. The ratio approximates how a real refinery's yield splits between its two largest products, which is why it became the industry's standard shorthand for refining profitability, used by CME Group and traders across the market.
In formula terms: 3-2-1 crack spread = (2 x gasoline futures price in $/bbl + 1 x diesel or heating oil futures price in $/bbl) minus (3 x crude oil futures price in $/bbl), divided by 3 to express it per barrel of crude processed. Each leg is normally priced from a NYMEX futures contract: RBOB gasoline, NY Harbor ultra-low-sulfur diesel or heating oil, and WTI crude.
CME Group also lists "2-1-1" and "5-3-2" variants, using different crude-to-product ratios to give gasoline and diesel a different weight than the 2-to-1 split (CME Group, Crack Conversion Calculator). Which version a desk quotes depends on the refinery slate being modeled; all compare product revenue to crude cost.
| Term | What it represents |
|---|---|
| 3 barrels crude | Input cost side of the formula, usually priced off WTI futures |
| 2 barrels gasoline | Output revenue, priced off RBOB gasoline futures |
| 1 barrel diesel or heating oil | Output revenue, priced off NY Harbor ULSD or heating oil futures |
| Divide by 3 | Converts the total margin to a per-barrel-of-crude figure |
4. A worked example from 11 September 2026: the distillate crack as a diesel-crack proxy
A full 3-2-1 example needs three prices, gasoline, diesel and crude, and this page only has two verified ones for 11 September 2026, so what follows is a distillate crack that stands in for the diesel side without the gasoline leg. NY Harbor heating oil futures traded at $5.10 per gallon that day, per Trading Economics. Multiplying by 42, the gallons in a barrel, gives $214.20 per barrel. WTI crude the same day was $103.80 per barrel, also per Trading Economics. Subtracting crude cost from distillate value gives $214.20 minus $103.80, or $110.40 per barrel.
That $110.40 figure is not the 3-2-1 crack spread: it omits the gasoline leg and treats the whole barrel of crude as if it became distillate. A live RBOB gasoline futures price for 11 September 2026 was not available, so we are not publishing a complete 3-2-1 figure with an invented gasoline price. Treat $110.40 as a directional proxy for that day, and check a live 3-2-1 calculator such as CME Group's for the full three-leg figure.
5. Why the diesel crack has been running wide through 2026
Three forces line up at once: record diesel prices flagged by the International Energy Agency, distillate inventories well below normal, and refineries already running close to full. The IEA's Oil Market Report of 11 September 2026 pointed to record diesel prices. The EIA's most recent reading available as of 11 September 2026 put US distillate stocks 13 percent below the five-year average and refinery utilization at 97.8 percent of capacity, leaving little spare capacity to add diesel output even as the margin to do so widens.
Layered on top is the Strait of Hormuz situation: ship-tracking data from Kpler and Lloyd's List, reported by Al Jazeera on 3 September 2026, put transits at 12 to 13 tankers a day in early September 2026, against a pre-crisis norm near 100. None of this is a forecast of where the crack goes next; it is the set of conditions that has kept it wide this year.
6. What a wide diesel crack means if you buy diesel or heating oil
A wider diesel crack signals that the refining margin on distillate is elevated, which tends to show up as higher pump and tank prices even before crude itself moves. Part of what a household or fleet buyer pays is not crude oil at all, it is the margin refiners can currently charge to turn crude into diesel or heating oil. When the crack widens quickly, retail prices can move even on days crude is flat, because the refining leg is doing the work.
This is why crude benchmarks alone do not fully explain what you pay at the pump or for a delivery. US households heating with oil can see this play out on our New England heating oil winter 2026-27 page, and the lock-in decision is covered on our buy-now-or-wait guide.
See what today's crude, refining and delivery costs add up to for your household.
Run the calculator7. How to read the spread: a quick reference
The table below summarizes how to read the numbers on this page.
| Reading | What it tells you | What it does not tell you |
|---|---|---|
| Distillate crack widening | Refiners earn more per barrel converted to diesel or heating oil right now | The exact 3-2-1 crack, which also needs a gasoline price |
| Distillate crack narrowing | Diesel or heating oil margin pressure is easing relative to crude | Whether crude itself is rising or falling |
| 3-2-1 crack spread (full formula) | Blended refining margin across gasoline and diesel together | The margin on diesel alone, which can differ from the blend |
| Distillate stocks below five-year average | Structural tightness that supports a wide crack persisting | A prediction of the crack's level on a future date |