Polystyrene and EPS: Correlation
Prices it moves with, and why
Polystyrene and expanded polystyrene are polymerised from styrene, which makes up nearly all of their cost. They are used in packaging, appliances and building insulation, and lose ground to polypropylene and PET in many packaging uses.
Proxy US PPI: thermoplastic resins and plastics materials index (BLS base period) · monthly, Jan 2006 to Sep 2026There is no free public price for Polystyrene and EPS itself, so this tab uses the closest public series as a stand-in. Read the numbers as an indication, not as the price of this exact item.
What its price moves with
Selected linkPolystyrene and EPS and Styrene
Monthly changes 0.38 weak correlation 12-month changes 0.73 strong correlation Last 5 years 0.09 monthly changes Lead or lag none No clear lead or lag Price function, Jan 2006 to Sep 2026 Polystyrene and EPS ≈ 6.37 × (Styrene)0.69 R² 0.79 On this fit, a 10% higher styrene price goes with a 6.8% higher Polystyrene and EPS price over the long run. Units: index (BLS base period) and index (BLS base period).Chart: Polystyrene and EPS and Styrene prices rebased to 100 at Jan 2006, log scale
Both prices rebased to 100 at Jan 2006, on a log scale so equal percentage moves look the same size.Chart: Polystyrene and EPS price against Styrene price, monthly, log scales, with fitted line
Each dot is one month; paler dots are older (2006), darker dots recent (2026); the ringed dot is the latest month. The dashed line is the fitted price function. Both axes are logarithmic.Styrene is nearly all of the raw material cost, so polystyrene prices are set as a margin over styrene. The cyclic intermediates proxy moves with the resin proxy at 0.38 monthly and 0.73 yearly.
weak co-movement month to month · 249 months Show chartsBenzene is the main raw material behind styrene and so behind polystyrene. The petrochemical proxy moves with the resin proxy at 0.71 monthly and 0.89 yearly, which mostly reflects the broad resin index.
strong co-movement month to month · 249 months Show chartsHigh-impact polystyrene contains polybutadiene rubber for toughness, so rubber costs matter for that grade. The synthetic rubber proxy moves with the resin proxy at 0.38 monthly and 0.60 yearly. General-purpose grades contain none.
weak co-movement month to month · 249 months Show chartsPolypropylene and PET replace polystyrene in many cups, trays and food containers, especially where rules restrict expanded polystyrene. They share the same proxy index here, so no separate statistics are shown.
Not enough overlapping price history to measure.Oil sets the cost of benzene and ethylene behind styrene. Brent moves with the resin proxy at 0.24 monthly and 0.72 yearly. The monthly tie is loose because polystyrene margins swing with styrene supply and packaging demand rather than with oil directly.
weak co-movement month to month · 249 months Show chartsHow to read these numbers
Correlation of monthly changes (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak.
12-month changes compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs.
Price function is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation.
Lead or lag checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months.
Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link.
Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site.