9 years before 28 August 2026 is Monday, 28 August 2017
Counting back 9 years from Friday, 28 August, and not counting today itself, the answer is Monday, 28 August 2017. Written out, that is 2017-08-28 in ISO 8601 form, 8/28/2017 in the US month-first format and 28/08/2017 day-first. It falls in ISO week 35 of 2017 and is day 240 of 365, with 125 days of 2017 still to run after it.
How the month end is handled. Today is the 28th of the month and August 2017 has 31 days, so the answer is 28 August. Where the start day number does not exist in the target month — the 29th, 30th or 31st landing in a shorter one — the answer clamps back to the last day of that month rather than rolling over into September. That is the convention every legal and accounting definition of "one month" uses, and it is where our answer legitimately differs from a calculator that adds days instead of months. The rule is written out on the methodology page.
The same span, counted other ways
9 years is 3,287 calendar days here — the exact figure depends on which months the span crosses, which is why we count the calendar rather than multiplying. 3,287 calendar days is 469 weeks and 4 days, about 107.99 months, and 78,888 hours. Counting only Monday to Friday there are 2,349 weekdays and 938 weekend days in it, and after removing 99 US federal holidays that leaves 2,250 business days. If what you actually want is 9 business days rather than 9 years, that is a different date.
Federal holidays inside this span. Observed US federal holidays falling on a weekday inside it: Labor Day on 4 September 2017, Columbus Day on 9 October 2017, Veterans Day on 10 November 2017, Thanksgiving on 23 November 2017, Christmas Day on 25 December 2017, New Year's Day on 1 January 2018, Martin Luther King Jr. Day on 15 January 2018, Presidents' Day on 19 February 2018, Memorial Day on 28 May 2018, Juneteenth on 19 June 2018, Independence Day on 4 July 2018, Labor Day on 3 September 2018, Columbus Day on 8 October 2018, Veterans Day on 12 November 2018, Thanksgiving on 22 November 2018, Christmas Day on 25 December 2018, New Year's Day on 1 January 2019, Martin Luther King Jr. Day on 21 January 2019, Presidents' Day on 18 February 2019, Memorial Day on 27 May 2019, Juneteenth on 19 June 2019, Independence Day on 4 July 2019, Labor Day on 2 September 2019, Columbus Day on 14 October 2019, Veterans Day on 11 November 2019, Thanksgiving on 28 November 2019, Christmas Day on 25 December 2019, New Year's Day on 1 January 2020, Martin Luther King Jr. Day on 20 January 2020, Presidents' Day on 17 February 2020, Memorial Day on 25 May 2020, Juneteenth on 19 June 2020, Independence Day on 3 July 2020, Labor Day on 7 September 2020, Columbus Day on 12 October 2020, Veterans Day on 11 November 2020, Thanksgiving on 26 November 2020, Christmas Day on 25 December 2020, New Year's Day on 1 January 2021, Martin Luther King Jr. Day on 18 January 2021, Presidents' Day on 15 February 2021, Memorial Day on 31 May 2021, Juneteenth on 18 June 2021, Independence Day on 5 July 2021, Labor Day on 6 September 2021, Columbus Day on 11 October 2021, Veterans Day on 11 November 2021, Thanksgiving on 25 November 2021, Christmas Day on 24 December 2021, New Year's Day on 31 December 2021, Martin Luther King Jr. Day on 17 January 2022, Presidents' Day on 21 February 2022, Memorial Day on 30 May 2022, Juneteenth on 20 June 2022, Independence Day on 4 July 2022, Labor Day on 5 September 2022, Columbus Day on 10 October 2022, Veterans Day on 11 November 2022, Thanksgiving on 24 November 2022, Christmas Day on 26 December 2022, New Year's Day on 2 January 2023, Martin Luther King Jr. Day on 16 January 2023, Presidents' Day on 20 February 2023, Memorial Day on 29 May 2023, Juneteenth on 19 June 2023, Independence Day on 4 July 2023, Labor Day on 4 September 2023, Columbus Day on 9 October 2023, Veterans Day on 10 November 2023, Thanksgiving on 23 November 2023, Christmas Day on 25 December 2023, New Year's Day on 1 January 2024, Martin Luther King Jr. Day on 15 January 2024, Presidents' Day on 19 February 2024, Memorial Day on 27 May 2024, Juneteenth on 19 June 2024, Independence Day on 4 July 2024, Labor Day on 2 September 2024, Columbus