Project future dates by adding months or calculate total elapsed months between two calendar dates.
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A months calculator performs calendar projections based on whole or fractional months. It accurately handles varying calendar month lengths and automatically clips invalid dates (such as April 31 or February 30) to the last valid calendar day.
M_{\text{target}} = (M_{\text{start}} + \Delta M) \pmod{12}The year increments by floor((M_start + DeltaM - 1) / 12) while day numbers exceeding the target month’s length clip to that month’s final day.
Scenario: Signing a 6-month apartment lease on January 31.
Start date: January 31.
Add 6 months -> July 31.
Both January and July have 31 days.
Because February has only 28 days (or 29 in a leap year), adding one month to January 31 clips safely to February 28 or 29.
Depending on which half of the year you measure, 6 months contains between 181 and 184 calendar days (average 182.6 days).
6 months is approximately 26.1 weeks (6 × 4.345 weeks).
Yes, entering negative numbers or using our Date Calculator allows backward projections.
Calculate the exact number of full and decimal years between two dates accounting for leap years.
Convert weeks to days, hours, minutes, and approximate months for pregnancy milestones, school semesters, and projects.
Add or subtract days, weeks, months, and years from any date or calculate the exact duration between two dates.
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