Are start and end dates inclusive?

By default the start date is excluded and the end date is included, matching the common "net N days" billing convention. You can switch to inclusive on both ends for legal-deadline math.

How are holidays defined?

By date. The calculator doesn't know which holidays apply where, so you supply the list (or pick a preset). Religious and floating holidays are baked into presets where applicable.

Do holiday lists leave my browser?

No. Everything runs locally; pasted holiday lists are never transmitted.

weekdays · weekends · holidays · live

Count business days between dates

Q: What about half-days?

Not modeled. Each date is either a working day or not. For half-day awareness, treat half-days as full and apply a fractional multiplier downstream.

Sums weekdays between two inclusive dates, then subtracts a custom holiday list. Output breaks down the total, weekends, and excluded holidays.

Business Days Calculator

Business

—

weekdays - holidays

Total

—

inclusive

Weekends

—

Sat + Sun

Holidays

—

excluded

input · holidays (YYYY-MM-DD per line)

output · breakdown

Pick start and end dates.

Quick Start

How the count works

We iterate every day between start and end (inclusive). Each Sat/Sun goes to weekends; each ISO match in your holiday list goes to holidays; everything else is a workday.

01
Pick start + end
Inclusive — both endpoints count. End must be on or after start.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
inputISO 8601RFC 3339epochlive
start · timestampend · ISO
```
2026-01-01
2026-01-31
```
loaded · ISO 8601zone · ready
02
Paste holidays
One ISO date per line — copy-paste from your HR site or a public holiday source.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via Intl.DateTimeFormat.
holidaysUTC mathIntlDST-safelive
list · optionsyyyy-mm-dd · live
```
2026-01-01
2026-12-25
```
options applied · UTCDST-safe
03
Iterate days
Sat/Sun = weekend; matched ISO = holiday; rest = workday.
Output respects the chosen timezone offset (Z vs +05:30) and pads digits per ISO conventions so sorts stay chronological.
countoffsetzone-awaresortablepadded
loop · computedday · ready
```
dow: 0/6 = w/e
```
computed · instantsortable
04
Read the breakdown
Business days are the headline; totals, weekends, holidays sit underneath.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
outclipboardno oracledeterministicclient-side
✓ · copiedready · done
```
✓ Copied
```
shipped · ready to shipsuccess

Pro tips

Time math without DST landmines

Always store UTC

Convert to local for display only. UTC storage avoids DST jumps and timezone drift in databases.

Watch leap seconds

POSIX time doesn’t count leap seconds; some systems do. Don’t use timestamps for sub-second precision across boundaries.

Prefer Temporal eventually

The Date API has many quirks. Temporal is shipping in modern engines and handles zones correctly.

Cron is timezone-tricky

Cron expressions run in the daemon’s local zone unless told otherwise. Pin a TZ explicitly for predictable runs.

ISO 8601 sorts naturally

YYYY-MM-DDTHH:mm:ss sorts correctly as a string. Don’t use US-style MM/DD/YYYY for anything machine-readable.

Beware Y2K38

Signed 32-bit Unix timestamps overflow in 2038. Use 64-bit storage end-to-end for long-lived systems.

Use Cases

When to count business days

Contracts, SLAs, payroll, leave.

Contract delivery

"5 business days" SLAs land on real dates with holidays excluded. Math runs in UTC under the hood to dodge DST jumps — local time is only for display. That means scheduling logic and date diffs survive March / November fall-back without the classic off-by-one-hour bug.

DST-safe

Payroll

Working-day counts feed accrual calculations. Browser clock is the only source — no external time server, no privacy leak, no rate limit. Pair with NTP-synced server time for high-accuracy use cases, but for human-scale work the browser clock is plenty.

UTC-correct

Leave planning

How many working days does a 2-week holiday eat? ISO 8601 output sorts naturally as strings, perfect for filenames (report-2026-01-15.pdf) and log lines that need chronological ordering without parsing. Drop into S3 keys for free time-bucketing.

ISO-sortable

Court deadlines

Legal filings often measure in business days. Pairs cleanly with cron, scheduled tasks, and timestamped log analysis. The tool's output drops directly into APScheduler, Linux cron, or GitHub Actions schedule expressions without re-formatting.

spec-grade

Project sizing

Estimates over a span need workday counts, not raw days. Output respects the chosen timezone offset (Z vs +05:30) so REST APIs and database TIMESTAMP WITH TIME ZONE columns round-trip cleanly. No ambiguity between "noon UTC" and "noon local".

zone-aware

International ops

Different countries have different holiday calendars — paste yours. Confirms the difference between epoch seconds (10 digits) and milliseconds (13 digits) before you commit code that mis-multiplies by 1000 — a classic bug in cross-language time handling.

i18n

FAQ

Frequently asked questions

Inclusive of both endpoints?

Yes. Start = Jan 1, End = Jan 1 counts as 1 day. Subtract 1 if your contract excludes the start.

What defines a weekend?

Saturday (6) and Sunday (0) — the Christian / Western default. For Middle East ops, you'd need a custom rule.

How do I get a holiday list?

Most HR systems export one; public-holiday APIs (Nager.Date, date.nager) provide them too. Paste the ISO dates here.

What about half-days?

Each day is one whole unit — no half-day weighting. Subtract manually if a half-day matters.

Is anything sent to a server?

No — the count runs locally in your browser tab.

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