Date Calculator

Calculate differences between dates, add or subtract days, months, and years. Perfect for planning and scheduling.

Start Date

End Date

Include end date in the count

Quick Calculations

How to Use the Date Calculator

Choose Mode

Select Date Difference or Add/Subtract mode

Enter Dates

Input your start date, end date, or base date

Calculate

Click to calculate difference or result date

View Results

See detailed breakdown in multiple time units

Understanding Date Calculations

What is Date Calculation?

Date calculation helps you determine the time span between two dates or find a future/past date by adding or subtracting time intervals. Essential for planning, scheduling, and tracking time-sensitive events.

• Date Difference: Calculate years, months, days between dates
• Add Time: Project dates into the future
• Subtract Time: Calculate past dates accurately
• Multiple Units: Work with years, months, weeks, and days

Why Use a Date Calculator?

Manual date calculations can be error-prone due to varying month lengths and leap years. Our calculator handles all complexities for accurate results every time.

• Project Planning: Calculate deadlines and milestones
• Event Coordination: Plan events and countdowns
• Age Calculations: Determine exact ages or tenures
• Quick Shortcuts: Preset buttons for common calculations

Common Date Intervals

Interval	Days	Typical Use
1 week	7	Weekly reviews, sprints
1 fortnight	14	Payroll cycles (bi-weekly)
1 month (avg)	30.44	Billing, subscriptions
1 quarter	~91.3	Business reporting
1 year	365	Anniversaries, contracts
1 leap year	366	Feb 29 accuracy
90 days	90	Trial periods, visas, probation
180 days	180	Schengen stay limit, warranties

Worked Examples

Days between 2026-01-01 and 2026-08-16

31 + 28 + 31 + 30 + 31 + 30 + 31 + 15 = 227 days (2026 is not a leap year)

90 days from 2026-08-16 (a trial period)

2026-08-16 + 90 days = 2026-11-14

Weeks between two dates

days ÷ 7; e.g. 227 days = 32 weeks and 3 days

Business days ≠ calendar days

The Date Difference result now shows business days (Monday–Friday) and weekend days alongside calendar days. Public holidays are not deducted, since they vary by country — subtract them manually if your deadline rule requires it.

Inclusive vs Exclusive Counting

One of the most common off-by-one sources: does "days between Jan 1 and Jan 3" mean 2 days (exclusive — the difference) or 3 days (inclusive — counting both endpoints)? Contracts and visa rules often count inclusively; age and duration calculations count exclusively. This tool reports the difference (exclusive) unless you tick "Include end date", which switches to inclusive counting for the total, business-day, and weekend-day figures.

Leap Year Rules

A year is a leap year in the Gregorian calendar when it is divisible by 4, except century years (divisible by 100), which must also be divisible by 400. This keeps the average year at 365.2425 days, closely matching the tropical year.

• 2024, 2028, 2032, 2036 — leap years (divisible by 4, not centuries)
• 1900 — not a leap year (divisible by 100, not by 400)
• 2000, 2400 — leap years (centuries divisible by 400)
• 2100 — not a leap year (the next skipped century)

Leap years matter for date math: February grows from 28 to 29 days, so a span crossing February 29 in a leap year is one day longer. People born on February 29 celebrate on February 28 or March 1 in common years, depending on local convention.

Business Days in 2026

Working days per month in 2026, counting Monday–Friday and ignoring public holidays. The whole year has 261 business days and 104 weekend days.

Month	Days	Weekends	Business
January	31	9	22
February	28	8	20
March	31	9	22
April	30	8	22
May	31	10	21
June	30	8	22
July	31	8	23
August	31	10	21
September	30	8	22
October	31	9	22
November	30	9	21
December	31	8	23
Full year 2026	365	104	261

Dual Mode Calculator

Calculate date differences or add/subtract time from any date with equal precision.

100% Private

All calculations are performed locally in your browser. Your dates are never stored or transmitted.

Completely Free

No registration required, no limits. Calculate dates as often as you need, absolutely free.

Date Calculator FAQ

How do I count business days between two dates?

Enter your start and end dates in Date Difference mode and read the Business Days card in the results. Business days count Monday through Friday only; Saturdays and Sundays are shown separately as weekend days. Public holidays are not deducted because they differ by country — if your contract counts working days excluding holidays, subtract the number of holidays that fall on a weekday in your period. For example, Jan 1 to Mar 31, 2026 contains 63 business days before holidays.

Does the date difference include the end date?

By default the difference is exclusive: Jan 1 to Jan 3 equals 2 days. Tick "Include end date in the count" to switch to inclusive counting, which adds one day — the convention used by contracts, visa stays, and notice periods. The total days, business days, and weekend days all follow the same setting.

How are leap years handled?

The calculator uses real calendar arithmetic, so a span that includes February 29 automatically gets the extra day. A year is a leap year when it is divisible by 4, except century years must be divisible by 400 — so 2028 is a leap year but 2100 is not. The years/months/days breakdown also respects variable month lengths of 28 to 31 days.

What happens when adding a month lands on an invalid date?

Adding one month to January 31 cannot produce February 31, so the result rolls over to the last valid day of the target month: February 28 (or 29 in a leap year). This is the same convention used by most calendar software. If you need strict month-end behavior, verify the result date shown and adjust by one day if your use case requires it.

My deadline lands on a weekend — when is it actually due?

That depends on the governing rules, not the math. Common conventions move a weekend deadline to the next business day (banking, many legal codes) or keep it on the calendar date (some employment contracts). Use Date Difference with the weekend-days figure to see how many non-working days your window contains, then apply your specific rule.

How is this different from an age calculator?

A date calculator measures the interval between any two arbitrary dates. An age calculator is a specialization: it always measures from a birth date to today and reports age in completed years, months, and days. If your goal is "how old am I", use the Age Calculator; for deadlines, anniversaries, project spans, and historical intervals, this tool is the right choice.

Date Calculator

Date Difference

Result Date