How is this different from a regular calendar?

The Date Add Subtract Calculator is purpose-built for fast date arithmetic. Unlike manually flipping through a calendar, it supports: 1) Precise offset calculations (e.g., July 22, 2026 + 180 days = January 18, 2027); 2) Business day mode (automatically skips Saturdays and Sundays — ideal for project deadlines and contract dates); 3) Mixed unit offsets (combine days, weeks, months, and years in one calculation); 4) Batch results showing multiple common offsets at once. All calculations happen locally in your browser.

How does business day mode work? Does it skip holidays?

Business day mode automatically skips Saturdays and Sundays. For example: starting from Friday and adding 1 business day will skip the weekend and land on Monday. Note: Business day mode does NOT skip public holidays (which vary by country/region). If you need to exclude holidays, we recommend manually adjusting the result or leaving a buffer.

Can I use multiple units at once?

Yes. You can fill in values for days, weeks, months, and years simultaneously (positive = forward, negative = backward). The tool merges them and computes in order: years → months → weeks → days for accurate results.

Does it handle leap years and month-end correctly?

Absolutely. The tool uses JavaScript's native Date object, which automatically handles leap years, varying month lengths, and year boundaries. For example, January 31 + 1 month correctly resolves to February 28 (or 29 in a leap year), and December 31 + 1 day correctly crosses into the new year.

Is it mobile-friendly? Is my data safe?

Yes, fully responsive — works on phones, tablets, and desktops. All calculations run locally in your browser; no date data is ever sent to any server. You can even use it offline after the initial page load.

📅 Date Add Subtract Calculator

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Free online Date Add Subtract Calculator. Quickly calculate result dates by adding or subtracting days, weeks, months, or years from any base date. Supports business day mode (skip weekends) and calendar day mode. All client-side, no data uploaded.

Zero Dependencies · Works Offline

Updated: 2026-07-22

How to Use

Select the base date (defaults to today)
Enter offset values in Days / Weeks / Months / Years. Positive = forward, negative = backward
Choose Calendar Day or Business Day mode (skip Sat & Sun)
Click Calculate or see real-time results
Batch results for common offsets are shown at the bottom

FAQ

Q: Is business day mode accurate?

Yes. It automatically skips Saturdays and Sundays. Example: Friday + 1 business day = Monday. Note: public holidays are NOT skipped (varies by country).

Q: What do negative values mean?

Negative values calculate backward. e.g., days=-30 means 30 days ago, weeks=-2 means 2 weeks ago.

Q: How are multiple units calculated?

The tool processes in order: years → months → weeks → days, ensuring accurate combined results.

Q: Leap years and month boundaries?

Fully handled by JavaScript's Date object. Jan 31 + 1 month = Feb 28/29. Dec 31 + 1 day = Jan 1 next year.

Q: Is my data safe?

100% local. No date data leaves your browser. Works offline after initial load.

Q: Can I paste text dates?

Use the date picker for best accuracy. For batch processing, pair this with our CSV tools.

📅 Date Add Subtract

How to Use

FAQ

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