US consumer prices rose 3.7% in the 12 months to September 2026, up from 3.4% in the year to August. The charts above split that rise into the categories that caused it. This note explains what they show and how to read them.
Where the 3.7% comes from
Split into the four groups that make up the whole basket, core services accounted for 50.9% of the rise, energy for 36.2%, food for 9.0% and core goods for 3.8%.
Two categories do most of the work, and they are now level. Shelter, the rent households pay and the rental value of the homes they own, accounted for 30.6% of all inflation on its own. Motor fuel accounted for 30.7%, with gasoline prices 34.2% higher than a year earlier. Together, shelter and motor fuel explain 61.2% of the rise. In August the split was 31.7% shelter and 26.8% fuel; September's 9.1% jump in gasoline prices closed that gap.
Food added 9.0%, split between meals away from home (5.0%) and groceries (4.0%). Core goods barely moved: used car and truck prices fell 1.5%, which on its own took 0.9% off the rise.
A big price rise is not a big contribution
Ranking categories by how fast their prices rose gives a misleading picture of what drives inflation. Fuel oil prices rose 74% over the year, faster than anything else in the index, but fuel oil is about a tenth of a percent of household spending, so it accounted for just 1.6% of inflation. Shelter prices rose only 3.2%, yet shelter is 35.3% of the basket, so it accounted for 30.6%.
How much a category adds depends on both its price change and its weight in the basket. That is why the charts rank categories by their share of the rise and show the price change beside it, never the other way round.
| Category | Price change, 12 months | Share of the basket | Share of the rise |
|---|---|---|---|
| Fuel oil | +74.2% | 0.12% | 1.6% |
| Gasoline | +34.2% | 3.85% | 29.2% |
| Airline fares | +22.4% | 1.04% | 5.4% |
| Owners' equivalent rent | +3.3% | 25.90% | 22.8% |
| Eggs | -20.6% | 0.12% | -0.8% |
| Motor vehicle insurance | -5.0% | 2.53% | -3.6% |
Falling prices work the same way. Egg prices dropped 20.6%, but eggs are such a small part of spending that they took only 0.8% off the rise. Car insurance fell just 5.0% and pulled inflation down more than four times as much.
Month by month: fuel came, went and came back; shelter stayed
The 12-month figure hides how unevenly prices moved. Over the six months from April to September 2026, core services accounted for 58.0% of the combined rise and energy for 29.8%.
Energy's share swung both ways. April and May added 30.7% of the six-month rise, June and July took back 29.9% as fuel prices fell, and August and September added 28.9% as they climbed again; in September alone gasoline accounted for over half of the month's all-items increase. Motor fuel's net share over the six months was 25.9%. Shelter pushed prices up in every one of the six months and accounted for 35.5% of the rise, less dramatic but far steadier.
That difference matters for where inflation goes next. A fuel-driven rise can reverse within months, as June and July showed, and return just as fast. A shelter-driven rise tends to persist, because rents reset slowly.
How to read the shares
Each bar shows a category's share of the change in the level above it, so the bars at every level add up to 100%. Open Energy and its parts split Energy's rise; open Food and they split Food's.
Sometimes the parts pull in opposite directions. Then each bar shows its share of all the movement, up or down, and an arrow marks which way it pushed prices. Inside meats, poultry, fish, and eggs, for example, meat, poultry and fish made up 56.3% of the movement, pushing prices up, while eggs made up 43.7%, pulling them down.
The month card adds up 1-month contributions, seasonally adjusted, so each price move is counted once and the months sum to the change over the whole period. Adding 12-month figures from consecutive months would count the same price moves many times over, so the page never stacks them.