Daily Life

Days Between Two Dates Calculator

Q: Does the calculator include the start date in the count?

**No**. It counts complete days **between** the two dates (the start date is not counted, the end date is). If both dates are the same, the result is **0**. If you need an inclusive count (e.g., vacation days), add 1 to the result.

Q: Do business days include public holidays?

**Not currently**. The calculator only excludes Saturdays and Sundays. If you need a precise count for legal or financial deadlines, manually subtract any public holidays that fall within the period.

Q: How does it handle leap years?

**Automatically**. The millisecond difference between two dates respects the actual Gregorian calendar. If your period includes a February 29 (years 2024, 2028, 2032...), that day is counted.

Q: What happens if the 'from' date is after the 'to' date?

The calculator returns the **absolute value** of the difference. Whether you enter dates in chronological order or reverse, you get the same positive number of days.

Q: How many business days are in a typical month?

On average **21 to 23 business days** per month (depending on how weekends fall). A month with 5 Saturdays and 5 Sundays has 21 business days; one with only 4 of each has 23. Subtracting public holidays (1-3 per month on average) brings the actual business days to 19-22.

Q: How do I calculate legal deadlines in business days?

Legal deadlines typically exclude weekends and **public holidays**. Some jurisdictions also exclude court vacation periods. For important legal deadlines, verify with the specific court or administrative body, as rules vary by jurisdiction.

Q: Does the calculator account for time zones?

It uses your **browser's local time zone**. For normal use (same time zone for both dates), this doesn't affect the result. If you need precise cross-timezone calculations (e.g., flight departures), account for time zone differences manually.

Q: What are common uses for weeks between dates?

In **pregnancy tracking** (40 weeks of gestation), **training programs** (4-12 week blocks), **project sprints** (typically 2-week sprints), **biweekly payments**, and **recurring task scheduling**. Weeks = days / 7.

Calculate the exact number of days, business days, weeks, months, and years between any two dates. Handles leap years automatically. Free, instant.

Data verified · June 2026
Edited by Martín Rodríguez
Formula verified by automated tests
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Calculator Free · Private

Edited by: Martín Rodríguez (editorial policy )

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How to use this calculator

Follow this tool’s steps, then review its formula, assumptions, and limits below.

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Calculating the exact number of days between two dates in MM/DD/YYYY format is a daily need: counting PTO eligibility, hitting an IRS filing deadline, tracking job tenure for benefits vesting, calculating contract terms, or knowing how many days until your due date. This calculator takes a start date and end date and returns total calendar days, US business days (Monday–Friday), weeks, months, and years. It handles leap years automatically and works for past or future dates — useful when the IRS, SSA, or your HR department asks for a precise day count. Note: this tool excludes only weekends, not the 11 US federal holidays observed by the Office of Personnel Management (OPM); subtract those manually if needed.

When to use this calculator

You signed a contract and want to know how many days until the expiration date.
You're planning a trip and need to know how many days you'll be away.
You need to calculate job tenure or length of service.
You want to know how long ago an important event occurred.
You're a lawyer or accountant counting deadlines in business days.

11 US Federal Holidays 2026 — subtract from business day counts (OPM)

Holiday	2026 Date	Day of week
New Year's Day	January 1	Thursday
Martin Luther King Jr. Day	January 19	Monday
Presidents' Day (Washington's Birthday)	February 16	Monday
Memorial Day	May 25	Monday
Juneteenth National Independence Day	June 19	Friday
Independence Day	July 4	Saturday (observed Jul 3, Fri)
Labor Day	September 7	Monday
Columbus Day	October 12	Monday
Veterans Day	November 11	Wednesday
Thanksgiving Day	November 26	Thursday
Christmas Day	December 25	Friday

Source: US Office of Personnel Management (OPM) — Federal Holidays 2026 (opm.gov). These 11 holidays are excluded from federal business-day counts. Private employers may follow a different holiday schedule.

How it works

How Days Between Dates Are Calculated

The simplest and most accurate method:

days = (end_date - start_date) / 86,400,000 ms

The difference in milliseconds between the two dates (JavaScript uses Unix timestamps) is divided by the number of milliseconds in one day (86,400,000 = 1000 ms x 60 s x 60 min x 24 h).

Types of Day Counts

Calendar Days

Counts all days, including weekends and holidays. This is the most common count and the default.

Business Days

Counts only Monday through Friday, excluding Saturdays and Sundays (and optionally public holidays). Used for administrative deadlines, banking operations, legal filings, and commercial terms.

Calendar Days in Common Periods

Period	Calendar Days
1 week	7
2 weeks (fortnight)	14
1 month	28 to 31
1 quarter	90 to 92
1 semester	181 to 184
1 year	365 or 366

When Are Business Days Used?

