Add or subtract a chosen number of calendar days from a date. Month lengths and leap years are handled automatically.
Result date = start date ± whole number of calendar days.
February 28, 2024 plus 1 day is February 29, 2024. In 2025 the same operation gives March 1. Adding 7 days keeps the same weekday.
This is calendar-day arithmetic, not business-day arithmetic. It does not postpone a deadline that falls on a weekend or public holiday. Legal and contractual deadlines can use different counting conventions.
Editorial responsibility: Nicolas Belotti · Methods and testing · Report an error
English edition: 16 September 2026.