Loading page
About this tool
Add or subtract days, weeks, months or years from any date and get the exact resulting date.
Date Add Subtract Calculator moves any date forwards or backwards by a mix of years, months, weeks and days and shows the exact resulting date with its weekday, ISO week number and day of year. Month arithmetic is end-of-month safe, so 31 January plus one month correctly lands on the last day of February rather than spilling into March. A business-day mode steps over Saturdays and Sundays for deadline and turnaround calculations.
Open Date Add Subtract Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Adding months to the 29th, 30th or 31st clamps to the last valid day of the target month instead of rolling over, and the tool tells you when it happened.
Years, months, weeks and days can be combined in a single calculation, applied in a consistent, documented order.
Switch on business days and the calculator steps forward or backward over weekends, which is how most SLA and turnaround clauses count.
28 February, or 29 February in a leap year. Since 31 February does not exist, the calculator clamps to the last day of the target month, which is how date libraries and most contracts treat it.
Years and months first, with end-of-month clamping, then weeks and days as plain calendar days. The order matters near month ends, so it is kept fixed and shown on the page.
It ignores the years, months and weeks fields and moves the date one working day at a time, skipping Saturday and Sunday. It does not know about public holidays — add those manually or use a working-days calculator.
Not always. ISO weeks start on Monday and week 1 is the week containing the first Thursday of the year, so early January dates can fall in week 52 or 53 of the previous year.
Add the Date Add Subtract Calculatorwidget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
<iframe src="https://www.altftool.com/embed/widget/date-add-subtract-calculator"
title="Date Add Subtract Calculator — free AltFTool widget"
width="100%" height="640" style="border:0;border-radius:12px;overflow:hidden"
loading="lazy" referrerpolicy="no-referrer-when-downgrade"></iframe>
<p style="font-size:12px;margin:4px 0 0">Widget by <a href="https://www.altftool.com/tools/all/date-add-subtract-calculator?utm_source=embed&utm_medium=widget">AltFTool — free online tools</a></p>