A date calculator adds or subtracts a specified number of days from any start date, giving you the resulting date and day of the week.
About this calculator
A date calculator adds or subtracts a specified number of days from any start date, giving you the resulting date and day of the week. This is useful for deadlines, payment due dates, project timelines, and date-based scheduling.
Date arithmetic is trickier than it looks because months have different lengths and leap years add a day to February. It handles those details for you.
Common uses
- Calculate a deadline that is 30 business days from today
- Find what date falls exactly 90 days from a starting date
- Determine the day of the week for any future date
- Calculate payment due dates from invoice or contract dates
Frequently asked questions
How do I calculate the number of days between two dates?
For date calculations, enter the start date and use the date calculator to add days to reach a target date. For counting days between two known dates, subtract the earlier date's day count from the later date's. Most date calculations involve Julian day numbers for accurate arithmetic across month boundaries.