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Macroeconomics

PCE Inflation Calculator

Enter comparable PCE price indexes to calculate month-over-month and year-over-year inflation.

Inputs

Teaching examples, not official historical observations.

Use one series, reference base and adjustment convention. After calculation, edits update the results immediately. MoM and YoY are distinct.

Results

Start with your numbers

Review or adjust your inputs, then calculate to see your results and interpretation.

Understand this calculation

These are percentage changes in a price index, not changes in spending amounts. A negative rate means the index fell over that interval.

See calculation method and assumptions

Formula

Month-over-month

Year-over-year

Variables, rates and periods

Iₜ
Current-month PCE price index, not spending dollars.
Iₜ₋₁
Previous-month index of the same series (MoM denominator).
Iₜ₋₁₂
Year-earlier index of the same series (YoY denominator).

Separate the reference base from the comparison date

  • An index is neither a dollar amount nor an inflation percentage on its own.
  • If the reference base is 100 and today’s index is 125, prices are 25% above that base, which may be years in the past.
  • Against last month’s 124.5, the increase is about 0.4016%;
  • against the year-earlier 121, it is about 3.3058%.
  • All three statements can be correct because they answer different time questions.
  • Check the comparison before interpreting the percentage: a high price level does not necessarily mean a large increase this month.

Slower inflation does not necessarily mean falling prices

  • If monthly inflation falls from 0.8% to 0.4%, prices are still rising, just more slowly.
  • A negative monthly rate means the index fell from the previous month, but its level may remain above last year or the reference base.
  • Annual inflation also depends on the year-earlier comparison: a higher starting index produces a smaller annual increase for the same current level.
  • That base effect is not evidence of an equally large price decline in the latest month.

Spending dollars and a price index are different

  • Nominal PCE is a spending amount affected by both prices and quantities.
  • The PCE price index measures prices.
  • Dividing two spending totals does not directly produce PCE inflation.

Why does the Federal Reserve monitor PCE?

  • The Fed measures its longer-run 2% inflation goal using the annual change in the PCE price index.
  • Broad coverage and weights that evolve with spending patterns inform its assessment.
  • Policy also considers employment, financial conditions and other evidence rather than a single monthly reading.

PCE versus CPI

  • Both measure consumer prices, but differ in scope, weights and formulas.
  • CPI focuses on households’ direct spending;
  • PCE also includes some consumption paid for by employers or government, such as healthcare.
  • The measures need not agree and their values are not interchangeable.

Headline and core PCE

  • Headline PCE includes food and energy.
  • Core PCE excludes them to help assess underlying price trends.
  • Core is not a complete measure of household living costs;
  • never divide a current core index by a previous headline index.

MoM and YoY answer different questions

  • MoM compares consecutive months;
  • YoY compares the same month a year earlier.
  • YoY reflects twelve months of changes and the comparison base.
  • It can therefore rise even when this month’s MoM rate slows.
  • Match each input to its labeled reference period.

Enter comparable PCE price indexes to calculate month-over-month and year-over-year inflation.

Worked example

  1. Use the same PCE series, reference base and seasonal-adjustment convention.
  2. Compute MoM as (125 / 124.5 − 1) × 100%.
  3. Compute YoY as (125 / 121 − 1) × 100%.

Frequently asked questions

Can an index be zero or negative?

All three indexes must be finite and positive. A zero denominator is undefined, and a negative index is outside this price-index ratio model.

Can I calculate core PCE inflation?

Yes, if all three observations use the same core PCE series. This tool does not convert headline PCE into core PCE.

Are the defaults official data?

No. Defaults only illustrate index ratios. There is no live or official historical data feed.

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