Business days are standard for:

Legal deadlines (court filings, statute of limitations)

Administrative filings (tax returns, government applications)

Banking operations (check clearing, wire transfers)

Contract terms when specified as 'business days'

Project management (sprint planning, delivery timelines)

Leap Year Rules

A year is a leap year if:
1. It's divisible by 4, AND
2. It's NOT divisible by 100, UNLESS
3. It's also divisible by 400.

Examples: 2024 is a leap year (divisible by 4, not by 100). 1900 was NOT (divisible by 100, not by 400). 2000 WAS (divisible by 400).

This calculator handles all of these automatically.

Common Applications

Contract Deadlines

If a contract says '10 business days from April 1', the deadline is approximately April 15 (accounting for 2 weekends). Always check whether the contract specifies calendar or business days.

Job Tenure

The difference between your start date and today gives total days of employment. Convert to years and months for seniority calculations.

Pregnancy

40 weeks (280 days) from the first day of the last menstrual period gives the estimated due date.

Trip Planning

Calculate total nights for hotel bookings, meal counts, and packing.

Age Calculation

Total days from birth date to today, converted to years, months, and days.

Common Mistakes

1. Counting from day 0 vs day 1: if someone says '10 days from the 1st', is that the 10th or the 11th? Convention: counting starts from the next day, so the answer is the 11th.
2. Confusing calendar days with business days: legal and financial deadlines almost always specify which type.
3. Not excluding holidays in business day counts: this calculator only excludes weekends (Saturdays and Sundays). Manually subtract public holidays if your calculation requires them.
4. Ignoring leap years: if the period includes February 29, add 1 day to your manual count. This calculator handles it automatically.
5. Time zone issues: if dates are created in UTC and you're in a different time zone, there can be a 1-day difference at midnight boundaries.

Example: From 01/01/2026 to 04/14/2026

From date: 01/01/2026.

To date: 04/14/2026.

Calendar days: January (31) + February (28) + March (31) + 14 days of April = 103 days.

Weeks: 103 / 7 = 14.7 weeks.

Months: 3 months and 13 days.

US business days (excluding Saturdays/Sundays only): approximately 74 business days (subtract any of the 11 federal holidays in the range — e.g., MLK Day, Presidents' Day — if your deadline excludes them).

Between 01/01/2026 and 04/14/2026 there are 103 calendar days or about 74 US business days (before subtracting federal holidays).

Frequently asked questions

Does the calculator include the start date in the count?

No. It counts complete days between the two dates (the start date is not counted, the end date is). If both dates are the same, the result is 0. If you need an inclusive count (e.g., vacation days), add 1 to the result.

Do business days include public holidays?

Not currently. The calculator only excludes Saturdays and Sundays. If you need a precise count for legal or financial deadlines, manually subtract any public holidays that fall within the period.

How does it handle leap years?

Automatically. The millisecond difference between two dates respects the actual Gregorian calendar. If your period includes a February 29 (years 2024, 2028, 2032...), that day is counted.

What happens if the 'from' date is after the 'to' date?

The calculator returns the absolute value of the difference. Whether you enter dates in chronological order or reverse, you get the same positive number of days.

How many business days are in a typical month?

On average 21 to 23 business days per month (depending on how weekends fall). A month with 5 Saturdays and 5 Sundays has 21 business days; one with only 4 of each has 23. Subtracting public holidays (1-3 per month on average) brings the actual business days to 19-22.

How do I calculate legal deadlines in business days?

Legal deadlines typically exclude weekends and public holidays. Some jurisdictions also exclude court vacation periods. For important legal deadlines, verify with the specific court or administrative body, as rules vary by jurisdiction.

Does the calculator account for time zones?

It uses your browser's local time zone. For normal use (same time zone for both dates), this doesn't affect the result. If you need precise cross-timezone calculations (e.g., flight departures), account for time zone differences manually.

What are common uses for weeks between dates?

In pregnancy tracking (40 weeks of gestation), training programs (4-12 week blocks), project sprints (typically 2-week sprints), biweekly payments, and recurring task scheduling. Weeks = days / 7.

Sources & references

Methodology & trust

Editorial

Daily Life calculator with its formula verified automatically against US Office of Personnel Management (OPM) — Federal Holidays, per our editorial policy and methodology.

Updates

Updated: June 2026. Parameters are verified periodically against the cited sources.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). Days Between Two Dates Calculator. Hacé Cuentas. https://hacecuentas.com/en/date-difference-calculator

Content licensed under CC-BY 4.0 — reuse it citing the source with a link to Hacé Cuentas.

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