BCBetter Calculators

Months to Days Calculator

Convert months to days using a 30-day average month.

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Enter your values and click Calculate

How It Works

Calendar months are not equal in length — they range from 28 to 31 days depending on the month and whether the year is a leap year. To produce a consistent and accurate conversion, this calculator multiplies the number of months by 30.4375, which is the mean number of days per month derived from dividing 365.25 days per year by 12. The 365.25 figure accounts for the leap year cycle: three years of 365 days followed by one year of 366 days averages to 365.25 days per year. This method is the standard used in financial, scientific, and legal contexts when an exact calendar is not specified. For example, 6 months × 30.4375 = 182.625 days, and 12 months × 30.4375 = 365.25 days.

Examples

6 months
Half a year, such as a six-month lease or trial period.
Result: 6 months ≈ 182.625 days.
12 months
One full year.
Result: 12 months ≈ 365.25 days.
3 months
A standard quarterly period.
Result: 3 months ≈ 91.31 days.

Frequently Asked Questions

Why 30.4375 and not 30?
30.4375 is derived from dividing 365.25 days per year by 12 months. The 365.25 figure accounts for the leap year cycle. Using 30 instead introduces a small but compounding error, especially over multi-year durations.
How many days is 3 months?
3 × 30.4375 = 91.3125 days, usually rounded to 91.31 days. For a rough estimate, 3 months is approximately 91 days.
Is this calculation accurate enough for legal or financial purposes?
For most general-purpose planning it is accurate. However, some legal contracts or financial instruments specify a different day-count convention — such as 30/360 or actual/365 — so always check the terms of the specific agreement.

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