Summary
Add or subtract a whole number of calendar days from a start date.
Calculation details
Negative days move backward. Leap days are handled as UTC calendar dates.
Formula
Result = start UTC date + days.
Worked example
Worked example
January 15 plus 10 days is January 25.
How it works
Enter a start date and a whole number of days (negative to go backward). Leap days are handled as UTC calendar dates.
Frequently asked questions
Can I add negative days?
Yes. Negative values move the result date backward from the start date.
Are business days enforced?
No. This adds calendar days. Use business-day tools when weekends must be skipped.
Does time of day matter?
No. Dates are handled as UTC calendar dates without clock time.