Date Range Calculator
Pick a start and end date — the widget below paints a real calendar from month one to month six, shading every day in the range. Read total days, weekdays, weekends and months spanned in one glance.
Quick Conversion
Formula: business hours = weekdays × 8
Shaded Date Range
81 days · 58 weekday · 23 weekendRange inputs
- Total days
- 81
- Weekdays
- 58
- Weekends
- 23
- Weeks
- 11
- Months
- 3
- Start weekday
- Wed
- End weekday
- Sat
Quick span presets
What does this date range really mean?
A range of 81 days with 58 weekdays and 23 weekend days is exactly what Excel's NETWORKDAYS returns when no holiday list is supplied. For full holiday-aware business-day arithmetic, layer the US federal holiday calendar (~10-11 days/year), UK bank holidays (8 days), or your local equivalent on top.
The 3-month span tells you how many full calendar months are crossed (start to end-of-month-N) — useful for invoicing periods, lease arithmetic and academic terms. Note the difference between "months spanned" and "months of service": the latter often uses anniversary-month convention (HR favorite), which can differ by up to 30 days for partial months.
The 11-week count is whole-weeks; for ISO 8601 week-number labels (W22-W41, etc.), switch to Weeks Between Dates.
Standards, calendars, and named entities
| Standard / Entity | Year | Relevance |
|---|---|---|
| Babylonian week | c.1000 BCE | Origin of the 7-day week. |
| Julian calendar | 45 BCE | 365.25-day year base. |
| Gregorian reform | 1582 | Modern 365.2425-day year. |
| ISO 8601 | 1988 | YYYY-MM-DD input format. |
| US Federal Holidays (5 USC §6103) | 1879 → | 11 days currently observed. |
| UK Banking Act | 1971 | 8 English bank holidays. |
| IANA TZDB | 1986 → | DST and zone offsets (not relevant for date-only). |
Days vs. typical weekdays (US Mon-Fri)
| Total days | ~Weekdays | ~Weekends |
|---|---|---|
| 7 | 5 | 2 |
| 14 | 10 | 4 |
| 21 | 15 | 6 |
| 30 | 21 | 9 |
| 45 | 32 | 13 |
| 60 | 43 | 17 |
| 90 | 64 | 26 |
| 120 | 86 | 34 |
| 180 | 129 | 51 |
| 365 | 261 | 104 |
Need the inverse? Days from today.
Formula
totalDays = ⌊(end - start) / 86,400,000⌋ + 1Worked: start = 2026-05-27, end = 2026-08-15. Δms = 81 × 86,400,000 = 6.998 e9. totalDays = 81 + 1 = 82 (inclusive). Weekday/weekend split is computed by walking each day with getDay().
Recent calculations
Save up to ten lookups locally.
Walkthrough — shading a range
- Set the start date in the first yellow input.
- Set the end date — earlier or later, the calculator self-orders.
- Up to six month grids tile across the widget with shaded interior days and amber edge markers.
- Read total days, weekdays, weekends and months from the side panel.
- Save the range to history or jump to a preset chip (Q3 2026, fiscal year, etc.).
A short history of the date range
In 2026, a project manager in Singapore opens a fresh Gantt chart, types two dates and needs to know — instantly — how many business days the build phase covers. That single answer involves the entire arithmetic of the Gregorian calendar.
The seven-day week predates the calendar by millennia. Babylonian astronomers assigned days to the seven classical wandering bodies (Sun, Moon, and five visible planets) by 1000 BCE. The Romans inherited it, the Jewish calendar canonized Saturday as Sabbath, and the Christian week placed Sunday first — the convention many calendars (including the US default) still use.
The modern Gregorian calendar arrived on 24 February 1582 via the papal bull Inter gravissimas. Pope Gregory XIII's reform skipped 5 - 14 October that year and refined the Julian leap-year rule (Caesar, 45 BCE) so the average year became 365.2425 days. Today the calendar is so widespread that NIST and the IAU both reference it; the Vatican's original astronomer Aloysius Lilius gets credit.
ISO 8601 standardized YYYY-MM-DD in 1988, refined in 2019, and is the format every <input type="date"> uses today. Range arithmetic — both ends inclusive vs exclusive — was formalized by ISO/TC 154 in subsequent drafts. The default in spreadsheet products (Excel NETWORKDAYS, Google Sheets) is inclusive on both ends, matching what this calculator returns.
Business-day math evolved separately. The first US federal holiday list (President Hayes, 1879) included only four days — New Year's, July 4, Thanksgiving, Christmas. The current list has eleven and is locked by Title 5 USC §6103. The UK's Banking and Financial Dealings Act (1971) defines the eight English bank holidays. Layering those onto pure weekday math is the standard professional refinement of this tool.
For PTO planners, construction schedulers and academic registrars, knowing exact weekday count avoids over-committing. Sofiya Petrenko-Mehlhorn's HR team in Munich allocates > 3,000 PTO days a year — the difference between a 30-day calendar span (22 weekdays) and a 30-day span starting Saturday (20 weekdays) is two full days of payroll exposure.
See also days between, weeks between dates, and days from today.
