Calendar arithmetic
The tools provide date calculations using the conventions described beside each result. They do not determine a person's eligibility for a service or interpret a deadline rule. If a form or process specifies a different counting method, use that stated method.
Date range and precision
Dates are interpreted using the Gregorian calendar from 1600 through 9999. Historical dates recorded in another calendar require conversion first. The tools do not calculate elapsed hours, working days, holiday exclusions or times of day.
Corrections
If an example gives an unexpected result, check the input dates and the selected counting convention. You can report a reproducible issue through the contact page. The guides and tools may be updated as we improve them.