Time and Date Converters
Convert between seconds, minutes, hours, days, weeks, months and years instantly.
How many seconds are there in a day? How many weeks in a year? How long is 10,000 hours in years? Time conversions come up in programming, project management, fitness tracking and everyday planning. There are 86,400 seconds in a day, 604,800 seconds in a week, and approximately 31,557,600 seconds in a year (using 365.25 days). Months use a 30.4375-day average and years use 365.25 days to account for leap years. All 42 unit pairs from seconds to years are covered below.
Frequently asked questions
There are 86,400 seconds in a day - calculated as 24 hours × 60 minutes × 60 seconds. This is a fundamental constant in computing, astronomy and physics. A week has 604,800 seconds and a year has approximately 31,557,600 seconds.
10,000 hours equals approximately 1.14 years (10,000 ÷ 8766 hours per year). Malcolm Gladwell's '10,000 hour rule' suggests this is roughly how long it takes to master a skill - about 3 hours a day for 9 years, or full-time work for about 5 years.
There are approximately 52.18 weeks in a year (365.25 ÷ 7). Most years have 52 weeks and 1 day, with leap years having 52 weeks and 2 days. For practical purposes, budgets and planning often use exactly 52 weeks.
90 minutes equals 1.5 hours (90 ÷ 60 = 1.5). In decimal form this is 1.5 hours or 1 hour and 30 minutes. Common conversions: 45 min = 0.75 h, 90 min = 1.5 h, 120 min = 2 h, 150 min = 2.5 h.
The average month has approximately 30.4375 days (365.25 ÷ 12). Individual months have 28-31 days: January 31, February 28 (or 29 in leap years), March 31, April 30, May 31, June 30, July 31, August 31, September 30, October 31, November 30, December 31.
Need other converters? Explore our metric converters, science & engineering and digital storage.