Market Data

The Propane-to-Crude Spread Is the Hidden Edge Under American Plastics

America makes plastic from natural-gas liquids while much of the world makes it from oil, and the spread between propane and crude is where that difference turns into money. It is one of the most consequential ratios in manufacturing that almost nobody outside the trading desks watches.

There is a spread that quietly decides whether American plastics are cheap or expensive relative to the rest of the world, and it is not the price of oil. It is the ratio of propane to crude. US petrochemical plants crack natural-gas liquids like propane into the building blocks of resin, while much of the world cracks oil-derived naphtha, so when propane is cheap relative to crude, American resin makers enjoy a feedstock advantage that shows up all the way down the chain. Propane sits at $0.66/gal (Aug 3, 2026), with no prior-year reading archived yet, and WTI crude at $81.96/bbl, and the relationship between them is worth more to a US molder than the headline oil price ever is.

Two ways to make a polymer

The world's petrochemical industry splits on feedstock. Gas-advantaged regions, the US Gulf Coast above all, crack ethane and propane recovered from natural gas. Oil-based regions crack naphtha, a crude derivative. The two routes make similar products but from different raw materials, so their relative cost swings with the relative price of gas liquids versus oil. When propane runs cheap against crude, the gas-based route wins and US producers undercut naphtha crackers abroad; when the ratio flips, the advantage narrows or vanishes. That is why the propane-crude relationship, not the absolute price of either, is the number that sets competitive position.

Why it reaches a molder who never buys propane

A plastics processor buys resin, not propane, and may never think about natural-gas liquids at all, but the feedstock advantage flows straight into the resin price they pay, at 310.75 index (1982=100) (up about 17.2% from a year ago). When the US feedstock edge is wide, domestic resin is structurally cheaper than it would be on an oil-based cost curve, which supports domestic molding and export competitiveness. When the edge narrows, that support erodes even if the absolute resin price looks stable. So a molder watching only the resin invoice misses the upstream force that explains why their resin is priced where it is relative to a competitor in a naphtha-based region.

America does not make cheap plastic because it is clever. It makes cheap plastic because its feedstock comes out of a gas well, and the propane-crude spread is the scoreboard.

Reading the spread, with its limits

The honest caveats are real: propane is also a heating and export fuel, so its price carries seasonal and international demand that has nothing to do with petrochemicals, and crackers can shift feedstock slates over time, blurring the signal. So the propane-crude spread is a structural-advantage gauge, not a precise resin forecast. But its direction tells a US manufacturer whether the domestic plastics cost base is being helped or hurt by the feedstock economy, which is a strategic input for sourcing, reshoring, and long-term supply decisions that the resin price alone cannot provide. With the spread where it is now, the feedstock story is sliding on the propane side, and worth watching against crude.

The feedstock's full record

Over the five-year record propane has moved decisively rather than oscillated: from $1.12 at the close of 2021 to $0.66 today, down 42%, and now in the lower third of its five-year range. A change of that size across a span this long is a level shift, not a cycle, and planning that assumes a return to the 2021 figure is planning against the whole record.

Use the chemical cost per pound calculator to connect the feedstock picture to your part's material cost. Cost your resin

Published 2026-08-06.