Date Calculator
Calculate days between two dates, add or subtract days from a date, and count business days (excluding weekends). Three modes in one tool.
Your result will appear here.
Date Calculator online
Three modes in one tool: Date Difference (days/weeks/months/years between two dates), Add/Subtract Days (what date is N days from a start date), and Business Days (count weekdays excluding weekends between two dates). All calculations use exact calendar arithmetic.
How it works
Date Difference: Computes the exact calendar difference in days, then converts to weeks (÷7), months (average 30.4375 days), and years (average 365.2425 days). Add/Subtract: Uses native Date arithmetic (milliseconds) to add or subtract the exact number of days. Business Days: Iterates day by day between start and end, counting only Monday–Friday. Leap years and month lengths are handled by the browser's Date object (UTC-based to avoid time-zone edge cases).
Worked example
Difference: 2026-01-01 to 2026-10-08 = 280 days (40 weeks, 9.2 months, 0.77 years). Add 45 business days to 2026-10-08 → lands on 2026-12-10 (45 weekdays = 63 calendar days). Subtract 100 days from 2026-10-08 → 2026-06-30.
Practical tips
- Use business days mode for project planning, contract deadlines and notice periods.
- All calculations use UTC midnight to avoid time-zone shifts that can push the result off by one day.
- Leap years (2024, 2028, 2032…) are handled automatically by the browser's
Dateobject. - For legal/contractual deadlines, always confirm with the applicable jurisdiction's rules (some count the start day, some don't).
Privacy and browser processing
Whenever practical, DailyWebKit processes input locally in your browser. Tools that need network data can depend on external services, browser permissions and CORS. Do not enter confidential information into a third-party network service.
Frequently asked questions
Why does the day count sometimes differ by 1 from other calculators?
Some calculators count the start day, some don't. This tool uses exclusive difference (end - start). If you need inclusive counting, add 1 to the result.
How are business days calculated?
Each day between start (exclusive) and end (inclusive) is checked; Monday–Friday count, Saturday–Sunday skip. Holidays are not excluded in the basic version.
Can I calculate working days for a specific country's holidays?
The basic version only excludes weekends. For country-specific holidays you would need a holiday calendar dataset — not included in this lightweight tool.
Does the tool handle dates before 1970?
Yes. The browser's Date supports a wide range (approx. ±100 million days from 1970). Ancient dates work fine.
Is this tool free?
Yes. It is free and does not require an account.
Does DailyWebKit upload my input?
No. It runs locally in your browser and your input is never uploaded.