Date difference
days = date₂ − date₁Difference364 days
- Weeks52 wk 0 days
- Full months11
- Years1
- Hours8,736
Converters
Dates and time
Date difference, business days, age, time conversion and week number.
Deadlines are counted in calendar days or in business days, and that is usually where the mistakes come from. The calculators give both, along with the ISO 8601 week number, the day of the year and the day of the week — without public holidays, which differ from country to country.
Calculators
6Add or subtract days
date ± n daysResult2026-12-16
- In wordsDecember 16, 2026
- Day of the weekWednesday
- Weeks12.86
- Date − n days2026-06-20
Business days
Monday–Friday between the datesBusiness days22
- Weekend days8
- All days30
- Working hours (8 h)176
Age and days alive
today − date of birthAge36 years
- Days alive13,279
- To birthday235 days
- Day of the week you were bornMonday
- Weeks1,897
Time into units
hours : minutes : secondsTotal165.5 min
- Seconds9,930
- Hours2.75833
- Clock format2:45:30
- Days0.114931
Week number and day of the year
the ISO 8601 standardWeek38 / 2026
- Day of the year260 of 365
- Day of the weekFriday
- QuarterQ3
- Leap yearno
Tables and cheat sheets
1Months, quarters and days of the year
for a common year of 365 days| Month | Days | Quarter | First day of the year | Last day of the year |
|---|---|---|---|---|
| January | 31 | Q1 | 1 | 31 |
| February | 28 (29) | Q1 | 32 | 59 |
| March | 31 | Q1 | 60 | 90 |
| April | 30 | Q2 | 91 | 120 |
| May | 31 | Q2 | 121 | 151 |
| June | 30 | Q2 | 152 | 181 |
| July | 31 | Q3 | 182 | 212 |
| August | 31 | Q3 | 213 | 243 |
| September | 30 | Q3 | 244 | 273 |
| October | 31 | Q4 | 274 | 304 |
| November | 30 | Q4 | 305 | 334 |
| December | 31 | Q4 | 335 | 365 |
Worked examples with full solutions
1A 30 business day deadline
A contract signed on September 1, 2026. The deadline is 30 business days — when does it fall?
- Count from the next business day
start: Wednesday, September 2, 2026 - 30 business days is 6 full working weeks
6 weeks minus 2 days = 40 calendar days - Add 40 days to September 2
Sep 2 + 40 days = October 12, 2026 - Check it with the business day calculator
there are exactly 30 business days between Sep 2 and Oct 12
Answer: The deadline falls on Monday, October 12, 2026 — provided no public holiday lands in that period.
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