Months to Years Converter
Convert months to years — twelve months to the year. Results update as you type; exact factors shown.
One month (average, 30.4369 days) is 0.0833 year (365.2425 days) — see the exact factor, not a rounded rule of thumb.
How the months to years converter works
Time converts through the second. Minutes, hours, days and weeks are exact multiples. A month is taken as the Gregorian average (30.436875 days) and a year as the Gregorian average (365.2425 days = 31,556,952 s); calendar months and leap years vary from these averages.
The UK is metric for most trade and science but keeps miles, pints, stone and mpg (with the imperial gallon) in daily life.
Common time conversions
| From | To | Units |
|---|---|---|
| 1 mo | 0.0833 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 3 mo | 0.25 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 6 mo | 0.5 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 9 mo | 0.75 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 12 mo | 1 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 18 mo | 1.5 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 24 mo | 2 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 30 mo | 2.5 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 36 mo | 3 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 48 mo | 4 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 60 mo | 5 yr | month (average, 30.4369 days) to year (365.2425 days) |
| 120 mo | 10 yr | month (average, 30.4369 days) to year (365.2425 days) |
Units in this converter and their exact factors
| Unit | Symbol | One unit in seconds |
|---|---|---|
| millisecond | ms | 0.001 second |
| second | s | 1 second |
| minute | min | 60 second |
| hour | h | 3,600 second |
| day | d | 86,400 second |
| week | wk | 604,800 second |
| month (average, 30.4369 days) | mo | 2,629,746 second |
| year (365.2425 days) | yr | 31,556,952 second |
FAQFrequently asked questions about time conversion
How many months in a year?
Twelve.
What is 18 months in years?
1.5 years.
How many months is a 30-year mortgage?
360.
Why does the converter use an average month?
Because calendar months vary from 28 to 31 days; the average of 30.44 days keeps long spans accurate.
What is 60 months?
Five years — a common car-loan term.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Physical Laboratory (NPL) — United Kingdom's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.