Calculators

Calculators currently has one tool, Date Calculator, for two related jobs: finding the exact number of days between two dates, and adding or subtracting days, weeks, months or years from a date. The two aren't quite symmetric — counting days always gives an exact total, but adding calendar months doesn't, since months vary from 28 to 31 days. The calculator handles the edge cases this creates automatically, such as leap years and adding a month to January 31st, which lands on the last real day of February rather than spilling into March.