What this calculator does
Days to months is a common conversion for anything measured in an odd number of days, a pregnancy milestone, a recovery period, a subscription term, that is easier to picture in months. Because calendar months run from 28 to 31 days, an exact conversion needs an average month length rather than a fixed 30 or 31.
This calculator converts days to months or months to days, both directions, using 30.4375 days per month, the average that falls out of the 365.25-day year divided evenly across 12 months. The equivalent in years is shown alongside.
The formula
Dividing a number of days by 30.4375 gives the equivalent in months, using the average calendar month length. Multiplying a number of months by 30.4375 converts back to days. The 30.4375 figure comes from the 365.25-day average year divided by 12.
| Term | Meaning |
|---|---|
| Day | A 24-hour period, the base unit this conversion works from. |
| Month | A calendar month; this calculator uses the 30.4375-day average across all twelve months and leap years. |
| 30.4375 | The average number of days in a calendar month, equal to 365.25 (the average year) divided by 12. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The value to convert, either a number of days or a number of months, depending on the direction chosen below. |
| Convert | Choose whether to convert days to months, or months to days. |
When to use it
Answering how many days is 6 months
A duration given in months, such as a 6-month lease or notice period, converts to an approximate day count for scheduling purposes.
Converting a day count to months for a milestone
A figure such as 180 days since a surgery, a launch or a start date converts to months for a more natural way of describing progress.
Estimating a subscription or trial length
A trial or subscription period quoted in days converts to months to compare against a plan billed monthly.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Days to months, for common day counts
A range of day counts, each converted to months and years.
| Days | Months | In years |
|---|---|---|
| 30 | 0.99 mo | 0.082 yr |
| 60 | 1.97 mo | 0.164 yr |
| 90 | 2.96 mo | 0.246 yr |
| 180 | 5.91 mo | 0.493 yr |
| 270 | 8.87 mo | 0.739 yr |
| 365 | 11.99 mo | 0.999 yr |
Months to days, for common month counts
A range of month counts, each converted to days.
| Months | Days | In years |
|---|---|---|
| 1 | 30.4 days | 0.083 yr |
| 3 | 91.3 days | 0.250 yr |
| 6 | 182.6 days | 0.500 yr |
| 9 | 273.9 days | 0.750 yr |
| 12 | 365.3 days | 1.000 yr |
| 18 | 547.9 days | 1.500 yr |
Questions
How many days is 6 months?
About 182.6 days, using the 30.4375-day average month (6 × 30.4375). A rough rule of "30 days per month" would undercount by a few days over a 6-month span.
How many months is 180 days?
About 5.91 months, from 180 ÷ 30.4375, just under the round figure of 6.
How many months is 90 days?
About 2.96 months, from 90 ÷ 30.4375, just under 3.
Why isn't a month simply treated as 30 days?
Calendar months actually run from 28 to 31 days, so a flat 30-day assumption drifts noticeably over several months. Using the 30.4375-day average, derived from the 365.25-day year, keeps the conversion accurate over longer spans.
For the related conversion at the year scale, see the days to years calculator. For converting weeks and months instead, see the weeks to months calculator.