Category: Troubleshooting & Tips

Reputable tools process dates locally—avoid entering sensitive identifiers alongside personal dates on unknown sites.

Date-only calculators ignore DST; problems appear when adding exact 24-hour intervals across clock-change weekends.

Mobile keyboards and locale settings change picker order—type ISO dates if pickers confuse month and day.

Excel serial dates and 1900 leap bug history cause rare mismatches—align date system and exclusivity rules.

Ambiguous 01/02/2026 reads January 2 or February 1—use ISO yyyy-mm-dd in forms when possible.

Check inclusive settings and whether you counted start day twice—compare against manual count for a three-day sample.