Add or subtract days, weeks, months, or years from any date and instantly get the result date and day of the week.
Pick a start date, an amount and a unit, then click Calculate Date
This free date calculator answers a simple but surprisingly common question: what date is it going to be, or was it, X days, weeks, months, or years from a date I choose? Pick a Start Date, decide whether you're adding or subtracting, enter an amount and a unit, and the calculator instantly returns the exact result date along with its day of the week.
Enter any Start Date, choose Add or Subtract, set an amount, and pick a unit — Days, Weeks, Months, or Years. Click Calculate Date and the tool returns the resulting calendar date, its full day of the week, the total number of days that separate the two dates, the ISO week number of the result, and how many days that result falls from today. Quick preset chips fill in common date-math shortcuts like +30 days or +1 year in a single click.
Anyone who needs to work out a target date quickly: project managers setting a deadline a fixed number of days out, HR teams calculating a probation or notice-period end date, shoppers figuring out a return-by date, renters tracking a lease renewal, or anyone counting down to or back from a birthday, anniversary, or appointment.
The logic behind the result date, week number, and day count
Adding or subtracting months moves the date to the same day-of-month in the target month whenever that day exists, rather than approximating a month as exactly 30 days.
If the target month is shorter than the Start Date's day-of-month (e.g. adding one month to January 31), the date rolls forward into the following month, matching standard calendar-library behavior.
February 29 is handled correctly with no special-case input from you, since the calculation relies on native calendar arithmetic rather than a fixed 365-day year.
From picking a start date to reading the result
Choose the date you want to calculate from — it defaults to today's date.
Select whether you want to move forward (Add) or backward (Subtract) from the Start Date.
Type a number in Amount and choose Days, Weeks, Months, or Years from the Unit dropdown, or click a preset chip.
See the exact result date, its day of the week, total days moved, ISO week number, and how far it falls from today.
Two scenarios: adding days, and adding months across an end-of-month edge case
Suppose Start Date is 2026-07-31 and you add 45 days.
Start Date is 2026-01-31, Add 1 Month.
Common everyday situations where quick date math saves time
Add 30 or 60 days to an issue date to find a Net-30 or Net-60 payment deadline.
Add a store's return-policy window (e.g. 14 or 30 days) to a purchase date to find the return-by date.
Add a billing cycle length to a start date to find the next renewal or free-trial expiry date.
Add or subtract a contractual notice period from a resignation or termination date.
Subtract years from today to double-check an age, or add years forward to plan a milestone celebration.
Subtract 60 or 90 days from a lease end date to set a renewal-decision reminder.
Add typical transit days to an order date to estimate an arrival window.
Add weeks to a term start date to find assignment or exam dates.
Add a set number of days or weeks to a start date to schedule a follow-up.
What this Date Calculator does well, and where it has boundaries
Get the most accurate result from your date calculation
Summary: This Date Calculator adds or subtracts days, weeks, months, or years from any date and returns the exact result date, day of the week, and week number — free, instant, and entirely client-side. If you instead need the gap between two known dates, use the Date Difference Calculator.
Common questions about date addition and subtraction
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