1 year = 365.2425 days = (365.2425 days) × (24 hours/day) × (3600 seconds/hour) = 31556952 seconds

One Julian astronomical year, has 365.25 days:

1 year = 365.25 days = (365.25 days) × (24 hours/day) × (3600 seconds/hour) = 31557600 seconds

One calendar common year has 365 days:

1 common year = 365 days = (365 days) × (24 hours/day) × (3600 seconds/hour) = 31536000 seconds

One calendar leap year has 366 days (occures every 4 years):

1 leap year = 366 days = (366 days) × (24 hours/day) × (3600 seconds/hour) = 31622400 seconds