Add or subtract from a date, one step at a time
Choose a start date, switch between add and subtract, and fill in any mix of years, months, weeks and days. You can leave unused boxes empty. The result is a full date with the weekday written out, so you can tell at a glance whether a deadline lands on a Sunday.
Months are where date sums go wrong. This tool keeps the day number and moves the month. If the target month is shorter, the result is clamped to its last day. So 31 January plus one month is 28 February, or 29 February when that year is a leap year. It is not 3 March.
Years, months and weeks are applied first and days last. Adding 1 year and 2 weeks to a date therefore moves the year, then counts fourteen days forward. A start of 29 February plus one year lands on 28 February of the next year, by the same clamping rule.
Use it for planning a delivery window, a course end date, a reminder cycle or a project milestone. If you want the opposite question, how many days lie between two known dates, the days between dates tool is the better fit.
Worked examples
Questions about this tool
Why is 31 January plus one month not 3 March?
February has no 31st, so the tool stops at the last day of that month. That keeps "one month later" in the next calendar month.
Can I add and subtract in the same calculation?
One direction is used per calculation. Run it twice if you need to go forward and then back.
Does it count weekends?
Yes, every calendar day counts. It does not skip weekends or holidays.