Refining and reforming: Correlation
Prices it moves with, and why
The index tracks US refinery output prices, which largely follow crude oil plus the refining margin for petrol, diesel and jet fuel. Margins widen when refinery capacity is short and narrow when new plants open, mainly in Asia and the Middle East.
Price index US PPI: petroleum refineries index · monthly, Jan 2006 to Sep 2026What its price moves with
Selected linkRefining and reforming and Crude oil
Monthly changes 0.79 strong correlation 12-month changes 0.96 strong correlation Last 5 years 0.76 monthly changes Lead or lag none No clear lead or lag Price function, Jan 2006 to Sep 2026 Refining and reforming ≈ 7.37 × (Crude oil)0.85 R² 0.87 On this fit, a 10% higher crude oil price goes with a 8.5% higher refining and reforming price over the long run. Units: index and $/bbl.Chart: Refining and reforming and Crude oil 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: Refining and reforming price against Crude oil 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.Crude oil is the main input and most of a refinery's cost, so product prices track it closely. Monthly moves correlate at 0.79 and yearly at 0.96, with the gap reflecting the refining margin, which moves with fuel demand and plant outages.
strong co-movement month to month · 249 months Show chartsDiesel, used in tractors, trucks and pumps, is a main refinery product. The diesel proxy correlates with the refinery index at 0.89 monthly and 0.98 yearly, since diesel is a large part of what the index measures.
strong co-movement month to month · 249 months Show chartsCatalytic reforming in refineries yields aromatics such as benzene alongside petrol components. The petrochemicals proxy correlates at 0.68 monthly and 0.90 yearly, because both are priced off crude oil and compete for the same reformate.
moderate co-movement month to month · 249 months Show chartsRefineries burn gas for heat and reform it into hydrogen for desulphurisation. Monthly moves barely correlate with European gas but yearly moves reach 0.69, showing a slower, partly shared energy cycle rather than tight cost pass-through.
little or none co-movement month to month · 249 months Show chartsRefineries are the largest users of hydrogen, mostly made on site from gas, to remove sulphur from fuels and crack heavy oil. The US hydrogen index barely tracks refinery prices, at -0.15 monthly, because merchant hydrogen is sold on long contracts.
little or none co-movement month to month · 208 months Show chartsCracking and hydrotreating rely on catalysts containing zeolites, molybdenum, nickel, cobalt and platinum. Catalyst costs are small next to crude, but metal price spikes raise them; there is no public price series here.
Not enough overlapping price history to measure.How 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.