Day on 14 October 2024, Veterans Day on 11 November 2024, Thanksgiving on 28 November 2024, Christmas Day on 25 December 2024, New Year's Day on 1 January 2025, Martin Luther King Jr. Day on 20 January 2025, Presidents' Day on 17 February 2025, Memorial Day on 26 May 2025, Juneteenth on 19 June 2025, Independence Day on 4 July 2025, Labor Day on 1 September 2025, Columbus Day on 13 October 2025, Veterans Day on 11 November 2025, Thanksgiving on 27 November 2025, Christmas Day on 25 December 2025, New Year's Day on 1 January 2026, Martin Luther King Jr. Day on 19 January 2026, Presidents' Day on 16 February 2026, Memorial Day on 25 May 2026, Juneteenth on 19 June 2026 and Independence Day on 3 July 2026. That is 99 US federal holidays for the business-day count to step over; those days are included in the calendar-day answer above and excluded from the business-day figure. Where a holiday falls at a weekend, federal offices observe it on the adjacent Friday or Monday, and it is the observed date that we skip — the full list and its source are on the holiday sources page.
Monday, 28 August 2017 in the holiday calendar. Listed observance falling on that date: none. Nearest other listed observance: Labor Day on 4 September 2017, 7 days later (count down to Labor Day). The answer falls on a Monday, and the first working day on or after it is 28 August 2017 — so if this is a deadline that has to be met on a working day, that is the practical date. Federal holidays close banks, federal offices and most schools and do not count as business days; the other entries on this calendar are observances, which leave offices open and still count. Approximate lunar and sighting-based dates are listed but are never named as the nearest, because presenting an estimate as a fixed point is exactly what this site undertakes not to do.
Daylight-saving clock changes. US clock changes inside this span: ends on 5 November 2017, starts on 11 March 2018, ends on 4 November 2018, starts on 10 March 2019, ends on 3 November 2019, starts on 8 March 2020, ends on 1 November 2020, starts on 14 March 2021, ends on 7 November 2021, starts on 13 March 2022, ends on 6 November 2022, starts on 12 March 2023, ends on 5 November 2023, starts on 10 March 2024, ends on 3 November 2024, starts on 9 March 2025, ends on 2 November 2025 and starts on 8 March 2026. The calendar date is unaffected — adding whole calendar days cannot be moved by a clock change, which is exactly why this site adds days to the (year, month, day) components rather than adding 86,400,000 milliseconds at a time. What does change is elapsed wall-clock time: the day the clocks go forward is 23 hours long and the day they go back is 25, so the 78,888 hours quoted above is the nominal figure and an hours calculation across this span differs from it by an hour for each transition it crosses. See the time calculator if that is the number you need.
Leap days. 29 February dates inside this span: 29 February 2020 and 29 February 2024. A leap day means the span holds one more calendar day than the same count of years would suggest, and it is the reason 365 days does not always reach the same date next year. A year is a leap year when it divides by four and is not a century year, unless it also divides by 400 — which is why 1900 was not one and 2000 was. The full rule is on the leap year calculator.
The span runs from August 2026 into August 2017, crossing 108 month ends and 9 year ends.
Does today count?
No — and this is where calculators disagree, so it is worth being explicit. On this page day 1 is yesterday, 27 August 2026, and the start date is not included. That gives Monday, 28 August 2017. If your contract, court rule or notice period counts today as day one, the answer you want is one day later: Tuesday, 29 August 2017. Both numbers are on this page deliberately, because re-checking an off-by-one on a second site is the most common reason anyone looks a date offset up twice.
Every convention used above — whether the start date counts, how month ends are clamped, which holidays close an office — is written out on the methodology page, including the business-day rule and the holiday set behind the 2,250-business-day figure above.