The daily rack price for diesel is not a market quote. A supplier chooses it, starting from the futures market and adjusting for its own costs and position. If you buy at or near rack, knowing the steps tells you whether a price move came from the market or from your supplier.
What is the rack price for diesel?
It is the per-gallon price a supplier posts for diesel loaded at one terminal’s rack. The rack price is quoted per product and per terminal, so a supplier can post different numbers at two terminals on the same day. The glossary entry covers the definition and how rack compares with index and contract pricing.
How are rack prices set?
In four steps: a futures price, a spot price, the supplier’s rack, then your invoice. OPIS, the wholesale price reporting service, gives the first two as a formula: “NYMEX cost basis+/- basis differential = Spot price.” It also says “Spots have direct impact on rack prices” and that refiners “increase or decrease their daily rack costs based on the average daily change in their spot replacement cost.” Spot replacement cost is the spot price plus freight and other costs.
| Step | What it is | Who controls it |
|---|---|---|
| 1. Futures settle | The NYMEX price the market agrees on | Nobody; the market |
| 2. Spot differential | The local premium or discount to futures | Regional supply and demand |
| 3. Supplier’s rack | The posted price at one terminal | The supplier |
| 4. Your invoice | Rack plus whatever your agreement adds | You and the supplier |
Only step 3 is the supplier’s daily decision. OPIS says approximately 220 racks link directly to one of the seven U.S. spot markets, so at those terminals the rack price ties directly to that spot market.
When does the rack price change?
Typically once a day. OPIS says rack price changes “typically go into effect at 6 p.m. each day.” In volatile markets a supplier can repost more than once a day (rack pricing), so a morning quote can differ from an afternoon one. Suppliers also choose when a price becomes effective: OPIS says prices “are never published until a supplier makes them effective.”
What does one day look like?
The numbers here are illustrative, not a real market. On Monday diesel futures settle at $2.40 a gallon and the local spot differential is plus 18 cents, so spot is $2.58. Add 5 cents of freight and other costs, and the supplier’s replacement cost is $2.63. Say the supplier posts $2.67 that evening, a 4-cent margin.
On Tuesday futures settle 5 cents higher, but the spot differential eases 2 cents.
| Monday | Tuesday | Change | |
|---|---|---|---|
| Futures settle | $2.40 | $2.45 | +$0.05 |
| Spot differential | +$0.18 | +$0.16 | -$0.02 |
| Spot | $2.58 | $2.61 | +$0.03 |
| Replacement cost (spot + $0.05) | $2.63 | $2.66 | +$0.03 |
| Supplier’s posted rack | $2.67 | $2.73 | +$0.06 |
The posted rack rose 6 cents. The market explains 3 cents: spot moved from $2.58 to $2.61. The other 3 cents is the supplier widening its margin from 4 cents to 7. If your agreement is rack plus a fixed adder, your invoice moved 6 cents, but only half of it was the market.
How do I tell a market move from a supplier move?
Compare your price change with the spot change over the same period. If they match, the market moved. If your price rose more than spot did, the supplier moved its margin, its position, or costs such as freight. If it rose less, the supplier absorbed some of the move.
Two cautions. Futures alone are an incomplete test, because the differential can offset them, as in the table above. And a supplier’s inventory position is invisible to you, so a gap is a reason to ask, not proof of a fault.
When should I load?
Compare the spot change, not only futures, with your posted price. If spot has risen and your supplier has not yet reposted, the next posting is likely to be higher, so loading at the current rack may be the cheaper choice. If spot has fallen and your rack has not, waiting for the repost, or asking for it, is usually the better choice if your tanks allow it. These are rules of thumb, not guarantees; a supplier may hold a price for its own reasons.
Crude oil is the largest input. The EIA found it accounted for about 51% of the monthly average U.S. retail on-highway diesel price from 2004 through 2025, so a large crude move is likely to reach your rack price, in time.
If you can lift at more than one terminal, compare the rack-plus quotes after freight, as how to compare bulk fuel quotes explains. If you buy across regions, diesel price by region shows how far apart the averages sit. At a carded terminal, you also need the supplier’s card and allocation before the price matters.
What to do when your rack moves
When your supplier’s posted rack changes, set it beside the futures move and the spot change for the same day, and ask about any gap you cannot explain. More for fuel buyers: Energy Connect for buyers.