Date Difference Calculator: Days and Workdays

The Calculate panel of the date tool does two jobs on one date engine: it measures a span between two fixed dates and shifts one date by calendar units. Date difference splits a span into years, months and days and prints a total day count; Add/subtract dates moves a base date by years, months and days. Business days counts workdays and days off across a range and steps a base date ± N whole workdays, under the Monday–Friday rule or CN statutory holidays with make-up days. Everything runs in your browser.

Updated 2026-10-01Reviewed by CalcX Editorial Team4 sources3 min read

How to use it

Measure a difference.Enter a Start date and an End date; the Difference card reads Years, Months, Days and a Total line. The earlier date leads whichever field it was typed in.
Shift one date.Switch to Add/subtract dates, pick Add or Subtract, then set the base date, years, months and days. The Result date card shows the landing day.
Count business days.The From/To row reports Total days (incl.), Workdays and Days off. The CN statutory holidays toggle switches between statutory holiday data and the plain Monday–Friday rule.
Step whole workdays.Give the ± N workdays box a base date and a count; the Result shows the Nth workday in that direction, and Export .ics drops it into a calendar as an all-day event.

Worked examples

Fixed inputs, read from the panel:

You enter	The panel reads
Difference: 2026-01-31 → 2026-03-01	0 y, 1 m, 1 d; Total: 29 days
Difference: 2026-03-01 → 2026-01-31	the same 1 m, 1 d split and the same 29 days
Add 2026-08-31 + 6 months	2027-03-03
Subtract 2026-03-31 − 1 month	2026-03-03
Business 2026-04-29 → 2026-05-06, holidays on	Total days (incl.) 8, Workdays 3, Days off 5
Same range, Mon–Fri rule	Workdays 6, Days off 2
Base 2026-04-30, +1 workday, holidays on / off	2026-05-06 / 2026-05-01
Base 2026-05-11, −1 workday, holidays on	2026-05-09

Two readings surprise people. First, the year-month-day split borrows the days after the start date from the month before the end date and clamps at that month's length: 31 January to 1 March reads 1 month and 1 day even though 29 days have passed, because February 2026 has only 28 days — trust the Total line for the span. Second, Labour Day 2026 bends the workday calendar: with CN holidays on, one workday after 30 April is 6 May, while one workday before Monday 11 May is Saturday 2026-05-09, a make-up workday.

Limits

Counting caps.: Workdays and days off stop beyond 3,700 days: 2026-01-01 → 2037-01-01 shows Total 4,019, but Workdays reads range too large and Days off a dash. The ± N field accepts whole workdays up to 2,500 in either direction.
Holiday data.: CN statutory days off and make-up days cover 2001 onward; outside that window the Monday–Friday rule applies, and 2026-05-09 counts as a workday.
What it does not do.: It counts whole calendar days only — there is no hour or minute input and no zone handling. For a clock-accurate span to a fixed target use Countdown & Age; for the same instant in other zones use World Clock.

Where it helps

Payroll and invoicing windows

A supplier contract runs from 2026-04-29 to 2026-05-06. The business row returns 3 workdays and 5 days off, so only three dates in that window are billable working days.

Planning around holiday blocks

Before booking leave, put the intended block into From/To with CN holidays on: the Days off count shows the dates you actually need to book, and the ± N stepper finds the first day back at work.

References

ISO, ISO 8601-1:2019, Date and time — Representations for information interchange, iso.org （访问日期：2026-10-01）— date and duration notation.
Wikipedia, Gregorian calendar （访问日期：2026-10-01）— month lengths and the leap rule behind the length clamps.
Wikipedia, Public holidays in China （访问日期：2026-10-01）— statutory days off and make-up workdays.
Wikipedia, Working time （访问日期：2026-10-01）— the Monday–Friday week used when holiday data is off.