Weeks
0.0
Date Calculator
Calculate days between two dates, or add/subtract days from a date.
Days Between Dates
0 days
Months (approx)
0.0
Business Days (approx)
0
How to use the Date Calculator
The Date Calculator is free and runs entirely in your browser — no sign-up, and nothing you enter leaves your device. It opens pre-filled with a realistic example, so you can see how it works before replacing any figure with your own; the results update as you type. Press Calculate to refresh the result panel, or Reset to return to the example.
The inputs it asks for:
- Start Date — a calendar date.
- End Date — a calendar date.
The formula
It converts both dates to a day count and subtracts them, then expresses the gap in weeks and approximate months and business days:
Days = End date − Start date
Weeks = Days ÷ 7 · Months ≈ Days ÷ 30.44 · Business days ≈ Days × 5/7- Months
- uses 30.44, the average days per month across a year
- Business days
- ≈ 5/7 of calendar days (weekends removed by ratio, holidays not)
Months and business days are approximations — real months run 28 to 31 days, and the business-day figure removes weekends by ratio but not public holidays. The day count itself is exact.
Worked example
Using the example values — Start Date 2026-08-12, End Date 2026-09-11 — the Date Calculator returns a Days Between Dates of 0 days. It also reports Weeks (0.0), Months (approx) (0.0), Business Days (approx) (0).
Prefer your own numbers? Change any field above and this recomputes instantly.
Key terms
- Calendar days
- Every day in the span, weekends and holidays included.
- Business days
- Weekdays only; this estimates them as 5/7 of the total.
- Average month length
- 30.44 days, i.e. 365.25 ÷ 12, used for the month estimate.
Frequently asked questions
Is the day count exact?
Yes — it's a direct difference between the two dates. The weeks, months and business-day figures derived from it are approximations.
Are holidays removed from business days?
No — the estimate removes weekends by ratio (5/7) but not public holidays, so the true number of working days may be slightly lower.
Why is a month 30.44 days here?
That's the yearly average (365.25 ÷ 12). Using it avoids picking a specific 28–31-day month, at the cost of being approximate for any single month.