A future price at a constant inflation rate is today’s amount times (1 + inflation)^years. Going backward, today’s buying power of a future amount divides by that same factor. The inflation rate is the number you enter. It is not a CPI print from Statistics Canada or the US Bureau of Labor Statistics.
$100 at 3% inflation for 20 years has the same buying power as $180.61 of future dollars. Prices do not have to follow 3%. The figure only shows the constant rate you typed.
It is not a forecast for the United States or Canada. Different items inflate at different rates. The page uses one rate for the whole amount.