YOUR NUMBERS · YOUR DEVICE
Practical guides
Calculate percentage changes, compound growth and total costs using your own numbers. Preview and download the results in your browser.
Percentage change: choose the correct starting value
A percentage change compares a difference with the value you started from. The denominator matters as much as the difference.
Percentage points and percent are different
A rate changing from 10% to 12% can be described in two valid but distinct ways.
Compound growth: a repeated-rate model
Compounding means applying each new change to the value after the previous change.
Match the rate to the period
The number of periods and the rate must describe the same time interval.
Compare total costs, not just price labels
A lower unit price does not always mean a lower total cost.
Read and keep your CSV results
CSV files are simple text tables that can be opened in common spreadsheet applications.