About Date Difference
Date Difference tells you how much time sits between any two dates — broken down into years, months and days, plus the totals in weeks, days, hours, and minutes. There's a workday counter that excludes weekends, and an add/subtract mode that takes a starting date plus a duration and tells you the resulting date. Useful for project deadlines, contract dates, pregnancy tracking, anniversary planning, and historical research.
- No uploads
- Browser-only
- Works offline
- 100% free
How it works
- 1
Pick two dates
Type or pick a start and end date. Times before 1900 and decades into the future both work.
- 2
Read the breakdown
Calendar diff (Y/M/D), plus totals in weeks, days, hours, minutes — and a workday count if you need to exclude weekends.
- 3
Switch to add/subtract
Toggle the second mode: enter a start date and a +/– duration (e.g. 90 days, 6 months) to get the resulting date.
Inclusive versus exclusive: the off-by-one that costs money
The single biggest source of date-math errors is whether both endpoints count. Exclusive counting (the default in arithmetic) measures the gap: from the 1st to the 4th is 3 days, because you subtract. Inclusive counting adds one to count the days themselves: the 1st, 2nd, 3rd and 4th is 4 days. Neither is 'right' — they answer different questions. 'How many nights in the hotel?' is exclusive. 'How many days am I on holiday, counting the day I arrive and the day I leave?' is inclusive.
Contracts and statutes are explicit about this for a reason. A '30 days notice' clause usually means 30 clear days, excluding the day notice is served — so served on the 1st, the period runs from the 2nd. Court deadlines, returns windows and visa durations frequently say 'including the date of entry'. When the wording matters, read it literally and set the tool to match; an off-by-one here is the difference between filing on time and filing late.
Business days versus calendar days
A calendar-day count treats every day equally. A business-day count skips weekends, and often public holidays, because that's how delivery estimates, payment terms and SLAs are written. The two diverge fast: 10 business days is two full weeks of weekends removed — 14 calendar days — and longer still if a bank holiday lands inside the span.
Holidays are the hard part, and they are not universal. England, Scotland and Northern Ireland keep different bank-holiday calendars; the US federal list differs again; many firms add their own closure days. No tool can know which calendar your contract means, so treat a business-day figure as an estimate and confirm the specific non-working days that apply to your agreement.
| Phrase you'll see | Usual meaning | Watch out for |
|---|---|---|
| "within 30 days" | Calendar days, exclusive of the start date | Whether a deadline on a weekend rolls to Monday |
| "30 clear days" | Exclude both the first and last day | Easy to under-count by two days |
| "5 business days" | Weekdays only, weekends skipped | Which country's public holidays count |
| "net 30" | Payment due 30 calendar days after invoice date | Invoice date vs. receipt date as the start |
| "by end of next week" | Ambiguous — agree a real date | Different people picture different weeks |
When stakes are real, replace any of these phrases with an explicit calendar date in writing.
Real uses and the limits of a span
- Notice and probation periods: count from the day after the trigger event unless the wording says otherwise.
- Payment terms (net 15 / net 30 / net 60): the clock almost always starts at the invoice date, not the day the work finished.
- Returns and cooling-off windows: usually inclusive of the day you received the item — count the delivery date as day one.
- Age and anniversaries: this tool counts a raw span; for years-months-days broken out the way a person reads age, use Age Calculator.
- Exact durations down to seconds, or converting a date to a Unix timestamp, are a different job — the Timestamp Converter handles those.
Frequently asked questions about Date Difference
Are weekends and holidays excluded from the workday count?
Weekends (Saturday and Sunday) are always excluded from the workday total. National holidays are not — they vary by country and region. For US/UK/IN-specific workday counts with holidays excluded you'll need to subtract the holidays manually from the result.
Does it handle daylight saving time?
The Y/M/D breakdown isn't affected by DST since it counts calendar days. The hour and minute totals are computed in your local timezone and will reflect the one missing or extra hour at DST transitions — usually a non-issue for date ranges spanning multiple days.
Can I compute things like '90 days from today'?
Yes — that's exactly what the add/subtract mode is for. Enter today's date, type '+ 90 days', and the resulting date appears. Useful for contract deadlines, return windows, and waiting-period calculations.
Privacy, offline use, browser support, and pricing questions are answered on the site-wide FAQ.