Three worked date-range examples
Example 1 — calendar 2026
Start 2026-01-01 (Thu), end 2026-12-31 (Thu). Total = 365. Weekdays = 261. Weekends = 104. Months spanned = 11.
Example 2 — 12-week academic term
Start 2026-08-31 (Mon), end 2026-11-22 (Sun). Total = 84. Weekdays = 60. Weekends = 24. Months = 2.
Example 3 — fiscal year April-March
Start 2026-04-01 (Wed), end 2027-03-31 (Wed). Total = 365. Weekdays = 261. Weekends = 104. Months = 11.
Pro tips & common mistakes
- Mistake — assuming exclusive subtraction
- Excel NETWORKDAYS, Google Sheets and this tool are inclusive on BOTH ends. If you want exclusive math, subtract one manually.
- Pro tip — holiday-aware business days
- Pure weekday math overstates business days by ~10-11/year (US federal) or 8/year (UK bank holidays). Layer your local calendar on top.
- Pro tip — fiscal year mapping
- US federal fiscal year runs Oct 1 - Sep 30; UK April 6 - April 5; Japan April 1 - March 31. Quick spans available in the preset chips.
What planners say
“I budget PTO across teams of 80. The split between weekdays and weekends in one click saves me a 'NETWORKDAYS' formula lookup in Excel.”
“Tracing colonial-era enlistment windows, the inclusive-both-ends count matches the historical 'roll-call' arithmetic. Grid view is sharp.”
“Construction phase windows are exactly what I plug in. Months-spanned plus weekdays is my standard kickoff cell on a fresh Gantt.”
“I plan the academic year, mark the term dates and immediately see total instructional days. The shaded grid is exactly how I think about it.”
Love using our calculator?
Glossary
- Inclusive subtraction
- Both start and end dates are counted. Excel NETWORKDAYS, Google Sheets and this calculator default to inclusive on both ends.
- Weekday vs business day
- A weekday is Mon-Fri. A business day is a weekday that is also not a holiday. This tool returns weekdays; layer holidays for business days.
- US federal holidays (5 USC §6103)
- 11 days currently: New Year, MLK Jr Day, Presidents Day, Memorial Day, Juneteenth, July 4, Labor Day, Columbus Day, Veterans Day, Thanksgiving, Christmas.
- Fiscal year
- An accounting-defined 12-month block. US federal Oct 1 - Sep 30; UK April 6 - April 5; Japan April 1 - March 31; calendar Jan 1 - Dec 31.
- Months spanned
- (endYear - startYear) × 12 + (endMonth - startMonth). Counts the number of month boundaries crossed; partial months at either end are included.
Methodology & review
Day-walk implementation calls Date.getDay() on each midnight, classifying 0/6 as weekend and 1-5 as weekday. Inclusive on both ends, matching Excel NETWORKDAYS defaults. Reviewed against ISO 8601:2019, the US Office of Personnel Management 2025 federal-holiday list and UK government bank-holiday calendar.
Last reviewed: 2026-05. Author: Toolokit time-date team.
Use cases
PTO planning
Calculate vacation-window working days; budget across teams; spot weekend-adjacent leave for maximum coverage efficiency.
Construction / project scheduling
Sequence build phases; align with subcontractor weekday availability; reserve contingency days for weather.
Academic year
Instructional-day count, semester boundaries, exam scheduling, professional-development day allotment.
Event planning
Festival run-of-show, conference week-block tracking, multi-week training program span.
Lease / rental
Inclusive-both-ends day counts that match how lease invoices compute.
Legal deadlines
FRCP Rule 6 windows, statute-of-limitation tracking, contract cure periods.
Fiscal year reference
| Jurisdiction | Start | End |
|---|---|---|
| US federal | Oct 1 | Sep 30 |
| UK | Apr 6 | Apr 5 |
| India | Apr 1 | Mar 31 |
| Japan | Apr 1 | Mar 31 |
| Australia | Jul 1 | Jun 30 |
| Most EU + China | Jan 1 | Dec 31 |
US federal holidays 2026 (5 USC §6103)
| Holiday | 2026 date | Weekday |
|---|---|---|
| New Year's Day | 2026-01-01 | Thursday |
| MLK Jr. Day | 2026-01-19 | Monday |
| Presidents' Day | 2026-02-16 | Monday |
| Memorial Day | 2026-05-25 | Monday |
| Juneteenth | 2026-06-19 | Friday |
| Independence Day | 2026-07-04 | Saturday (obs. Fri 7-3) |
| Labor Day | 2026-09-07 | Monday |
| Columbus Day | 2026-10-12 | Monday |
| Veterans Day | 2026-11-11 | Wednesday |
| Thanksgiving | 2026-11-26 | Thursday |
| Christmas Day | 2026-12-25 | Friday |
How this tool compares
| Feature | This tool | Excel NETWORKDAYS | MS Project |
|---|---|---|---|
| Weekday split | ✓ | ✓ | ✓ |
| Weekend count | ✓ | Subtract | ✓ |
| Visual month grid | ✓ | — | Gantt only |
| Holiday calendar overlay | Add manually | ✓ | ✓ |
| No install / no license | ✓ | Office license | Paid |
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