Months Between Dates Calculator
Last updated: October 15, 2026
Estimate full calendar months, remaining days and total days between two dates.
Full calendar months
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- Remaining days: —
- Total calendar days: —
- Approximate decimal months: —
On this page
Quick summary: Estimate full calendar months, remaining days and total days between two dates.
Read the method, example and limitations
Updated reference sections in this guide are in English.
Guide language: English. Updated October 15, 2026.
What this calculator estimates
Estimate full calendar months, remaining days and total days between two dates.
Inputs and units
Enter Start year, Start month, Start day, End year, End month, End day. Use the units shown. Required fields cannot be blank. Use zero only where that field and the model allow it. Select Calculate after changing the values.
Method and assumptions
Count whole monthly anniversaries from the earlier date, using the last day of the target month when the starting day is unavailable. Count remaining calendar days from the last completed anniversary. Approximate decimal months use total days / 30.436875.
Worked example
January 31 to February 28, 2026 is 1 completed month and 0 remaining days. January 31 to March 1 is 1 month and 1 day. Reversing the two dates gives the same interval.
Limitations
A decimal month is an average-length month, not an exact calendar month. Contract and legal rules may use different anniversary conventions.