How do you calculate the number of days between two dates?

Count the whole calendar days from the earlier date to the later date. tilwhen counts the gap exclusively, so it does not count both endpoints. To include the first and last day, add one.

Does the day count include both the start and end date?

No. The result is the gap between the two dates (exclusive). If you want the span that includes both the first and last day, add one to the result.

How many business days are between two dates?

tilwhen shows a business-day figure that skips weekends (Monday–Friday), plus an optional figure that also excludes national public holidays for the country you select.

Days between two dates

Pick a start and end date for the exact gap in total days, weeks, and business days (Monday–Friday), counted in your timezone. It is the gap between the dates, so the start day is day 0 (not counted).

From

days between

From Tuesday, July 21, 2026 to Thursday, August 20, 2026

4 weeks · 22 business days (Mon–Fri)

Also: 2 fortnights, about 2.1 two-week sprints.

Also show the count including the end date (+1)

Public-holiday adjustments

Holiday calendar: None. Choose one to also exclude public holidays.

Holiday calendar

Endpoints counted exclusively (the gap between the two dates).

Calculation receipt

Answer: 30 days
Operation: days_between
Inputs: from: 2026-07-21 · to: 2026-08-20
Timezone: UTC
Convention: Whole calendar days, midnight to midnight; today = day 0 (not counted)
Workweek: mon-fri
Holiday calendar: None
Valid for: 2026-07-21 in UTC
Computed at: 2026-07-21T03:43:57.285Z
Versions: engine 1.0.0 · holiday dataset 2026.07.1
Result ID

Same inputs, engine, and dataset always reproduce this ID; anyone can verify the answer from the fields above.

How the calculation works

tilwhen counts the whole calendar days between the two dates, the gap, not the span. That means the two endpoints are not both counted. If you need the duration that includes both the first and last day (for example, a hotel stay billed "Monday through Friday"), add one to the result. This is the difference between inclusive and exclusive counting, and it is the most common source of off-by-one errors.

What it's useful for

Project and contract durations, how long a period actually runs.
Anniversaries and milestones, days since a wedding, a birth, a job start date.
Trip and event planning, the length of a stay or the gap before an event.
Deadlines, how many days you have left until a fixed due date (see how to count a deadline).

Days, weeks, and business days

Alongside the total days, tilwhen shows the equivalent in weeks and days and the number of business days (Monday–Friday, weekends skipped), plus an optional figure that also excludes national public holidays for your country; see how to count business days correctly for the full method. All counting is done in your local timezone, read why that matters in date math across time zones.

How we calculate

Counts whole calendar days, midnight to midnight, in your local timezone.
Counting is exclusive: today is day 0 and is not counted.
Business days are Monday–Friday by default (other working weeks are selectable where offered). The holiday-aware result skips public holidays only for the holiday calendar you choose in the calculator: United States, United Kingdom (England & Wales, Scotland, or Northern Ireland), Canada, Australia, Uganda, or your own custom list. There is no default calendar; each result names the one used and lists the excluded days.
No login and no server: every result is computed in your browser, so you can verify it yourself.