Year (365 days) to Month (30 days)
Year (365 days) (yr (365d))
Month (30 days) (mo (30d))
How it is calculated
Each unit is defined via the base unit (second (s)). The value is first converted to the base unit, then to the selected unit.
1 yr (365d) = 31536000 s
1 mo (30d) = 2592000 s
1 yr (365d) × 31536000 = 31536000 s
31536000 s ÷ 2592000 = 12.1666666667 mo (30d)