Days to Months Calculator
Enter a number of days to convert it to months in seconds. You get the total fractional months, a breakdown into whole years, whole months, and leftover days, and the reverse conversion (months back to days). Choose between the standard Gregorian average (30.44 days per month), the Julian average (30.4375), or a simple 30-day month for quick estimates.
How to convert days to months
To convert a number of days to months, divide by the average number of days per month. The most accurate everyday value is the Gregorian average: 365.2425 days in a year divided by 12 months gives 30.436875 days per month. So months = days / 30.436875. For 180 days: 180 / 30.436875 = 5.9137 months. The simple 30-day shortcut is fine for quick mental arithmetic and gives 180 / 30 = 6.0 months exactly.
How to convert months to days
To reverse the conversion, multiply the number of months by the average days per month. Using the Gregorian average: days = months x 30.436875. So 6 months x 30.436875 = 182.62 days. One calendar year (12 months) averages 365.2425 days, one quarter (3 months) averages 91.31 days, and one half-year (6 months) averages 182.62 days.
Breaking days into years, months and leftover days
For longer spans it helps to decompose the total into whole years, whole months, and leftover days. For example, 500 days: divide by 365.2425 to get 1 whole year (365.24 days), subtract to get 134.76 days left, divide by 30.44 to get 4 whole months (121.75 days), and the remainder is about 13 leftover days. So 500 days = 1 year, 4 months, 13 days. This calculator does all three steps automatically.
Which days-per-month value should you use?
The Gregorian average (30.4369 days) is the right choice for most purposes because it reflects the actual length of the civil calendar used worldwide. The Julian average (30.4375) is marginally different and relevant for historical dating. The simple 30-day month is convenient for contract durations, payment terms, and back-of-envelope estimates where a round number is preferred. None of these replaces a date calculator for finding an exact future date, because real calendar months vary from 28 to 31 days.
Days in each calendar month
| Month | Days (standard year) | Days (leap year) |
|---|---|---|
| January | 31 | 31 |
| February | 28 | 29 |
| March | 31 | 31 |
| April | 30 | 30 |
| May | 31 | 31 |
| June | 30 | 30 |
| July | 31 | 31 |
| August | 31 | 31 |
| September | 30 | 30 |
| October | 31 | 31 |
| November | 30 | 30 |
| December | 31 | 31 |
Standard calendar month lengths. February has 29 days in a leap year.
Frequently asked questions
How many months is 30 days?
Using the Gregorian average (30.4369 days per month), 30 days equals about 0.9856 months, so just under one full month. If you use the simple 30-day convention, 30 days equals exactly 1 month. The small difference matters for precise calculations but is negligible for everyday use.
How many months is 90 days?
Ninety days equals about 2.958 months using the Gregorian average (90 / 30.4369), or exactly 3 months if you use the 30-day simple convention. A calendar quarter is nominally 3 months, but the actual day count varies (Q1 = 90 or 91 days, Q2 = 91 days, etc.).
How many months is 180 days?
One hundred and eighty days is approximately 5.914 months using the Gregorian average (180 / 30.4369). In round terms, 180 days is often treated as 6 months (half a year), which is accurate with the 30-day simple month convention.
How many days is 6 months?
Six months equals approximately 182.62 days using the Gregorian average (6 x 30.4369). In practice, the exact count depends on which six months: a January-June span (non-leap) has 181 days, while a July-December span has 184 days.
Why does the number of days per month vary?
Calendar months were set by historical convention rather than astronomy. January, March, May, July, August, October, and December each have 31 days. April, June, September, and November have 30 days. February has 28 days in a standard year and 29 in a leap year (every 4 years, with exceptions for century years). The average works out to about 30.44 days per month.
What is the difference between a Julian and Gregorian month?
The Julian calendar assumes a year is exactly 365.25 days (one leap day every 4 years with no exceptions), giving 365.25 / 12 = 30.4375 days per month. The Gregorian calendar corrects this slightly to 365.2425 days (skipping leap years on century years not divisible by 400), giving 30.436875 days per month. The difference is tiny: about 0.0006 days per month, or about 11 minutes per year.