One hundred twenty days is 17 weeks and one day, so the end date lands one weekday past today. It is the closest any round day count gets to a calendar span: four calendar months run 120 to 123 days, so 120 days is between zero and three days short of four months.
That near-match is useful and slightly dangerous. It means 120 days can be exactly four months, but only sometimes.
When 120 days is exactly four months
Four consecutive calendar months total 120, 121, 122 or 123 days. The count hits 120 exactly only when the window contains a 28-day February:
- 1 January to 1 May is 120 days in a non-leap year, because January, February, March and April total 31 + 28 + 31 + 30
- 1 November to 1 March is also 120 days, at 30 + 31 + 31 + 28
Every other four-month window is longer. A window through July and August, the two consecutive 31-day months, runs the full 123.
So "120 days" and "four months" agree in winter and diverge by up to three days in summer. In a leap year even the February windows run 121. When a contract writes both, the days version governs, and it is worth checking which one a renewal date was actually built from.
Where 120-day deadlines appear
One hundred twenty days is used where four months is meant but a fixed day count is wanted:
- Bankruptcy (US): a Chapter 11 debtor has an exclusive 120-day period after filing in which only it may propose a plan of reorganisation, and courts can extend it
- Trade finance: 120-day usance terms on letters of credit, and 120-day deferred payment arrangements with overseas suppliers
- Employment: 120-day probationary periods, common in public-sector and unionised roles where 90 days is too short to complete a review cycle
- Government: 120-day public comment and consultation periods on proposed rules
- Training: a 120-day block for anything needing four distinct monthly phases, such as marathon or powerlifting preparation
Because 120 is one more than a whole number of weeks, a 120-day deadline set on a Friday lands on a Saturday. For legal deadlines, confirm how the governing rule handles a weekend landing rather than assuming it rolls forward.
Counting 120 days accurately
Three ways to check the count, in order of reliability:
- In weeks: 17 weeks takes you to the same weekday, then add one day
- In months: about four, but verify against the calendar since the true span is 120 to 123 days
- In business days: 120 calendar days contain 85 or 86 weekdays, 86 from a Sunday through Thursday start and 85 from a Friday or Saturday start
Subtract public holidays for a working figure. A 120-day US window normally contains three or four federal holidays, so 82 to 83 working days is realistic.
If a document specifies 120 business days instead, that is 166 to 168 calendar days, about five and a half months. That is a 46-day difference from the calendar reading, the largest gap of any span on this site.
Frequently Asked Questions
Is 120 days the same as 4 months?
Almost. Four calendar months run 120 to 123 days, and the total is exactly 120 only when the window contains a 28-day February, such as 1 January to 1 May in a non-leap year. Every other four-month window is one to three days longer.
How many weeks is 120 days?
17 weeks and 1 day. Since 120 is one more than a multiple of seven, the end date falls one weekday past your starting weekday, so 120 days from a Monday is a Tuesday.
How many business days are in 120 calendar days?
85 or 86 before public holidays: 86 from a Sunday through Thursday start and 85 from a Friday or Saturday start. Allowing for three or four US federal holidays, 82 or 83 working days is the practical figure.
What is the 120-day rule in Chapter 11?
After filing for Chapter 11, the debtor has an exclusive 120-day period in which only it may file a plan of reorganisation. The court can extend that period, and once it lapses creditors and other parties may propose competing plans.