Month (Avg) to Year (Avg) (mo to yr)
Result
0.08333333333 Year (Avg)
Formula
yr = mo × 0.08333333333
1 mo = 0.08333333333 yr, and 1 yr = 12 mo.
The second is the SI base unit, defined by a caesium-133 transition frequency. Minutes, hours, days and weeks are exact multiples. Month and year here are Gregorian averages: a year of 365.2425 days and a month of one twelfth of that (30.436875 days).
Worked examples
- 1 mo × 0.08333333333 = 0.083333333 yr
- 10 mo × 0.08333333333 = 0.83333333 yr
- 100 mo × 0.08333333333 = 8.3333333 yr
Common mistakes
- Calendar months run from 28 to 31 days, so "3 months" from a given date is not 3 × 30.44 days. Use a date calculator for deadlines.
- A 365-day year, a 365.25-day Julian year and the 365.2425-day Gregorian year differ; interest and astronomy calculations specify which one they use.
Month (Avg) to Year (Avg) table
| Month (Avg) (mo) | Year (Avg) (yr) |
|---|---|
| 1 | 0.083333333 |
| 2 | 0.16666667 |
| 5 | 0.41666667 |
| 10 | 0.83333333 |
| 20 | 1.6666667 |
| 50 | 4.1666667 |
| 100 | 8.3333333 |
| 1,000 | 83.333333 |
The units
- Month (Avg) (mo)
- 1 Month (Avg) = 2,629,746 Second.
- Year (Avg) (yr)
- 1 Year (Avg) = 31,556,952 Second.
Sources for these factors
- The International System of Units (SI Brochure), 9th edition — BIPM
- Guide for the Use of the International System of Units (SP 811), Appendix B: conversion factors — NIST
Last reviewed against these sources. An automated check recomputes every factor from its definition on each build. How we check accuracy