A browser-local tool
Percentage change, without mixing up the measures.
Enter two values of the same measure, unit, index base and comparable periods. The calculation happens in your browser; nothing is sent to Younivi. For two percentage rates, choose that option to see the difference in percentage points separately from relative percent change.
How to read the result
For a level moving from 100 to 120, ((120 − 100) ÷ 100) × 100 = +20%. Moving back from 120 to 100 is −16.67%, not −20%, because the starting base has changed. This is a change within one series, not a way to compare absolute prices across countries.
For rates moving from 3.5% to 4.0%, the difference is +0.5 percentage points. The relative change in the rate is ((4.0 − 3.5) ÷ 3.5) × 100 = +14.29%. Neither figure is a 0.5% change in an index level. If the starting rate is zero, the point difference can be stated, but the relative percent change is undefined; this calculator requires a positive starting value.
Nominal and real values answer different questions. Do not compare a nominal wage or GDP level with its inflation-adjusted counterpart as though they were successive observations of the same measure. Likewise, an index with one reference base cannot be compared directly with an index on a different base.
Use it with the right series
- How to read CPI indexes explains why index bases and frequencies matter. Open Price Index for the source-labelled levels.
- GDP per capita versus GDP growth distinguishes a level from a growth rate. Open GDP for country series.
- Mean versus median earnings explains why two wage measures should not be treated as one history. Open Wages for source details.
This is arithmetic for comparable inputs, not a data feed, inflation adjustment, or financial advice. Check each publication’s period, definition and source before using a result.