Tonga inflation calculator by year

The Yearly Inflation Calculator is a free online tool that shows how inflation changed the value of money between any two years. You choose a country, enter an amount, pick a start year and an end year, and it returns the inflation-adjusted value along with cumulative inflation, the average annual rate and the change in purchasing power. It uses official Consumer Price Index data rather than a guessed rate, and covers 192 countries.

Inflation is calculated from a price index, usually the Consumer Price Index. Take the index value at the end of the period, subtract the index value at the start, divide by the index value at the start, and multiply by 100. If the index moved from 120 to 126, inflation was (126 − 120) ÷ 120 × 100 = 5%. The index itself comes from pricing a fixed basket of goods and services repeatedly over time.

For a single year, the annual inflation rate compares that year’s index with the previous year’s: rate % = (CPI_this_year ÷ CPI_last_year − 1) × 100. Across a longer period, the average annual rate is the geometric mean — the constant rate that compounds to the same total: annual % = ((CPI_end ÷ CPI_start) ^ (1 ÷ number of years) − 1) × 100. It is deliberately not the simple average of the yearly rates, which would overstate the result because inflation compounds.

All figures come from the World Bank’s Consumer Price Index series (indicator FP.CPI.TOTL), which compiles the official CPI published by each country’s national statistics agency — the Bureau of Labor Statistics in the United States, the Office for National Statistics in the United Kingdom, MoSPI in India, and so on. The data is annual. It is built into the site rather than fetched live, so results are fast and stable.

Countries began publishing a consistent Consumer Price Index at different times, and some series have gaps where no figure was published. The year menus only ever offer years that have a published figure for the country you have selected, so you cannot pick a year the data does not support.

National calculators often compare specific months, or use a variant index, while this tool compares annual averages. Statistics agencies also revise and re-base their series periodically. Differences of a fraction of a percent are normal and expected; the magnitude and direction of the result will always agree.