To convert days to months, divide by 30.44, the length of an average month. That makes 90 days about 2.96 months, 120 days about 3.94 months and 180 days about 5.91 months. In everyday speech they're "3, 4 and 6 months", but on a real calendar they usually fall a few days short, and for contracts and deadlines those few days matter.
Days to months conversion table
| Days | Months (average) | Weeks | Roughly |
|---|---|---|---|
| 30 | 0.99 | 4.3 | 1 month |
| 45 | 1.48 | 6.4 | 1½ months |
| 60 | 1.97 | 8.6 | 2 months |
| 90 | 2.96 | 12.9 | 3 months (one quarter) |
| 100 | 3.29 | 14.3 | 3 months and 9 days |
| 120 | 3.94 | 17.1 | 4 months |
| 150 | 4.93 | 21.4 | 5 months |
| 180 | 5.91 | 25.7 | 6 months |
| 200 | 6.57 | 28.6 | 6½ months |
| 270 | 8.87 | 38.6 | 9 months |
| 365 | 11.99 | 52.1 | 1 year |
Why 90 days isn't quite 3 months
Three calendar months contain between 89 and 92 days, depending on which months you cross:
- January 1 to April 1, 2027: 90 days (February is short).
- July 1 to October 1, 2027: 92 days (July and August both have 31).
- November 1, 2026 to February 1, 2027: 92 days.
So "90 days" and "3 months" can end on different dates. Counting 90 days from July 1, 2027 lands on September 29, two days before the three-month mark of October 1. The same goes for 180 days, which typically ends 2–4 days before the six-month mark.
Real dates for common periods
Counting from a few sample start dates (day 0 is the start date):
| Start | +90 days | +120 days | +180 days |
|---|---|---|---|
| October 5, 2026 | January 3, 2027 | February 2, 2027 | April 3, 2027 |
| January 4, 2027 | April 4, 2027 | May 4, 2027 | July 3, 2027 |
| June 1, 2027 | August 30, 2027 | September 29, 2027 | November 28, 2027 |
For your own start date, use 90 days from today, 120 days from today or 180 days from today.
When "days" vs "months" matters
- Probation periods: a "90-day probation" ends on a specific calendar date, which can differ from "three months" by a couple of days. Check your offer letter for which one it says.
- Return and warranty windows: retailers usually count calendar days from purchase or delivery.
- Travel and visas: many entry rules use day counts. The Schengen area, for instance, allows up to 90 days in any 180-day period, counted day by day, not by months. Always check the official government source for your situation.
- Medication supplies and insurance: pharmacies often fill "90-day supplies", and a quarter of a year in benefits terms is usually 3 calendar months.
- Legal and tax deadlines: statutes say exactly whether they count days or months, and whether weekends count. See our guide to 30-, 60- and 90-day deadlines.
The formula
- Months = days ÷ 30.44 (or ÷ 30.42 for a 365-day year)
- Days = months × 30.44
- Weeks = days ÷ 7
Dividing by 30 is a fine rough estimate, but it overstates the months a little over long periods: 365 ÷ 30 = 12.2 "months". If you're working in weeks, see weeks to months.
Between two specific dates? The date duration calculator shows the gap in months and days, total days and weeks, and the number of business days.
Frequently asked questions
Is 90 days 3 months?
Approximately. 90 days is 2.96 average months; three calendar months range from 89 to 92 days.
How many months is 120 days?
About 3.94 months, or roughly 4 months minus a couple of days.
How many months is 180 days?
About 5.9 months. Six calendar months are 181 to 184 days, so 180 days ends slightly earlier.
How many months is 60 days?
About 2 months (1.97), or 8 weeks and 4 days.