StraightToolsDate Calculator
Add or subtract calendar days from any date.
Calendar days
This calculator includes weekends and holidays. Use the business-days calculator when you want weekdays only.
When to use this tool
Use the date calculator to add or subtract calendar days from a chosen starting date. It is useful for deadlines, travel planning, warranties, schedules, and checking future or past dates.
How the result is calculated
Calendar-day arithmetic advances through every day of the week. Entering a positive number moves forward; entering a negative number moves backward.
Worked example
Starting on August 18 and adding 30 calendar days lands in mid-September. Weekends still count because this tool is based on calendar days rather than workdays.
What to keep in mind
If a deadline uses business days, banking days, court days, or excludes holidays, use the business-day tool and verify the applicable holiday rules.
About our calculations
StraightTools is designed to show the method behind the answer, not just the result. Inputs are handled in your browser for this tool. For important financial, legal, medical, tax, safety, or contractual decisions, verify the result with an appropriate authoritative source or qualified professional.
Popular date lookups
109 days from today278 days from today194 days ago274 days ago294 days ago
Use these quick guides or enter any custom date and day count in the calculator above.
Date calculator guide
Use the date calculator to add or subtract calendar days from a starting date. Calendar-day calculations count every day on the calendar, including Saturdays, Sundays, and holidays.
Calendar days vs. business days
If a deadline is stated in calendar days, weekends are included. If it is stated in business days, weekends are normally excluded and holiday treatment can depend on the organization or jurisdiction. For workday planning, use the Business Days Calculator rather than a calendar-day result.
Common date calculations
Date math is useful for project deadlines, return windows, travel planning, contract periods, appointments, school schedules, countdowns, and historical lookbacks. For the span between two fixed dates, use Days Between Dates.
Date calculator FAQ
Does the calculator count weekends?
Yes for calendar-day calculations. Saturdays and Sundays are normal calendar days.
What does “days from today” mean?
It means moving forward by the stated number of calendar days from the current date. The result changes as the current date changes.
What does “days ago” mean?
It means moving backward by the stated number of calendar days from the current date.
Should I use calendar days for a legal or financial deadline?
Only if the governing rule specifically uses calendar days. Rules can define weekends and holidays differently, so confirm the applicable terms for important deadlines.
Popular date calculations
These date calculations are commonly searched and use the same calendar-day method as the calculator above.
194 days ago109 days from today259 days from today249 days from today187 days from today178 days from today170 days from today450 days from today